idnits 2.17.1
draft-ietf-dime-rfc3588bis-07.txt:
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line 6806.
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== There are 2 instances of lines with non-RFC2606-compliant FQDNs in the
document.
== There are 2 instances of lines with non-RFC6890-compliant IPv4 addresses
in the document. If these are example addresses, they should be changed.
Miscellaneous warnings:
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== The copyright year in the IETF Trust Copyright Line does not match the
current year
== Line 4536 has weird spacing: '...ly with wit...'
== Line 4744 has weird spacing: '...ealtime user...'
== Line 4772 has weird spacing: '... record inter...'
== Line 4782 has weird spacing: '...ealtime user...'
== Line 4790 has weird spacing: '...ealtime user...'
== (1 more instance...)
== Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD',
or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please
use uppercase 'NOT' together with RFC 2119 keywords (if that is what you
mean).
Found 'MUST not' in this paragraph:
The receiver of the Capabilities-Exchange-Request (CER) MUST
determine common applications by computing the intersection of its own
set of supported application identifiers against all of the application
indentifier AVPs (Auth-Application-Id, Acct-Application-Id and
Vendor-Specific-Application-Id) present in the CER. The value of the
Vendor-Id AVP in the Vendor-Specific-Application-Id MUST not be used
during computation. The sender of the Capabilities-Exchange-Answer (CEA)
SHOULD include all of its supported applications as a hint to the
receiver regarding all of its application capabilities.
== Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD',
or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please
use uppercase 'NOT' together with RFC 2119 keywords (if that is what you
mean).
Found 'MUST not' in this paragraph:
The Destination-Realm AVP MUST be present if the message is
proxiable. Request messages that may be forwarded by Diameter agents
(proxies, redirects or relays) MUST also contain an Acct-Application-Id
AVP, an Auth-Application-Id AVP or a Vendor-Specific-Application-Id AVP.
A message that MUST NOT be forwarded by Diameter agents (proxies,
redirects or relays) MUST not include the Destination-Realm in its ABNF.
The value of the Destination-Realm AVP MAY be extracted from the
User-Name AVP, or other application-specific methods.
-- The document seems to lack a disclaimer for pre-RFC5378 work, but may
have content which was first submitted before 10 November 2008. If you
have contacted all the original authors and they are all willing to grant
the BCP78 rights to the IETF Trust, then this is fine, and you can ignore
this comment. If not, you may need to add the pre-RFC5378 disclaimer.
(See the Legal Provisions document at
https://trustee.ietf.org/license-info for more information.)
-- The document date (September 7, 2007) is 6076 days in the past. Is this
intentional?
Checking references for intended status: Proposed Standard
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(See RFCs 3967 and 4897 for information about using normative references
to lower-maturity documents in RFCs)
== Missing Reference: 'PXY' is mentioned on line 4251, but not defined
-- Possible downref: Non-RFC (?) normative reference: ref. 'FLOATPOINT'
-- Possible downref: Non-RFC (?) normative reference: ref. 'IANAADFAM'
-- Possible downref: Non-RFC (?) normative reference: ref. 'RADTYPE'
** Obsolete normative reference: RFC 793 (ref. 'TCP') (Obsoleted by RFC
9293)
** Obsolete normative reference: RFC 4005 (Obsoleted by RFC 7155)
** Obsolete normative reference: RFC 4006 (Obsoleted by RFC 8506)
** Obsolete normative reference: RFC 4234 (Obsoleted by RFC 5234)
** Obsolete normative reference: RFC 3588 (Obsoleted by RFC 6733)
** Obsolete normative reference: RFC 2434 (Obsoleted by RFC 5226)
** Obsolete normative reference: RFC 4306 (Obsoleted by RFC 5996)
** Obsolete normative reference: RFC 4282 (Obsoleted by RFC 7542)
** Obsolete normative reference: RFC 2960 (Obsoleted by RFC 4960)
** Obsolete normative reference: RFC 4346 (Obsoleted by RFC 5246)
-- Obsolete informational reference (is this intentional?): RFC 3576
(Obsoleted by RFC 5176)
-- Obsolete informational reference (is this intentional?): RFC 4330
(Obsoleted by RFC 5905)
Summary: 11 errors (**), 0 flaws (~~), 12 warnings (==), 12 comments
(--).
Run idnits with the --verbose option for more detailed information about
the items above.
--------------------------------------------------------------------------------
2 DIME V. Fajardo, Ed.
3 Internet-Draft Toshiba America Research
4 Intended status: Standards Track J. Arkko
5 Expires: March 10, 2008 Ericsson Research
6 J. Loughney
7 Nokia Research Center
8 September 7, 2007
10 Diameter Base Protocol
11 draft-ietf-dime-rfc3588bis-07.txt
13 Status of this Memo
15 By submitting this Internet-Draft, each author represents that any
16 applicable patent or other IPR claims of which he or she is aware
17 have been or will be disclosed, and any of which he or she becomes
18 aware will be disclosed, in accordance with Section 6 of BCP 79.
20 Internet-Drafts are working documents of the Internet Engineering
21 Task Force (IETF), its areas, and its working groups. Note that
22 other groups may also distribute working documents as Internet-
23 Drafts.
25 Internet-Drafts are draft documents valid for a maximum of six months
26 and may be updated, replaced, or obsoleted by other documents at any
27 time. It is inappropriate to use Internet-Drafts as reference
28 material or to cite them other than as "work in progress."
30 The list of current Internet-Drafts can be accessed at
31 http://www.ietf.org/ietf/1id-abstracts.txt.
33 The list of Internet-Draft Shadow Directories can be accessed at
34 http://www.ietf.org/shadow.html.
36 This Internet-Draft will expire on March 10, 2008.
38 Copyright Notice
40 Copyright (C) The IETF Trust (2007).
42 Abstract
44 The Diameter base protocol is intended to provide an Authentication,
45 Authorization and Accounting (AAA) framework for applications such as
46 network access or IP mobility. Diameter is also intended to work in
47 both local Authentication, Authorization & Accounting and roaming
48 situations. This document specifies the message format, transport,
49 error reporting, accounting and security services to be used by all
50 Diameter applications. The Diameter base application needs to be
51 supported by all Diameter implementations.
53 Table of Contents
55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 7
56 1.1. Diameter Protocol . . . . . . . . . . . . . . . . . . . . 10
57 1.1.1. Description of the Document Set . . . . . . . . . . 11
58 1.1.2. Conventions Used in This Document . . . . . . . . . 12
59 1.2. Approach to Extensibility . . . . . . . . . . . . . . . . 12
60 1.2.1. Defining New AVP Values . . . . . . . . . . . . . . 13
61 1.2.2. Creating New AVPs . . . . . . . . . . . . . . . . . 13
62 1.2.3. Creating New Commands . . . . . . . . . . . . . . . 13
63 1.2.4. Creating New Authentication Applications . . . . . . 13
64 1.2.5. Creating New Accounting Applications . . . . . . . . 14
65 1.2.6. Application Authentication Procedures . . . . . . . 15
66 1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 16
67 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 22
68 2.1. Transport . . . . . . . . . . . . . . . . . . . . . . . . 23
69 2.1.1. SCTP Guidelines . . . . . . . . . . . . . . . . . . 24
70 2.2. Securing Diameter Messages . . . . . . . . . . . . . . . 24
71 2.3. Diameter Application Compliance . . . . . . . . . . . . . 24
72 2.4. Application Identifiers . . . . . . . . . . . . . . . . . 24
73 2.5. Connections vs. Sessions . . . . . . . . . . . . . . . . 25
74 2.6. Peer Table . . . . . . . . . . . . . . . . . . . . . . . 26
75 2.7. Routing Table . . . . . . . . . . . . . . . . . . . . . . 27
76 2.8. Role of Diameter Agents . . . . . . . . . . . . . . . . . 28
77 2.8.1. Relay Agents . . . . . . . . . . . . . . . . . . . . 30
78 2.8.2. Proxy Agents . . . . . . . . . . . . . . . . . . . . 31
79 2.8.3. Redirect Agents . . . . . . . . . . . . . . . . . . 31
80 2.8.4. Translation Agents . . . . . . . . . . . . . . . . . 32
81 2.9. Diameter Path Authorization . . . . . . . . . . . . . . . 33
82 3. Diameter Header . . . . . . . . . . . . . . . . . . . . . . . 35
83 3.1. Command Codes . . . . . . . . . . . . . . . . . . . . . . 38
84 3.2. Command Code ABNF specification . . . . . . . . . . . . . 38
85 3.3. Diameter Command Naming Conventions . . . . . . . . . . . 40
86 4. Diameter AVPs . . . . . . . . . . . . . . . . . . . . . . . . 42
87 4.1. AVP Header . . . . . . . . . . . . . . . . . . . . . . . 42
88 4.1.1. Optional Header Elements . . . . . . . . . . . . . . 44
90 4.2. Basic AVP Data Formats . . . . . . . . . . . . . . . . . 44
91 4.3. Derived AVP Data Formats . . . . . . . . . . . . . . . . 46
92 4.4. Grouped AVP Values . . . . . . . . . . . . . . . . . . . 52
93 4.4.1. Example AVP with a Grouped Data type . . . . . . . . 53
94 4.5. Diameter Base Protocol AVPs . . . . . . . . . . . . . . . 56
95 5. Diameter Peers . . . . . . . . . . . . . . . . . . . . . . . 59
96 5.1. Peer Connections . . . . . . . . . . . . . . . . . . . . 59
97 5.2. Diameter Peer Discovery . . . . . . . . . . . . . . . . . 59
98 5.3. Capabilities Exchange . . . . . . . . . . . . . . . . . . 62
99 5.3.1. Capabilities-Exchange-Request . . . . . . . . . . . 63
100 5.3.2. Capabilities-Exchange-Answer . . . . . . . . . . . . 64
101 5.3.3. Vendor-Id AVP . . . . . . . . . . . . . . . . . . . 64
102 5.3.4. Firmware-Revision AVP . . . . . . . . . . . . . . . 64
103 5.3.5. Host-IP-Address AVP . . . . . . . . . . . . . . . . 65
104 5.3.6. Supported-Vendor-Id AVP . . . . . . . . . . . . . . 65
105 5.3.7. Product-Name AVP . . . . . . . . . . . . . . . . . . 65
106 5.4. Disconnecting Peer connections . . . . . . . . . . . . . 65
107 5.4.1. Disconnect-Peer-Request . . . . . . . . . . . . . . 66
108 5.4.2. Disconnect-Peer-Answer . . . . . . . . . . . . . . . 66
109 5.4.3. Disconnect-Cause AVP . . . . . . . . . . . . . . . . 66
110 5.5. Transport Failure Detection . . . . . . . . . . . . . . . 67
111 5.5.1. Device-Watchdog-Request . . . . . . . . . . . . . . 67
112 5.5.2. Device-Watchdog-Answer . . . . . . . . . . . . . . . 68
113 5.5.3. Transport Failure Algorithm . . . . . . . . . . . . 68
114 5.5.4. Failover and Failback Procedures . . . . . . . . . . 68
115 5.6. Peer State Machine . . . . . . . . . . . . . . . . . . . 69
116 5.6.1. Incoming connections . . . . . . . . . . . . . . . . 71
117 5.6.2. Events . . . . . . . . . . . . . . . . . . . . . . . 72
118 5.6.3. Actions . . . . . . . . . . . . . . . . . . . . . . 73
119 5.6.4. The Election Process . . . . . . . . . . . . . . . . 75
120 5.6.5. Capabilities Update . . . . . . . . . . . . . . . . 75
121 6. Diameter message processing . . . . . . . . . . . . . . . . . 76
122 6.1. Diameter Request Routing Overview . . . . . . . . . . . . 76
123 6.1.1. Originating a Request . . . . . . . . . . . . . . . 77
124 6.1.2. Sending a Request . . . . . . . . . . . . . . . . . 78
125 6.1.3. Receiving Requests . . . . . . . . . . . . . . . . . 78
126 6.1.4. Processing Local Requests . . . . . . . . . . . . . 78
127 6.1.5. Request Forwarding . . . . . . . . . . . . . . . . . 78
128 6.1.6. Request Routing . . . . . . . . . . . . . . . . . . 79
129 6.1.7. Predictive Loop Avoidance . . . . . . . . . . . . . 79
130 6.1.8. Redirecting requests . . . . . . . . . . . . . . . . 79
131 6.1.9. Relaying and Proxying Requests . . . . . . . . . . . 81
132 6.2. Diameter Answer Processing . . . . . . . . . . . . . . . 81
133 6.2.1. Processing received Answers . . . . . . . . . . . . 82
134 6.2.2. Relaying and Proxying Answers . . . . . . . . . . . 82
135 6.3. Origin-Host AVP . . . . . . . . . . . . . . . . . . . . . 83
136 6.4. Origin-Realm AVP . . . . . . . . . . . . . . . . . . . . 83
137 6.5. Destination-Host AVP . . . . . . . . . . . . . . . . . . 83
138 6.6. Destination-Realm AVP . . . . . . . . . . . . . . . . . . 84
139 6.7. Routing AVPs . . . . . . . . . . . . . . . . . . . . . . 84
140 6.7.1. Route-Record AVP . . . . . . . . . . . . . . . . . . 84
141 6.7.2. Proxy-Info AVP . . . . . . . . . . . . . . . . . . . 84
142 6.7.3. Proxy-Host AVP . . . . . . . . . . . . . . . . . . . 84
143 6.7.4. Proxy-State AVP . . . . . . . . . . . . . . . . . . 84
144 6.8. Auth-Application-Id AVP . . . . . . . . . . . . . . . . . 85
145 6.9. Acct-Application-Id AVP . . . . . . . . . . . . . . . . . 85
146 6.10. Inband-Security-Id AVP . . . . . . . . . . . . . . . . . 85
147 6.11. Vendor-Specific-Application-Id AVP . . . . . . . . . . . 85
148 6.12. Redirect-Host AVP . . . . . . . . . . . . . . . . . . . . 86
149 6.13. Redirect-Host-Usage AVP . . . . . . . . . . . . . . . . . 86
150 6.14. Redirect-Max-Cache-Time AVP . . . . . . . . . . . . . . . 88
151 6.15. E2E-Sequence AVP . . . . . . . . . . . . . . . . . . . . 88
152 7. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 89
153 7.1. Result-Code AVP . . . . . . . . . . . . . . . . . . . . . 90
154 7.1.1. Informational . . . . . . . . . . . . . . . . . . . 91
155 7.1.2. Success . . . . . . . . . . . . . . . . . . . . . . 91
156 7.1.3. Protocol Errors . . . . . . . . . . . . . . . . . . 92
157 7.1.4. Transient Failures . . . . . . . . . . . . . . . . . 93
158 7.1.5. Permanent Failures . . . . . . . . . . . . . . . . . 94
159 7.2. Error Bit . . . . . . . . . . . . . . . . . . . . . . . . 97
160 7.3. Error-Message AVP . . . . . . . . . . . . . . . . . . . . 97
161 7.4. Error-Reporting-Host AVP . . . . . . . . . . . . . . . . 97
162 7.5. Failed-AVP AVP . . . . . . . . . . . . . . . . . . . . . 98
163 7.6. Experimental-Result AVP . . . . . . . . . . . . . . . . . 99
164 7.7. Experimental-Result-Code AVP . . . . . . . . . . . . . . 99
165 8. Diameter User Sessions . . . . . . . . . . . . . . . . . . . 100
166 8.1. Authorization Session State Machine . . . . . . . . . . . 101
167 8.2. Accounting Session State Machine . . . . . . . . . . . . 106
168 8.3. Server-Initiated Re-Auth . . . . . . . . . . . . . . . . 111
169 8.3.1. Re-Auth-Request . . . . . . . . . . . . . . . . . . 111
170 8.3.2. Re-Auth-Answer . . . . . . . . . . . . . . . . . . . 112
171 8.4. Session Termination . . . . . . . . . . . . . . . . . . . 113
172 8.4.1. Session-Termination-Request . . . . . . . . . . . . 114
173 8.4.2. Session-Termination-Answer . . . . . . . . . . . . . 114
174 8.5. Aborting a Session . . . . . . . . . . . . . . . . . . . 115
175 8.5.1. Abort-Session-Request . . . . . . . . . . . . . . . 116
176 8.5.2. Abort-Session-Answer . . . . . . . . . . . . . . . . 116
177 8.6. Inferring Session Termination from Origin-State-Id . . . 117
178 8.7. Auth-Request-Type AVP . . . . . . . . . . . . . . . . . . 118
179 8.8. Session-Id AVP . . . . . . . . . . . . . . . . . . . . . 118
180 8.9. Authorization-Lifetime AVP . . . . . . . . . . . . . . . 119
181 8.10. Auth-Grace-Period AVP . . . . . . . . . . . . . . . . . . 120
182 8.11. Auth-Session-State AVP . . . . . . . . . . . . . . . . . 120
183 8.12. Re-Auth-Request-Type AVP . . . . . . . . . . . . . . . . 121
184 8.13. Session-Timeout AVP . . . . . . . . . . . . . . . . . . . 121
185 8.14. User-Name AVP . . . . . . . . . . . . . . . . . . . . . . 122
186 8.15. Termination-Cause AVP . . . . . . . . . . . . . . . . . . 122
187 8.16. Origin-State-Id AVP . . . . . . . . . . . . . . . . . . . 123
188 8.17. Session-Binding AVP . . . . . . . . . . . . . . . . . . . 123
189 8.18. Session-Server-Failover AVP . . . . . . . . . . . . . . . 124
190 8.19. Multi-Round-Time-Out AVP . . . . . . . . . . . . . . . . 125
191 8.20. Class AVP . . . . . . . . . . . . . . . . . . . . . . . . 125
192 8.21. Event-Timestamp AVP . . . . . . . . . . . . . . . . . . . 125
193 9. Accounting . . . . . . . . . . . . . . . . . . . . . . . . . 127
194 9.1. Server Directed Model . . . . . . . . . . . . . . . . . . 127
195 9.2. Protocol Messages . . . . . . . . . . . . . . . . . . . . 128
196 9.3. Accounting Application Extension and Requirements . . . . 128
197 9.4. Fault Resilience . . . . . . . . . . . . . . . . . . . . 129
198 9.5. Accounting Records . . . . . . . . . . . . . . . . . . . 130
199 9.6. Correlation of Accounting Records . . . . . . . . . . . . 130
200 9.7. Accounting Command-Codes . . . . . . . . . . . . . . . . 131
201 9.7.1. Accounting-Request . . . . . . . . . . . . . . . . . 131
202 9.7.2. Accounting-Answer . . . . . . . . . . . . . . . . . 132
203 9.8. Accounting AVPs . . . . . . . . . . . . . . . . . . . . . 133
204 9.8.1. Accounting-Record-Type AVP . . . . . . . . . . . . . 133
205 9.8.2. Acct-Interim-Interval . . . . . . . . . . . . . . . 134
206 9.8.3. Accounting-Record-Number AVP . . . . . . . . . . . . 135
207 9.8.4. Acct-Session-Id AVP . . . . . . . . . . . . . . . . 135
208 9.8.5. Acct-Multi-Session-Id AVP . . . . . . . . . . . . . 135
209 9.8.6. Accounting-Sub-Session-Id AVP . . . . . . . . . . . 135
210 9.8.7. Accounting-Realtime-Required AVP . . . . . . . . . . 136
211 10. AVP Occurrence Table . . . . . . . . . . . . . . . . . . . . 137
212 10.1. Base Protocol Command AVP Table . . . . . . . . . . . . . 137
213 10.2. Accounting AVP Table . . . . . . . . . . . . . . . . . . 138
214 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 140
215 11.1. AVP Header . . . . . . . . . . . . . . . . . . . . . . . 140
216 11.1.1. AVP Codes . . . . . . . . . . . . . . . . . . . . . 140
217 11.1.2. AVP Flags . . . . . . . . . . . . . . . . . . . . . 141
218 11.2. Diameter Header . . . . . . . . . . . . . . . . . . . . . 141
219 11.2.1. Command Codes . . . . . . . . . . . . . . . . . . . 141
220 11.2.2. Command Flags . . . . . . . . . . . . . . . . . . . 142
221 11.3. Application Identifiers . . . . . . . . . . . . . . . . . 142
222 11.4. AVP Values . . . . . . . . . . . . . . . . . . . . . . . 143
223 11.4.1. Result-Code AVP Values . . . . . . . . . . . . . . . 143
224 11.4.2. Accounting-Record-Type AVP Values . . . . . . . . . 143
225 11.4.3. Termination-Cause AVP Values . . . . . . . . . . . . 143
226 11.4.4. Redirect-Host-Usage AVP Values . . . . . . . . . . . 143
227 11.4.5. Session-Server-Failover AVP Values . . . . . . . . . 143
228 11.4.6. Session-Binding AVP Values . . . . . . . . . . . . . 143
229 11.4.7. Disconnect-Cause AVP Values . . . . . . . . . . . . 144
230 11.4.8. Auth-Request-Type AVP Values . . . . . . . . . . . . 144
231 11.4.9. Auth-Session-State AVP Values . . . . . . . . . . . 144
232 11.4.10. Re-Auth-Request-Type AVP Values . . . . . . . . . . 144
233 11.4.11. Accounting-Realtime-Required AVP Values . . . . . . 144
234 11.4.12. Inband-Security-Id AVP (code 299) . . . . . . . . . 144
235 11.5. Diameter TCP/SCTP Port Numbers . . . . . . . . . . . . . 144
236 11.6. NAPTR Service Fields . . . . . . . . . . . . . . . . . . 144
237 12. Diameter protocol related configurable parameters . . . . . . 146
238 13. Security Considerations . . . . . . . . . . . . . . . . . . . 147
239 13.1. TLS Usage . . . . . . . . . . . . . . . . . . . . . . . . 147
240 13.2. Peer-to-Peer Considerations . . . . . . . . . . . . . . . 148
241 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 149
242 14.1. Normative References . . . . . . . . . . . . . . . . . . 149
243 14.2. Informational References . . . . . . . . . . . . . . . . 151
244 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 153
245 Appendix B. NAPTR Example . . . . . . . . . . . . . . . . . . . 154
246 Appendix C. Duplicate Detection . . . . . . . . . . . . . . . . 155
247 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 157
248 Intellectual Property and Copyright Statements . . . . . . . . . 158
250 1. Introduction
252 Authentication, Authorization and Accounting (AAA) protocols such as
253 TACACS [RFC1492] and RADIUS [RFC2865] were initially deployed to
254 provide dial-up PPP [RFC1661] and terminal server access. Over time,
255 with the growth of the Internet and the introduction of new access
256 technologies, including wireless, DSL, Mobile IP and Ethernet,
257 routers and network access servers (NAS) have increased in complexity
258 and density, putting new demands on AAA protocols.
260 Network access requirements for AAA protocols are summarized in
261 [RFC2989]. These include:
263 Failover
265 [RFC2865] does not define failover mechanisms, and as a result,
266 failover behavior differs between implementations. In order to
267 provide well defined failover behavior, Diameter supports
268 application-layer acknowledgements, and defines failover
269 algorithms and the associated state machine. This is described in
270 Section 5.5 and [RFC3539].
272 Transmission-level security
274 [RFC2865] defines an application-layer authentication and
275 integrity scheme that is required only for use with Response
276 packets. While [RFC2869] defines an additional authentication and
277 integrity mechanism, use is only required during Extensible
278 Authentication Protocol (EAP) sessions. While attribute-hiding is
279 supported, [RFC2865] does not provide support for per-packet
280 confidentiality. In accounting, [RFC2866] assumes that replay
281 protection is provided by the backend billing server, rather than
282 within the protocol itself.
284 While [RFC3162] defines the use of IPsec with RADIUS, support for
285 IPsec is not required. Since within [RFC4306] authentication
286 occurs only within Phase 1 prior to the establishment of IPsec SAs
287 in Phase 2, it is typically not possible to define separate trust
288 or authorization schemes for each application. This limits the
289 usefulness of IPsec in inter-domain AAA applications (such as
290 roaming) where it may be desirable to define a distinct
291 certificate hierarchy for use in a AAA deployment. In order to
292 provide universal support for transmission-level security, and
293 enable both intra- and inter-domain AAA deployments, Diameter also
294 provides support for TLS. Security is discussed in Section 13.
296 Reliable transport
298 RADIUS runs over UDP, and does not define retransmission behavior;
299 as a result, reliability varies between implementations. As
300 described in [RFC2975], this is a major issue in accounting, where
301 packet loss may translate directly into revenue loss. In order to
302 provide well defined transport behavior, Diameter runs over
303 reliable transport mechanisms (TCP, SCTP) as defined in [RFC3539].
305 Agent support
307 [RFC2865] does not provide for explicit support for agents,
308 including Proxies, Redirects and Relays. Since the expected
309 behavior is not defined, it varies between implementations.
310 Diameter defines agent behavior explicitly; this is described in
311 Section 2.8.
313 Server-initiated messages
315 While RADIUS server-initiated messages are defined in [RFC3576],
316 support is optional. This makes it difficult to implement
317 features such as unsolicited disconnect or reauthentication/
318 reauthorization on demand across a heterogeneous deployment.
319 Support for server-initiated messages is mandatory in Diameter,
320 and is described in Section 8.
322 Auditability
324 RADIUS does not define data-object security mechanisms, and as a
325 result, untrusted proxies may modify attributes or even packet
326 headers without being detected. Combined with lack of support for
327 capabilities negotiation, this makes it very difficult to
328 determine what occurred in the event of a dispute.
330 Transition support
332 While Diameter does not share a common protocol data unit (PDU)
333 with RADIUS, considerable effort has been expended in enabling
334 backward compatibility with RADIUS, so that the two protocols may
335 be deployed in the same network. Initially, it is expected that
336 Diameter will be deployed within new network devices, as well as
337 within gateways enabling communication between legacy RADIUS
338 devices and Diameter agents. This capability, described in
340 [RFC4005], enables Diameter support to be added to legacy
341 networks, by addition of a gateway or server speaking both RADIUS
342 and Diameter.
344 In addition to addressing the above requirements, Diameter also
345 provides support for the following:
347 Capability negotiation
349 RADIUS does not support error messages, capability negotiation, or
350 a mandatory/non-mandatory flag for attributes. Since RADIUS
351 clients and servers are not aware of each other's capabilities,
352 they may not be able to successfully negotiate a mutually
353 acceptable service, or in some cases, even be aware of what
354 service has been implemented. Diameter includes support for error
355 handling (Section 7), capability negotiation (Section 5.3), and
356 mandatory/non-mandatory attribute-value pairs (AVPs) (Section
357 4.1).
359 Peer discovery and configuration
361 RADIUS implementations typically require that the name or address
362 of servers or clients be manually configured, along with the
363 corresponding shared secrets. This results in a large
364 administrative burden, and creates the temptation to reuse the
365 RADIUS shared secret, which can result in major security
366 vulnerabilities if the Request Authenticator is not globally and
367 temporally unique as required in [RFC2865]. Through DNS, Diameter
368 enables dynamic discovery of peers. Derivation of dynamic session
369 keys is enabled via transmission-level security.
371 Roaming support
373 The ROAMOPS WG provided a survey of roaming implementations
374 [RFC2194], detailed roaming requirements [RFC2477], defined the
375 Network Access Identifier (NAI)[RFC4282], and documented existing
376 implementations (and imitations) of RADIUS-based roaming
377 [RFC2607]. In order to improve scalability, [RFC2607] introduced
378 the concept of proxy chaining via an intermediate server,
379 facilitating roaming between providers. However, since RADIUS
380 does not provide explicit support for proxies, and lacks
381 auditability and transmission-level security features, RADIUS-
382 based roaming is vulnerable to attack from external parties as
383 well as susceptible to fraud perpetrated by the roaming partners
384 themselves. As a result, it is not suitable for wide-scale
385 deployment on the Internet [RFC2607]. By providing explicit
386 support for inter-domain roaming and message routing (Sections 2.7
387 and 6), and transmission-layer security (Section 13) features,
388 Diameter addresses these limitations and provides for secure and
389 scalable roaming.
391 In the decade since AAA protocols were first introduced, the
392 capabilities of Network Access Server (NAS) devices have increased
393 substantially. As a result, while Diameter is a considerably more
394 sophisticated protocol than RADIUS, it remains feasible to implement
395 within embedded devices, given improvements in processor speeds and
396 the widespread availability of embedded TLS implementations.
398 1.1. Diameter Protocol
400 The Diameter base protocol provides the following facilities:
402 o Delivery of AVPs (attribute value pairs)
404 o Capabilities negotiation
406 o Error notification
408 o Extensibility, through addition of new commands and AVPs (required
409 in [RFC2989]).
411 o Basic services necessary for applications, such as handling of
412 user sessions or accounting
414 All data delivered by the protocol is in the form of an AVP. Some of
415 these AVP values are used by the Diameter protocol itself, while
416 others deliver data associated with particular applications that
417 employ Diameter. AVPs may be added arbitrarily to Diameter messages,
418 so long as the requirements of a message's ABNF are met and the ABNF
419 allows for it. AVPs are used by the base Diameter protocol to
420 support the following required features:
422 o Transporting of user authentication information, for the purposes
423 of enabling the Diameter server to authenticate the user.
425 o Transporting of service specific authorization information,
426 between client and servers, allowing the peers to decide whether a
427 user's access request should be granted.
429 o Exchanging resource usage information, which MAY be used for
430 accounting purposes, capacity planning, etc.
432 o Relaying, proxying and redirecting of Diameter messages through a
433 server hierarchy.
435 The Diameter base protocol provides the minimum requirements needed
436 for a AAA protocol, as required by [RFC2989]. The base protocol may
437 be used by itself for accounting purposes only, or it may be used
438 with a Diameter application, such as Mobile IPv4 [RFC4004], or
439 network access [RFC4005]. It is also possible for the base protocol
440 to be extended for use in new applications, via the addition of new
441 commands or AVPs. At this time the focus of Diameter is network
442 access and accounting applications. A truly generic AAA protocol
443 used by many applications might provide functionality not provided by
444 Diameter. Therefore, it is imperative that the designers of new
445 applications understand their requirements before using Diameter.
446 See Section 2.4 for more information on Diameter applications.
448 Any node can initiate a request. In that sense, Diameter is a peer-
449 to-peer protocol. In this document, a Diameter Client is a device at
450 the edge of the network that performs access control, such as a
451 Network Access Server (NAS) or a Foreign Agent (FA). A Diameter
452 client generates Diameter messages to request authentication,
453 authorization, and accounting services for the user. A Diameter
454 agent is a node that does not authenticate and/or authorize messages
455 locally; agents include proxies, redirects and relay agents. A
456 Diameter server performs authentication and/or authorization of the
457 user. A Diameter node MAY act as an agent for certain requests while
458 acting as a server for others.
460 The Diameter protocol also supports server-initiated messages, such
461 as a request to abort service to a particular user.
463 1.1.1. Description of the Document Set
465 Currently, the Diameter specification consists of a base
466 specification (this document), Transport Profile [RFC3539] and
467 applications: Mobile IPv4 [RFC4004], NASREQ [RFC4005], Credit Control
468 [RFC4006], EAP [RFC4072] and SIP [RFC4740].
470 The Transport Profile document [RFC3539] discusses transport layer
471 issues that arise with AAA protocols and recommendations on how to
472 overcome these issues. This document also defines the Diameter
473 failover algorithm and state machine.
475 The Mobile IPv4 [RFC4004] application defines a Diameter application
476 that allows a Diameter server to perform AAA functions for Mobile
477 IPv4 services to a mobile node.
479 The NASREQ [RFC4005] application defines a Diameter Application that
480 allows a Diameter server to be used in a PPP/SLIP Dial-Up and
481 Terminal Server Access environment. Consideration was given for
482 servers that need to perform protocol conversion between Diameter and
483 RADIUS.
485 The Credit Control [RFC4006] application defines a Diameter
486 Application that can be used to implement real-time credit-control
487 for a variety of end user services such as network access, SIP
488 services, messaging services, and download services. It provides a
489 general solution to real-time cost and credit-control.
491 The EAP [RFC4072] application defines a Diameter Application that can
492 be used to carry EAP packets between the Network Access Server (NAS)
493 working as an EAP authenticator and a back-end authentication server.
494 The Diameter EAP application is based on NASREQ and intended for a
495 similar environment.
497 The SIP [RFC4740] application defines a Diameter Application that
498 allows a Diameter client to request authentication and authorization
499 information to a Diameter server for SIP-based IP multimedia services
500 (see SIP [RFC3261]).
502 In summary, this document defines the base protocol specification for
503 AAA, which includes support for accounting. The applications
504 documents describe applications that use this base specification for
505 Authentication, Authorization and Accounting.
507 1.1.2. Conventions Used in This Document
509 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
510 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
511 document are to be interpreted as described in [RFC2119].
513 1.2. Approach to Extensibility
515 The Diameter protocol is designed to be extensible, using several
516 mechanisms, including:
518 o Defining new AVP values
520 o Creating new AVPs
522 o Creating new commands
524 o Creating new authentication/authorization applications
526 o Creating new accounting applications
527 o Application authentication procedures
529 Reuse of existing AVP values, AVPs, commands and Diameter
530 applications are strongly recommended. Reuse simplifies
531 standardization and implementation and avoids potential
532 interoperability issues.
534 1.2.1. Defining New AVP Values
536 New applications should attempt to reuse AVPs defined in existing
537 applications when possible, as opposed to creating new AVPs. For
538 AVPs of type Enumerated, an application may require a new value to
539 communicate some service-specific information.
541 In order to allocate a new AVP value for a standards track AVP, a
542 request MUST be sent to IANA [RFC2434], along with an explanation of
543 the new AVP value. IANA considerations for AVP values are discussed
544 in Section 11.4.
546 1.2.2. Creating New AVPs
548 When no existing AVP can be reused, a new AVP should be created. The
549 new AVP being defined MUST use one of the data types listed in
550 Section 4.2 or 4.3. If an appropriate derived data type is already
551 defined, it MAY be used instead of the base data type.
553 In the event that a logical grouping of AVPs is necessary, and
554 multiple "groups" are possible in a given command, it is recommended
555 that a Grouped AVP be used (see Section 4.4).
557 In order to create a new standards track AVP, a request MUST be sent
558 to IANA with a reference to the specification that defines the AVP.
559 IANA considerations for AVPs are discussed in Section 11.1.1.
561 1.2.3. Creating New Commands
563 A new command should only be created when no suitable command can be
564 reused from an existing application. A new command MUST result in
565 the defintion of a new application. In order to create a new
566 command, a request MUST be sent to IANA. The IANA considerations for
567 commands are discussed in Section 11.2.1.
569 1.2.4. Creating New Authentication Applications
571 Every Diameter application specification MUST have an IANA assigned
572 Application Identifier (see Section 2.4 and Section 11.3).
574 Should a new Diameter usage scenario find itself unable to fit within
575 an existing application without requiring major changes to the
576 specification, it may be desirable to create a new Diameter
577 application. Major changes to an application include:
579 o Adding new AVPs to the command, which have the "M" bit set.
581 o Requiring a command that has a different number of round trips to
582 satisfy a request (e.g., application foo has a command that
583 requires one round trip, but new application bar has a command
584 that requires two round trips to complete).
586 o Adding support for an authentication method requiring definition
587 of new AVPs for use with the application. Since a new EAP
588 authentication method can be supported within Diameter without
589 requiring new AVPs, addition of EAP methods does not require the
590 creation of a new authentication application.
592 Creation of a new application should be viewed as a last resort. An
593 implementation MAY add arbitrary non-mandatory AVPs to any command
594 defined in an application, including vendor-specific AVPs without
595 needing to define a new application. Please refer to Section 11.1.1
596 for details.
598 In order to justify allocation of a new application identifier,
599 Diameter applications MUST define one Command Code, add new mandatory
600 AVPs to the ABNF or significantly change the state machine or
601 processing rules of an existing application.
603 The expected AVPs MUST be defined in an ABNF [RFC4234] grammar (see
604 Section 3.2). If the Diameter application has accounting
605 requirements, it MUST also specify the AVPs that are to be present in
606 the Diameter Accounting messages (see Section 9.3). However, just
607 because a new authentication application id is required, does not
608 imply that a new accounting application id is required.
610 When possible, a new Diameter application SHOULD reuse existing
611 Diameter AVPs, in order to avoid defining multiple AVPs that carry
612 similar information.
614 1.2.5. Creating New Accounting Applications
616 There are services that only require Diameter accounting. Such
617 services need to define the AVPs carried in the Accounting-Request
618 (ACR)/ Accounting-Answer (ACA) messages, but do not need to define
619 new command codes. An implementation MAY add arbitrary non-mandatory
620 AVPs (AVPs with the "M" bit not set) to any command defined in an
621 application, including vendor-specific AVPs, without needing to
622 define a new accounting application. Please refer to Section 11.1.1
623 for details.
625 Application Identifiers are still required for Diameter capability
626 exchange. Every Diameter accounting application specification MUST
627 have an IANA assigned Application Identifier (see Section 2.4) or a
628 vendor specific Application Identifier.
630 Every Diameter implementation MUST support accounting. Basic
631 accounting support is sufficient to handle any application that uses
632 the ACR/ACA commands defined in this document, as long as no new
633 mandatory AVPs are added. A mandatory AVP is defined as one which
634 has the "M" bit set when sent within an accounting command,
635 regardless of whether it is required or optional within the ABNF for
636 the accounting application.
638 The creation of a new accounting application should be viewed as a
639 last resort and MUST NOT be used unless a new command or additional
640 mechanisms (e.g., application defined state machine) is defined
641 within the application, or new mandatory AVPs are added to the ABNF.
643 Within an accounting command, setting the "M" bit implies that a
644 backend server (e.g., billing server) or the accounting server itself
645 MUST understand the AVP in order to compute a correct bill. If the
646 AVP is not relevant to the billing process, when the AVP is included
647 within an accounting command, it MUST NOT have the "M" bit set, even
648 if the "M" bit is set when the same AVP is used within other Diameter
649 commands (i.e., authentication/authorization commands).
651 A DIAMETER base accounting implementation MUST be configurable to
652 advertise supported accounting applications in order to prevent the
653 accounting server from accepting accounting requests for unbillable
654 services. The combination of the home domain and the accounting
655 application Id can be used in order to route the request to the
656 appropriate accounting server.
658 When possible, a new Diameter accounting application SHOULD attempt
659 to reuse existing AVPs, in order to avoid defining multiple AVPs that
660 carry similar information.
662 If the base accounting is used without any mandatory AVPs, new
663 commands or additional mechanisms (e.g., application defined state
664 machine), then the base protocol defined standard accounting
665 application Id (Section 2.4) MUST be used in ACR/ACA commands.
667 1.2.6. Application Authentication Procedures
669 When possible, applications SHOULD be designed such that new
670 authentication methods MAY be added without requiring changes to the
671 application. This MAY require that new AVP values be assigned to
672 represent the new authentication transform, or any other scheme that
673 produces similar results. When possible, authentication frameworks,
674 such as Extensible Authentication Protocol [RFC3748], SHOULD be used.
676 1.3. Terminology
678 AAA
680 Authentication, Authorization and Accounting.
682 Accounting
684 The act of collecting information on resource usage for the
685 purpose of capacity planning, auditing, billing or cost
686 allocation.
688 Accounting Record
690 An accounting record represents a summary of the resource
691 consumption of a user over the entire session. Accounting servers
692 creating the accounting record may do so by processing interim
693 accounting events or accounting events from several devices
694 serving the same user.
696 Authentication
698 The act of verifying the identity of an entity (subject).
700 Authorization
702 The act of determining whether a requesting entity (subject) will
703 be allowed access to a resource (object).
705 AVP
707 The Diameter protocol consists of a header followed by one or more
708 Attribute-Value-Pairs (AVPs). An AVP includes a header and is
709 used to encapsulate protocol-specific data (e.g., routing
710 information) as well as authentication, authorization or
711 accounting information.
713 Broker
715 A broker is a business term commonly used in AAA infrastructures.
716 A broker is either a relay, proxy or redirect agent, and MAY be
717 operated by roaming consortiums. Depending on the business model,
718 a broker may either choose to deploy relay agents or proxy agents.
720 Diameter Agent
722 A Diameter Agent is a Diameter node that provides either relay,
723 proxy, redirect or translation services.
725 Diameter Client
727 A Diameter Client is a device at the edge of the network that
728 performs access control. An example of a Diameter client is a
729 Network Access Server (NAS) or a Foreign Agent (FA).
731 Diameter Node
733 A Diameter node is a host process that implements the Diameter
734 protocol, and acts either as a Client, Agent or Server.
736 Diameter Peer
738 A Diameter Peer is a Diameter Node to which a given Diameter Node
739 has a direct transport connection.
741 Diameter Server
743 A Diameter Server is one that handles authentication,
744 authorization and accounting requests for a particular realm. By
745 its very nature, a Diameter Server MUST support Diameter
746 applications in addition to the base protocol.
748 Downstream
750 Downstream is used to identify the direction of a particular
751 Diameter message from the home server towards the access device.
753 Home Realm
755 A Home Realm is the administrative domain with which the user
756 maintains an account relationship.
758 Home Server
760 A Diameter Server which serves the Home Realm.
762 Interim accounting
764 An interim accounting message provides a snapshot of usage during
765 a user's session. It is typically implemented in order to provide
766 for partial accounting of a user's session in the case of a device
767 reboot or other network problem prevents the reception of a
768 session summary message or session record.
770 Local Realm
772 A local realm is the administrative domain providing services to a
773 user. An administrative domain MAY act as a local realm for
774 certain users, while being a home realm for others.
776 Multi-session
778 A multi-session represents a logical linking of several sessions.
779 Multi-sessions are tracked by using the Acct-Multi-Session-Id. An
780 example of a multi-session would be a Multi-link PPP bundle. Each
781 leg of the bundle would be a session while the entire bundle would
782 be a multi-session.
784 Network Access Identifier
786 The Network Access Identifier, or NAI [RFC4282], is used in the
787 Diameter protocol to extract a user's identity and realm. The
788 identity is used to identify the user during authentication and/or
789 authorization, while the realm is used for message routing
790 purposes.
792 Proxy Agent or Proxy
794 In addition to forwarding requests and responses, proxies make
795 policy decisions relating to resource usage and provisioning.
796 This is typically accomplished by tracking the state of NAS
797 devices. While proxies typically do not respond to client
798 Requests prior to receiving a Response from the server, they may
799 originate Reject messages in cases where policies are violated.
800 As a result, proxies need to understand the semantics of the
801 messages passing through them, and may not support all Diameter
802 applications.
804 Realm
806 The string in the NAI that immediately follows the '@' character.
807 NAI realm names are required to be unique, and are piggybacked on
808 the administration of the DNS namespace. Diameter makes use of
809 the realm, also loosely referred to as domain, to determine
810 whether messages can be satisfied locally, or whether they must be
811 routed or redirected. In RADIUS, realm names are not necessarily
812 piggybacked on the DNS namespace but may be independent of it.
814 Real-time Accounting
816 Real-time accounting involves the processing of information on
817 resource usage within a defined time window. Time constraints are
818 typically imposed in order to limit financial risk.
820 Relay Agent or Relay
822 Relays forward requests and responses based on routing-related
823 AVPs and routing table entries. Since relays do not make policy
824 decisions, they do not examine or alter non-routing AVPs. As a
825 result, relays never originate messages, do not need to understand
826 the semantics of messages or non-routing AVPs, and are capable of
827 handling any Diameter application or message type. Since relays
828 make decisions based on information in routing AVPs and realm
829 forwarding tables they do not keep state on NAS resource usage or
830 sessions in progress.
832 Redirect Agent
834 Rather than forwarding requests and responses between clients and
835 servers, redirect agents refer clients to servers and allow them
836 to communicate directly. Since redirect agents do not sit in the
837 forwarding path, they do not alter any AVPs transiting between
838 client and server. Redirect agents do not originate messages and
839 are capable of handling any message type, although they may be
840 configured only to redirect messages of certain types, while
841 acting as relay or proxy agents for other types. As with proxy
842 agents, redirect agents do not keep state with respect to sessions
843 or NAS resources.
845 Roaming Relationships
847 Roaming relationships include relationships between companies and
848 ISPs, relationships among peer ISPs within a roaming consortium,
849 and relationships between an ISP and a roaming consortium.
851 Session
853 A session is a related progression of events devoted to a
854 particular activity. Each application SHOULD provide guidelines
855 as to when a session begins and ends. All Diameter packets with
856 the same Session-Identifier are considered to be part of the same
857 session.
859 Session state
861 A stateful agent is one that maintains session state information,
862 by keeping track of all authorized active sessions. Each
863 authorized session is bound to a particular service, and its state
864 is considered active either until it is notified otherwise, or by
865 expiration.
867 Sub-session
869 A sub-session represents a distinct service (e.g., QoS or data
870 characteristics) provided to a given session. These services may
871 happen concurrently (e.g., simultaneous voice and data transfer
872 during the same session) or serially. These changes in sessions
873 are tracked with the Accounting-Sub-Session-Id.
875 Transaction state
877 The Diameter protocol requires that agents maintain transaction
878 state, which is used for failover purposes. Transaction state
879 implies that upon forwarding a request, the Hop-by-Hop identifier
880 is saved; the field is replaced with a locally unique identifier,
881 which is restored to its original value when the corresponding
882 answer is received. The request's state is released upon receipt
883 of the answer. A stateless agent is one that only maintains
884 transaction state.
886 Translation Agent
888 A translation agent is a stateful Diameter node that performs
889 protocol translation between Diameter and another AAA protocol,
890 such as RADIUS.
892 Transport Connection
894 A transport connection is a TCP or SCTP connection existing
895 directly between two Diameter peers, otherwise known as a Peer-
896 to-Peer Connection.
898 Upstream
900 Upstream is used to identify the direction of a particular
901 Diameter message from the access device towards the home server.
903 User
905 The entity requesting or using some resource, in support of which
906 a Diameter client has generated a request.
908 2. Protocol Overview
910 The base Diameter protocol may be used by itself for accounting
911 applications, but for use in authentication and authorization it is
912 always extended for a particular application. Two Diameter
913 applications are defined by companion documents: NASREQ [RFC4005],
914 Mobile IPv4 [RFC4004]. These applications are introduced in this
915 document but specified elsewhere. Additional Diameter applications
916 MAY be defined in the future (see Section 11.3).
918 Diameter Clients MUST support the base protocol, which includes
919 accounting. In addition, they MUST fully support each Diameter
920 application that is needed to implement the client's service, e.g.,
921 NASREQ and/or Mobile IPv4. A Diameter Client that does not support
922 both NASREQ and Mobile IPv4, MUST be referred to as "Diameter X
923 Client" where X is the application which it supports, and not a
924 "Diameter Client".
926 Diameter Servers MUST support the base protocol, which includes
927 accounting. In addition, they MUST fully support each Diameter
928 application that is needed to implement the intended service, e.g.,
929 NASREQ and/or Mobile IPv4. A Diameter Server that does not support
930 both NASREQ and Mobile IPv4, MUST be referred to as "Diameter X
931 Server" where X is the application which it supports, and not a
932 "Diameter Server".
934 Diameter Relays and redirect agents are, by definition, protocol
935 transparent, and MUST transparently support the Diameter base
936 protocol, which includes accounting, and all Diameter applications.
938 Diameter proxies MUST support the base protocol, which includes
939 accounting. In addition, they MUST fully support each Diameter
940 application that is needed to implement proxied services, e.g.,
941 NASREQ and/or Mobile IPv4. A Diameter proxy which does not support
942 also both NASREQ and Mobile IPv4, MUST be referred to as "Diameter X
943 Proxy" where X is the application which it supports, and not a
944 "Diameter Proxy".
946 The base Diameter protocol concerns itself with capabilities
947 negotiation, how messages are sent and how peers may eventually be
948 abandoned. The base protocol also defines certain rules that apply
949 to all exchanges of messages between Diameter nodes.
951 Communication between Diameter peers begins with one peer sending a
952 message to another Diameter peer. The set of AVPs included in the
953 message is determined by a particular Diameter application. One AVP
954 that is included to reference a user's session is the Session-Id.
956 The initial request for authentication and/or authorization of a user
957 would include the Session-Id. The Session-Id is then used in all
958 subsequent messages to identify the user's session (see Section 8 for
959 more information). The communicating party may accept the request,
960 or reject it by returning an answer message with the Result-Code AVP
961 set to indicate an error occurred. The specific behavior of the
962 Diameter server or client receiving a request depends on the Diameter
963 application employed.
965 Session state (associated with a Session-Id) MUST be freed upon
966 receipt of the Session-Termination-Request, Session-Termination-
967 Answer, expiration of authorized service time in the Session-Timeout
968 AVP, and according to rules established in a particular Diameter
969 application.
971 2.1. Transport
973 Transport profile is defined in [RFC3539].
975 The base Diameter protocol is run on port 3868 of both TCP [TCP] and
976 SCTP [RFC2960] transport protocols.
978 Diameter clients MUST support either TCP or SCTP, while agents and
979 servers MUST support both. Future versions of this specification MAY
980 mandate that clients support SCTP.
982 A Diameter node MAY initiate connections from a source port other
983 than the one that it declares it accepts incoming connections on, and
984 MUST be prepared to receive connections on port 3868. A given
985 Diameter instance of the peer state machine MUST NOT use more than
986 one transport connection to communicate with a given peer, unless
987 multiple instances exist on the peer in which case a separate
988 connection per process is allowed.
990 When no transport connection exists with a peer, an attempt to
991 connect SHOULD be periodically made. This behavior is handled via
992 the Tc timer, whose recommended value is 30 seconds. There are
993 certain exceptions to this rule, such as when a peer has terminated
994 the transport connection stating that it does not wish to
995 communicate.
997 When connecting to a peer and either zero or more transports are
998 specified, SCTP SHOULD be tried first, followed by TCP. See Section
999 5.2 for more information on peer discovery.
1001 Diameter implementations SHOULD be able to interpret ICMP protocol
1002 port unreachable messages as explicit indications that the server is
1003 not reachable, subject to security policy on trusting such messages.
1005 Diameter implementations SHOULD also be able to interpret a reset
1006 from the transport and timed-out connection attempts. If Diameter
1007 receives data up from TCP that cannot be parsed or identified as a
1008 Diameter error made by the peer, the stream is compromised and cannot
1009 be recovered. The transport connection MUST be closed using a RESET
1010 call (send a TCP RST bit) or an SCTP ABORT message (graceful closure
1011 is compromised).
1013 2.1.1. SCTP Guidelines
1015 The following are guidelines for Diameter implementations that
1016 support SCTP:
1018 1. For interoperability: All Diameter nodes MUST be prepared to
1019 receive Diameter messages on any SCTP stream in the association.
1021 2. To prevent blocking: All Diameter nodes SHOULD utilize all SCTP
1022 streams available to the association to prevent head-of-the-line
1023 blocking.
1025 2.2. Securing Diameter Messages
1027 Diameter clients, such as Network Access Servers (NASes) and Mobility
1028 Agents MAY support TLS [RFC4346]. Diameter servers MUST support TLS.
1029 IPSec [RFC4301] can be deployed between Diameter peers as an
1030 additional security measure independent of the Diameter protocol.
1031 The Diameter protocol SHOULD NOT be used without any security
1032 mechanism.
1034 2.3. Diameter Application Compliance
1036 Application Identifiers are advertised during the capabilities
1037 exchange phase (see Section 5.3). For a given application,
1038 advertising support of an application implies that the sender
1039 supports all command codes, and the AVPs specified in the associated
1040 ABNFs, described in the specification.
1042 An implementation MAY add arbitrary non-mandatory AVPs to any command
1043 defined in an application, including vendor-specific AVPs. Please
1044 refer to Section 11.1.1 for details.
1046 2.4. Application Identifiers
1048 Each Diameter application MUST have an IANA assigned Application
1049 Identifier (see Section 11.3). The base protocol does not require an
1050 Application Identifier since its support is mandatory. During the
1051 capabilities exchange, Diameter nodes inform their peers of locally
1052 supported applications. Furthermore, all Diameter messages contain
1053 an Application Identifier, which is used in the message forwarding
1054 process.
1056 The following Application Identifier values are defined:
1058 Diameter Common Messages 0
1059 NASREQ 1 [RFC4005]
1060 Mobile-IP 2 [RFC4004]
1061 Diameter Base Accounting 3
1062 Relay 0xffffffff
1064 Relay and redirect agents MUST advertise the Relay Application
1065 Identifier, while all other Diameter nodes MUST advertise locally
1066 supported applications. The receiver of a Capabilities Exchange
1067 message advertising Relay service MUST assume that the sender
1068 supports all current and future applications.
1070 Diameter relay and proxy agents are responsible for finding an
1071 upstream server that supports the application of a particular
1072 message. If none can be found, an error message is returned with the
1073 Result-Code AVP set to DIAMETER_UNABLE_TO_DELIVER.
1075 2.5. Connections vs. Sessions
1077 This section attempts to provide the reader with an understanding of
1078 the difference between connection and session, which are terms used
1079 extensively throughout this document.
1081 A connection is a transport level connection between two peers, used
1082 to send and receive Diameter messages. A session is a logical
1083 concept at the application layer, and is shared between an access
1084 device and a server, and is identified via the Session-Id AVP.
1086 +--------+ +-------+ +--------+
1087 | Client | | Relay | | Server |
1088 +--------+ +-------+ +--------+
1089 <----------> <---------->
1090 peer connection A peer connection B
1092 <----------------------------->
1093 User session x
1095 Figure 1: Diameter connections and sessions
1097 In the example provided in Figure 1, peer connection A is established
1098 between the Client and its local Relay. Peer connection B is
1099 established between the Relay and the Server. User session X spans
1100 from the Client via the Relay to the Server. Each "user" of a
1101 service causes an auth request to be sent, with a unique session
1102 identifier. Once accepted by the server, both the client and the
1103 server are aware of the session.
1105 It is important to note that there is no relationship between a
1106 connection and a session, and that Diameter messages for multiple
1107 sessions are all multiplexed through a single connection. Also note
1108 that Diameter messages pertaining to the session, both application
1109 specific and those that are defined in this document such as ASR/ASA,
1110 RAR/RAA and STR/STA MUST carry the application identifier of the
1111 application. Diameter messages pertaining to peer connection
1112 establishment and maintenance such as CER/CEA, DWR/DWA and DPR/DPA
1113 MUST carry an application id of zero (0).
1115 2.6. Peer Table
1117 The Diameter Peer Table is used in message forwarding, and referenced
1118 by the Routing Table. A Peer Table entry contains the following
1119 fields:
1121 Host identity
1123 Following the conventions described for the DiameterIdentity
1124 derived AVP data format in Section 4.4. This field contains the
1125 contents of the Origin-Host (Section 6.3) AVP found in the CER or
1126 CEA message.
1128 StatusT
1130 This is the state of the peer entry, and MUST match one of the
1131 values listed in Section 5.6.
1133 Static or Dynamic
1135 Specifies whether a peer entry was statically configured, or
1136 dynamically discovered.
1138 Expiration time
1140 Specifies the time at which dynamically discovered peer table
1141 entries are to be either refreshed, or expired.
1143 TLS Enabled
1145 Specifies whether TLS is to be used when communicating with the
1146 peer.
1148 Additional security information, when needed (e.g., keys,
1149 certificates)
1151 2.7. Routing Table
1153 All Realm-Based routing lookups are performed against what is
1154 commonly known as the Routing Table (see Section 12). A Routing
1155 Table Entry contains the following fields:
1157 Realm Name
1159 This is the field that is typically used as a primary key in the
1160 routing table lookups. Note that some implementations perform
1161 their lookups based on longest-match-from-the-right on the realm
1162 rather than requiring an exact match.
1164 Application Identifier
1166 An application is identified by an application id. A route entry
1167 can have a different destination based on the application
1168 identification in the message header. This field MUST be used as
1169 a secondary key field in routing table lookups.
1171 Local Action
1173 The Local Action field is used to identify how a message should be
1174 treated. The following actions are supported:
1176 1. LOCAL - Diameter messages that resolve to a route entry with
1177 the Local Action set to Local can be satisfied locally, and do
1178 not need to be routed to another server.
1180 2. RELAY - All Diameter messages that fall within this category
1181 MUST be routed to a next hop server, without modifying any
1182 non-routing AVPs. See Section 6.1.9 for relaying guidelines
1184 3. PROXY - All Diameter messages that fall within this category
1185 MUST be routed to a next hop server. The local server MAY
1186 apply its local policies to the message by including new AVPs
1187 to the message prior to routing. See Section 6.1.9 for
1188 proxying guidelines.
1190 4. REDIRECT - Diameter messages that fall within this category
1191 MUST have the identity of the home Diameter server(s)
1192 appended, and returned to the sender of the message. See
1193 Section 6.1.9 for redirect guidelines.
1195 Server Identifier
1197 One or more servers the message is to be routed to. These servers
1198 MUST also be present in the Peer table. When the Local Action is
1199 set to RELAY or PROXY, this field contains the identity of the
1200 server(s) the message must be routed to. When the Local Action
1201 field is set to REDIRECT, this field contains the identity of one
1202 or more servers the message should be redirected to.
1204 Static or Dynamic
1206 Specifies whether a route entry was statically configured, or
1207 dynamically discovered.
1209 Expiration time
1211 Specifies the time which a dynamically discovered route table
1212 entry expires.
1214 It is important to note that Diameter agents MUST support at least
1215 one of the LOCAL, RELAY, PROXY or REDIRECT modes of operation.
1216 Agents do not need to support all modes of operation in order to
1217 conform with the protocol specification, but MUST follow the protocol
1218 compliance guidelines in Section 2. Relay agents MUST NOT reorder
1219 AVPs, and proxies MUST NOT reorder AVPs.
1221 The routing table MAY include a default entry that MUST be used for
1222 any requests not matching any of the other entries. The routing
1223 table MAY consist of only such an entry.
1225 When a request is routed, the target server MUST have advertised the
1226 Application Identifier (see Section 2.4) for the given message, or
1227 have advertised itself as a relay or proxy agent. Otherwise, an
1228 error is returned with the Result-Code AVP set to
1229 DIAMETER_UNABLE_TO_DELIVER.
1231 2.8. Role of Diameter Agents
1233 In addition to client and servers, the Diameter protocol introduces
1234 relay, proxy, redirect, and translation agents, each of which is
1235 defined in Section 1.3. These Diameter agents are useful for several
1236 reasons:
1238 o They can distribute administration of systems to a configurable
1239 grouping, including the maintenance of security associations.
1241 o They can be used for concentration of requests from an number of
1242 co-located or distributed NAS equipment sets to a set of like user
1243 groups.
1245 o They can do value-added processing to the requests or responses.
1247 o They can be used for load balancing.
1249 o A complex network will have multiple authentication sources, they
1250 can sort requests and forward towards the correct target.
1252 The Diameter protocol requires that agents maintain transaction
1253 state, which is used for failover purposes. Transaction state
1254 implies that upon forwarding a request, its Hop-by-Hop identifier is
1255 saved; the field is replaced with a locally unique identifier, which
1256 is restored to its original value when the corresponding answer is
1257 received. The request's state is released upon receipt of the
1258 answer. A stateless agent is one that only maintains transaction
1259 state.
1261 The Proxy-Info AVP allows stateless agents to add local state to a
1262 Diameter request, with the guarantee that the same state will be
1263 present in the answer. However, the protocol's failover procedures
1264 require that agents maintain a copy of pending requests.
1266 A stateful agent is one that maintains session state information; by
1267 keeping track of all authorized active sessions. Each authorized
1268 session is bound to a particular service, and its state is considered
1269 active either until it is notified otherwise, or by expiration. Each
1270 authorized session has an expiration, which is communicated by
1271 Diameter servers via the Session-Timeout AVP.
1273 Maintaining session state MAY be useful in certain applications, such
1274 as:
1276 o Protocol translation (e.g., RADIUS <-> Diameter)
1278 o Limiting resources authorized to a particular user
1280 o Per user or transaction auditing
1282 A Diameter agent MAY act in a stateful manner for some requests and
1283 be stateless for others. A Diameter implementation MAY act as one
1284 type of agent for some requests, and as another type of agent for
1285 others.
1287 2.8.1. Relay Agents
1289 Relay Agents are Diameter agents that accept requests and route
1290 messages to other Diameter nodes based on information found in the
1291 messages (e.g., Destination-Realm). This routing decision is
1292 performed using a list of supported realms, and known peers. This is
1293 known as the Routing Table, as is defined further in Section 2.7.
1295 Relays MAY be used to aggregate requests from multiple Network Access
1296 Servers (NASes) within a common geographical area (POP). The use of
1297 Relays is advantageous since it eliminates the need for NASes to be
1298 configured with the necessary security information they would
1299 otherwise require to communicate with Diameter servers in other
1300 realms. Likewise, this reduces the configuration load on Diameter
1301 servers that would otherwise be necessary when NASes are added,
1302 changed or deleted.
1304 Relays modify Diameter messages by inserting and removing routing
1305 information, but do not modify any other portion of a message.
1306 Relays SHOULD NOT maintain session state but MUST maintain
1307 transaction state.
1309 +------+ ---------> +------+ ---------> +------+
1310 | | 1. Request | | 2. Request | |
1311 | NAS | | DRL | | HMS |
1312 | | 4. Answer | | 3. Answer | |
1313 +------+ <--------- +------+ <--------- +------+
1314 example.net example.net example.com
1316 Figure 2: Relaying of Diameter messages
1318 The example provided in Figure 2 depicts a request issued from NAS,
1319 which is an access device, for the user bob@example.com. Prior to
1320 issuing the request, NAS performs a Diameter route lookup, using
1321 "example.com" as the key, and determines that the message is to be
1322 relayed to DRL, which is a Diameter Relay. DRL performs the same
1323 route lookup as NAS, and relays the message to HMS, which is
1324 example.com's Home Diameter Server. HMS identifies that the request
1325 can be locally supported (via the realm), processes the
1326 authentication and/or authorization request, and replies with an
1327 answer, which is routed back to NAS using saved transaction state.
1329 Since Relays do not perform any application level processing, they
1330 provide relaying services for all Diameter applications, and
1331 therefore MUST advertise the Relay Application Identifier.
1333 2.8.2. Proxy Agents
1335 Similarly to relays, proxy agents route Diameter messages using the
1336 Diameter Routing Table. However, they differ since they modify
1337 messages to implement policy enforcement. This requires that proxies
1338 maintain the state of their downstream peers (e.g., access devices)
1339 to enforce resource usage, provide admission control, and
1340 provisioning.
1342 Proxies MAY be used in call control centers or access ISPs that
1343 provide outsourced connections, they can monitor the number and types
1344 of ports in use, and make allocation and admission decisions
1345 according to their configuration.
1347 Proxies that wish to limit resources MUST maintain session state.
1348 All proxies MUST maintain transaction state.
1350 Since enforcing policies requires an understanding of the service
1351 being provided, Proxies MUST only advertise the Diameter applications
1352 they support.
1354 2.8.3. Redirect Agents
1356 Redirect agents are useful in scenarios where the Diameter routing
1357 configuration needs to be centralized. An example is a redirect
1358 agent that provides services to all members of a consortium, but does
1359 not wish to be burdened with relaying all messages between realms.
1360 This scenario is advantageous since it does not require that the
1361 consortium provide routing updates to its members when changes are
1362 made to a member's infrastructure.
1364 Since redirect agents do not relay messages, and only return an
1365 answer with the information necessary for Diameter agents to
1366 communicate directly, they do not modify messages. Since redirect
1367 agents do not receive answer messages, they cannot maintain session
1368 state. Further, since redirect agents never relay requests, they are
1369 not required to maintain transaction state.
1371 The example provided in Figure 3 depicts a request issued from the
1372 access device, NAS, for the user bob@example.com. The message is
1373 forwarded by the NAS to its relay, DRL, which does not have a routing
1374 entry in its Diameter Routing Table for example.com. DRL has a
1375 default route configured to DRD, which is a redirect agent that
1376 returns a redirect notification to DRL, as well as HMS' contact
1377 information. Upon receipt of the redirect notification, DRL
1378 establishes a transport connection with HMS, if one doesn't already
1379 exist, and forwards the request to it.
1381 +------+
1382 | |
1383 | DRD |
1384 | |
1385 +------+
1386 ^ |
1387 2. Request | | 3. Redirection
1388 | | Notification
1389 | v
1390 +------+ ---------> +------+ ---------> +------+
1391 | | 1. Request | | 4. Request | |
1392 | NAS | | DRL | | HMS |
1393 | | 6. Answer | | 5. Answer | |
1394 +------+ <--------- +------+ <--------- +------+
1395 example.net example.net example.com
1397 Figure 3: Redirecting a Diameter Message
1399 Since redirect agents do not perform any application level
1400 processing, they provide relaying services for all Diameter
1401 applications, and therefore MUST advertise the Relay Application
1402 Identifier.
1404 2.8.4. Translation Agents
1406 A translation agent is a device that provides translation between two
1407 protocols (e.g., RADIUS<->Diameter, TACACS+<->Diameter). Translation
1408 agents are likely to be used as aggregation servers to communicate
1409 with a Diameter infrastructure, while allowing for the embedded
1410 systems to be migrated at a slower pace.
1412 Given that the Diameter protocol introduces the concept of long-lived
1413 authorized sessions, translation agents MUST be session stateful and
1414 MUST maintain transaction state.
1416 Translation of messages can only occur if the agent recognizes the
1417 application of a particular request, and therefore translation agents
1418 MUST only advertise their locally supported applications.
1420 +------+ ---------> +------+ ---------> +------+
1421 | | RADIUS Request | | Diameter Request | |
1422 | NAS | | TLA | | HMS |
1423 | | RADIUS Answer | | Diameter Answer | |
1424 +------+ <--------- +------+ <--------- +------+
1425 example.net example.net example.com
1426 Figure 4: Translation of RADIUS to Diameter
1428 2.9. Diameter Path Authorization
1430 As noted in Section 2.2, Diameter provides transmission level
1431 security for each connection using TLS. Therefore, each connection
1432 can be authenticated, replay and integrity protected.
1434 In addition to authenticating each connection, each connection as
1435 well as the entire session MUST also be authorized. Before
1436 initiating a connection, a Diameter Peer MUST check that its peers
1437 are authorized to act in their roles. For example, a Diameter peer
1438 may be authentic, but that does not mean that it is authorized to act
1439 as a Diameter Server advertising a set of Diameter applications.
1441 Prior to bringing up a connection, authorization checks are performed
1442 at each connection along the path. Diameter capabilities negotiation
1443 (CER/CEA) also MUST be carried out, in order to determine what
1444 Diameter applications are supported by each peer. Diameter sessions
1445 MUST be routed only through authorized nodes that have advertised
1446 support for the Diameter application required by the session.
1448 As noted in Section 6.1.9, a relay or proxy agent MUST append a
1449 Route-Record AVP to all requests forwarded. The AVP contains the
1450 identity of the peer the request was received from.
1452 The home Diameter server, prior to authorizing a session, MUST check
1453 the Route-Record AVPs to make sure that the route traversed by the
1454 request is acceptable. For example, administrators within the home
1455 realm may not wish to honor requests that have been routed through an
1456 untrusted realm. By authorizing a request, the home Diameter server
1457 is implicitly indicating its willingness to engage in the business
1458 transaction as specified by the contractual relationship between the
1459 server and the previous hop. A DIAMETER_AUTHORIZATION_REJECTED error
1460 message (see Section 7.1.5) is sent if the route traversed by the
1461 request is unacceptable.
1463 A home realm may also wish to check that each accounting request
1464 message corresponds to a Diameter response authorizing the session.
1465 Accounting requests without corresponding authorization responses
1466 SHOULD be subjected to further scrutiny, as should accounting
1467 requests indicating a difference between the requested and provided
1468 service.
1470 Forwarding of an authorization response is considered evidence of a
1471 willingness to take on financial risk relative to the session. A
1472 local realm may wish to limit this exposure, for example, by
1473 establishing credit limits for intermediate realms and refusing to
1474 accept responses which would violate those limits. By issuing an
1475 accounting request corresponding to the authorization response, the
1476 local realm implicitly indicates its agreement to provide the service
1477 indicated in the authorization response. If the service cannot be
1478 provided by the local realm, then a DIAMETER_UNABLE_TO_COMPLY error
1479 message MUST be sent within the accounting request; a Diameter client
1480 receiving an authorization response for a service that it cannot
1481 perform MUST NOT substitute an alternate service, and then send
1482 accounting requests for the alternate service instead.
1484 3. Diameter Header
1486 A summary of the Diameter header format is shown below. The fields
1487 are transmitted in network byte order.
1489 0 1 2 3
1490 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1491 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1492 | Version | Message Length |
1493 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1494 | command flags | Command-Code |
1495 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1496 | Application-ID |
1497 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1498 | Hop-by-Hop Identifier |
1499 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1500 | End-to-End Identifier |
1501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1502 | AVPs ...
1503 +-+-+-+-+-+-+-+-+-+-+-+-+-
1505 Version
1507 This Version field MUST be set to 1 to indicate Diameter Version
1508 1.
1510 Message Length
1512 The Message Length field is three octets and indicates the length
1513 of the Diameter message including the header fields.
1515 Command Flags
1517 The Command Flags field is eight bits. The following bits are
1518 assigned:
1520 0 1 2 3 4 5 6 7
1521 +-+-+-+-+-+-+-+-+
1522 |R P E T r r r r|
1523 +-+-+-+-+-+-+-+-+
1525 R(equest)
1527 If set, the message is a request. If cleared, the message is
1528 an answer.
1530 P(roxiable)
1532 If set, the message MAY be proxied, relayed or redirected. If
1533 cleared, the message MUST be locally processed.
1535 E(rror)
1537 If set, the message contains a protocol error, and the message
1538 will not conform to the ABNF described for this command.
1539 Messages with the 'E' bit set are commonly referred to as error
1540 messages. This bit MUST NOT be set in request messages. See
1541 Section 7.2.
1543 T(Potentially re-transmitted message)
1545 This flag is set after a link failover procedure, to aid the
1546 removal of duplicate requests. It is set when resending
1547 requests not yet acknowledged, as an indication of a possible
1548 duplicate due to a link failure. This bit MUST be cleared when
1549 sending a request for the first time, otherwise the sender MUST
1550 set this flag. Diameter agents only need to be concerned about
1551 the number of requests they send based on a single received
1552 request; retransmissions by other entities need not be tracked.
1553 Diameter agents that receive a request with the T flag set,
1554 MUST keep the T flag set in the forwarded request. This flag
1555 MUST NOT be set if an error answer message (e.g., a protocol
1556 error) has been received for the earlier message. It can be
1557 set only in cases where no answer has been received from the
1558 server for a request and the request is sent again. This flag
1559 MUST NOT be set in answer messages.
1561 r(eserved)
1563 These flag bits are reserved for future use, and MUST be set to
1564 zero, and ignored by the receiver.
1566 Command-Code
1568 The Command-Code field is three octets, and is used in order to
1569 communicate the command associated with the message. The 24-bit
1570 address space is managed by IANA (see Section 11.2.1).
1572 Command-Code values 16,777,214 and 16,777,215 (hexadecimal values
1573 FFFFFE -FFFFFF) are reserved for experimental use (See Section
1574 11.3).
1576 Application-ID
1578 Application-ID is four octets and is used to identify to which
1579 application the message is applicable for. The application can be
1580 an authentication application, an accounting application or a
1581 vendor specific application. See Section 11.3 for the possible
1582 values that the application-id may use.
1584 The application-id in the header MUST be the same as what is
1585 contained in any relevant application-id AVPs contained in the
1586 message.
1588 Hop-by-Hop Identifier
1590 The Hop-by-Hop Identifier is an unsigned 32-bit integer field (in
1591 network byte order) and aids in matching requests and replies.
1592 The sender MUST ensure that the Hop-by-Hop identifier in a request
1593 is unique on a given connection at any given time, and MAY attempt
1594 to ensure that the number is unique across reboots. The sender of
1595 an Answer message MUST ensure that the Hop-by-Hop Identifier field
1596 contains the same value that was found in the corresponding
1597 request. The Hop-by-Hop identifier is normally a monotonically
1598 increasing number, whose start value was randomly generated. An
1599 answer message that is received with an unknown Hop-by-Hop
1600 Identifier MUST be discarded.
1602 End-to-End Identifier
1604 The End-to-End Identifier is an unsigned 32-bit integer field (in
1605 network byte order) and is used to detect duplicate messages.
1606 Upon reboot implementations MAY set the high order 12 bits to
1607 contain the low order 12 bits of current time, and the low order
1608 20 bits to a random value. Senders of request messages MUST
1609 insert a unique identifier on each message. The identifier MUST
1610 remain locally unique for a period of at least 4 minutes, even
1611 across reboots. The originator of an Answer message MUST ensure
1612 that the End-to-End Identifier field contains the same value that
1613 was found in the corresponding request. The End-to-End Identifier
1614 MUST NOT be modified by Diameter agents of any kind. The
1615 combination of the Origin-Host (see Section 6.3) and this field is
1616 used to detect duplicates. Duplicate requests SHOULD cause the
1617 same answer to be transmitted (modulo the hop-by-hop Identifier
1618 field and any routing AVPs that may be present), and MUST NOT
1619 affect any state that was set when the original request was
1620 processed. Duplicate answer messages that are to be locally
1621 consumed (see Section 6.2) SHOULD be silently discarded.
1623 AVPs
1625 AVPs are a method of encapsulating information relevant to the
1626 Diameter message. See Section 4 for more information on AVPs.
1628 3.1. Command Codes
1630 Each command Request/Answer pair is assigned a command code, and the
1631 sub-type (i.e., request or answer) is identified via the 'R' bit in
1632 the Command Flags field of the Diameter header.
1634 Every Diameter message MUST contain a command code in its header's
1635 Command-Code field, which is used to determine the action that is to
1636 be taken for a particular message. The following Command Codes are
1637 defined in the Diameter base protocol:
1639 Command-Name Abbrev. Code Reference
1640 --------------------------------------------------------
1641 Abort-Session-Request ASR 274 8.5.1
1642 Abort-Session-Answer ASA 274 8.5.2
1643 Accounting-Request ACR 271 9.7.1
1644 Accounting-Answer ACA 271 9.7.2
1645 Capabilities-Exchange- CER 257 5.3.1
1646 Request
1647 Capabilities-Exchange- CEA 257 5.3.2
1648 Answer
1649 Device-Watchdog-Request DWR 280 5.5.1
1650 Device-Watchdog-Answer DWA 280 5.5.2
1651 Disconnect-Peer-Request DPR 282 5.4.1
1652 Disconnect-Peer-Answer DPA 282 5.4.2
1653 Re-Auth-Request RAR 258 8.3.1
1654 Re-Auth-Answer RAA 258 8.3.2
1655 Session-Termination- STR 275 8.4.1
1656 Request
1657 Session-Termination- STA 275 8.4.2
1658 Answer
1660 3.2. Command Code ABNF specification
1662 Every Command Code defined MUST include a corresponding ABNF
1663 specification, which is used to define the AVPs that MUST or MAY be
1664 present. The following format is used in the definition:
1666 command-def = command-name "::=" diameter-message
1668 command-name = diameter-name
1669 diameter-name = ALPHA *(ALPHA / DIGIT / "-")
1671 diameter-message = header [ *fixed] [ *required] [ *optional]
1673 header = "<" "Diameter Header:" command-id
1674 [r-bit] [p-bit] [e-bit] [application-id] ">"
1676 application-id = 1*DIGIT
1678 command-id = 1*DIGIT
1679 ; The Command Code assigned to the command
1681 r-bit = ", REQ"
1682 ; If present, the 'R' bit in the Command
1683 ; Flags is set, indicating that the message
1684 ; is a request, as opposed to an answer.
1686 p-bit = ", PXY"
1687 ; If present, the 'P' bit in the Command
1688 ; Flags is set, indicating that the message
1689 ; is proxiable.
1691 e-bit = ", ERR"
1692 ; If present, the 'E' bit in the Command
1693 ; Flags is set, indicating that the answer
1694 ; message contains a Result-Code AVP in
1695 ; the "protocol error" class.
1697 fixed = [qual] "<" avp-spec ">"
1698 ; Defines the fixed position of an AVP
1700 required = [qual] "{" avp-spec "}"
1701 ; The AVP MUST be present and can appear
1702 ; anywhere in the message.
1704 optional = [qual] "[" avp-name "]"
1705 ; The avp-name in the 'optional' rule cannot
1706 ; evaluate to any AVP Name which is included
1707 ; in a fixed or required rule. The AVP can
1708 ; appear anywhere in the message.
1710 qual = [min] "*" [max]
1711 ; See ABNF conventions, RFC 4234 Section 6.6.
1712 ; The absence of any qualifiers depends on
1713 ; whether it precedes a fixed, required, or
1714 ; optional rule. If a fixed or required rule has
1715 ; no qualifier, then exactly one such AVP MUST
1716 ; be present. If an optional rule has no
1717 ; qualifier, then 0 or 1 such AVP may be
1718 ; present.
1719 ;
1720 ; NOTE: "[" and "]" have a different meaning
1721 ; than in ABNF (see the optional rule, above).
1722 ; These braces cannot be used to express
1723 ; optional fixed rules (such as an optional
1724 ; ICV at the end). To do this, the convention
1725 ; is '0*1fixed'.
1727 min = 1*DIGIT
1728 ; The minimum number of times the element may
1729 ; be present. The default value is zero.
1731 max = 1*DIGIT
1732 ; The maximum number of times the element may
1733 ; be present. The default value is infinity. A
1734 ; value of zero implies the AVP MUST NOT be
1735 ; present.
1737 avp-spec = diameter-name
1738 ; The avp-spec has to be an AVP Name, defined
1739 ; in the base or extended Diameter
1740 ; specifications.
1742 avp-name = avp-spec / "AVP"
1743 ; The string "AVP" stands for *any* arbitrary AVP
1744 ; Name, not otherwise listed in that command code
1745 ; definition.
1747 The following is a definition of a fictitious command code:
1749 Example-Request ::= < Diameter Header: 9999999, REQ, PXY >
1750 { User-Name }
1751 * { Origin-Host }
1752 * [ AVP
1754 3.3. Diameter Command Naming Conventions
1756 Diameter command names typically includes one or more English words
1757 followed by the verb Request or Answer. Each English word is
1758 delimited by a hyphen. A three-letter acronym for both the request
1759 and answer is also normally provided.
1761 An example is a message set used to terminate a session. The command
1762 name is Session-Terminate-Request and Session-Terminate-Answer, while
1763 the acronyms are STR and STA, respectively.
1765 Both the request and the answer for a given command share the same
1766 command code. The request is identified by the R(equest) bit in the
1767 Diameter header set to one (1), to ask that a particular action be
1768 performed, such as authorizing a user or terminating a session. Once
1769 the receiver has completed the request it issues the corresponding
1770 answer, which includes a result code that communicates one of the
1771 following:
1773 o The request was successful
1775 o The request failed
1777 o An additional request must be sent to provide information the peer
1778 requires prior to returning a successful or failed answer.
1780 o The receiver could not process the request, but provides
1781 information about a Diameter peer that is able to satisfy the
1782 request, known as redirect.
1784 Additional information, encoded within AVPs, MAY also be included in
1785 answer messages.
1787 4. Diameter AVPs
1789 Diameter AVPs carry specific authentication, accounting,
1790 authorization and routing information as well as configuration
1791 details for the request and reply.
1793 Some AVPs MAY be listed more than once. The effect of such an AVP is
1794 specific, and is specified in each case by the AVP description.
1796 Each AVP of type OctetString MUST be padded to align on a 32-bit
1797 boundary, while other AVP types align naturally. A number of zero-
1798 valued bytes are added to the end of the AVP Data field till a word
1799 boundary is reached. The length of the padding is not reflected in
1800 the AVP Length field.
1802 4.1. AVP Header
1804 The fields in the AVP header MUST be sent in network byte order. The
1805 format of the header is:
1807 0 1 2 3
1808 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1809 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1810 | AVP Code |
1811 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1812 |V M r r r r r r| AVP Length |
1813 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1814 | Vendor-ID (opt) |
1815 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1816 | Data ...
1817 +-+-+-+-+-+-+-+-+
1819 AVP Code
1821 The AVP Code, combined with the Vendor-Id field, identifies the
1822 attribute uniquely. AVP numbers 1 through 255 are reserved for
1823 backward compatibility with RADIUS, without setting the Vendor-Id
1824 field. AVP numbers 256 and above are used for Diameter, which are
1825 allocated by IANA (see Section 11.1).
1827 AVP Flags
1829 The AVP Flags field informs the receiver how each attribute must
1830 be handled. The 'r' (reserved) bits are unused and SHOULD be set
1831 to 0. Note that subsequent Diameter applications MAY define
1832 additional bits within the AVP Header, and an unrecognized bit
1833 SHOULD be considered an error.
1835 The 'M' Bit, known as the Mandatory bit, indicates whether support
1836 of the AVP is required. If an AVP with the 'M' bit set is
1837 received by a Diameter client, server, proxy, or translation agent
1838 and either the AVP or its value is unrecognized, the message MUST
1839 be rejected. Diameter Relay and redirect agents MUST NOT reject
1840 messages with unrecognized AVPs.
1842 The 'M' bit MUST be set according to the rules defined for the AVP
1843 containing it. In order to preserve interoperability, a Diameter
1844 implementation MUST be able to exclude from a Diameter message any
1845 Mandatory AVP which is neither defined in the base Diameter
1846 protocol nor in any of the Diameter Application specifications
1847 governing the message in which it appears. It MAY do this in one
1848 of the following ways:
1850 1. If a message is rejected because it contains a Mandatory AVP
1851 which is neither defined in the base Diameter standard nor in
1852 any of the Diameter Application specifications governing the
1853 message in which it appears, the implementation may resend the
1854 message without the AVP, possibly inserting additional
1855 standard AVPs instead.
1857 2. A configuration option may be provided on a system wide, per
1858 peer, or per realm basis that would allow/prevent particular
1859 Mandatory AVPs to be sent. Thus an administrator could change
1860 the configuration to avoid interoperability problems.
1862 Diameter implementations are required to support all Mandatory
1863 AVPs which are allowed by the message's formal syntax and defined
1864 either in the base Diameter standard or in one of the Diameter
1865 Application specifications governing the message.
1867 AVPs with the 'M' bit cleared are informational only and a
1868 receiver that receives a message with such an AVP that is not
1869 supported, or whose value is not supported, MAY simply ignore the
1870 AVP.
1872 The 'V' bit, known as the Vendor-Specific bit, indicates whether
1873 the optional Vendor-ID field is present in the AVP header. When
1874 set the AVP Code belongs to the specific vendor code address
1875 space.
1877 Unless otherwise noted, AVPs will have the following default AVP
1878 Flags field settings:
1880 The 'M' bit MUST be set. The 'V' bit MUST NOT be set.
1882 AVP Length
1884 The AVP Length field is three octets, and indicates the number of
1885 octets in this AVP including the AVP Code, AVP Length, AVP Flags,
1886 Vendor-ID field (if present) and the AVP data. If a message is
1887 received with an invalid attribute length, the message SHOULD be
1888 rejected.
1890 4.1.1. Optional Header Elements
1892 The AVP Header contains one optional field. This field is only
1893 present if the respective bit-flag is enabled.
1895 Vendor-ID
1897 The Vendor-ID field is present if the 'V' bit is set in the AVP
1898 Flags field. The optional four-octet Vendor-ID field contains the
1899 IANA assigned "SMI Network Management Private Enterprise Codes"
1900 [RFC3232] value, encoded in network byte order. Any vendor
1901 wishing to implement a vendor-specific Diameter AVP MUST use their
1902 own Vendor-ID along with their privately managed AVP address
1903 space, guaranteeing that they will not collide with any other
1904 vendor's vendor-specific AVP(s), nor with future IETF
1905 applications.
1907 A vendor ID value of zero (0) corresponds to the IETF adopted AVP
1908 values, as managed by the IANA. Since the absence of the vendor
1909 ID field implies that the AVP in question is not vendor specific,
1910 implementations MUST NOT use the zero (0) vendor ID.
1912 4.2. Basic AVP Data Formats
1914 The Data field is zero or more octets and contains information
1915 specific to the Attribute. The format and length of the Data field
1916 is determined by the AVP Code and AVP Length fields. The format of
1917 the Data field MUST be one of the following base data types or a data
1918 type derived from the base data types. In the event that a new Basic
1919 AVP Data Format is needed, a new version of this RFC must be created.
1921 OctetString
1923 The data contains arbitrary data of variable length. Unless
1924 otherwise noted, the AVP Length field MUST be set to at least 8
1925 (12 if the 'V' bit is enabled). AVP Values of this type that are
1926 not a multiple of four-octets in length is followed by the
1927 necessary padding so that the next AVP (if any) will start on a
1928 32-bit boundary.
1930 Integer32
1932 32 bit signed value, in network byte order. The AVP Length field
1933 MUST be set to 12 (16 if the 'V' bit is enabled).
1935 Integer64
1937 64 bit signed value, in network byte order. The AVP Length field
1938 MUST be set to 16 (20 if the 'V' bit is enabled).
1940 Unsigned32
1942 32 bit unsigned value, in network byte order. The AVP Length
1943 field MUST be set to 12 (16 if the 'V' bit is enabled).
1945 Unsigned64
1947 64 bit unsigned value, in network byte order. The AVP Length
1948 field MUST be set to 16 (20 if the 'V' bit is enabled).
1950 Float32
1952 This represents floating point values of single precision as
1953 described by [FLOATPOINT]. The 32-bit value is transmitted in
1954 network byte order. The AVP Length field MUST be set to 12 (16 if
1955 the 'V' bit is enabled).
1957 Float64
1959 This represents floating point values of double precision as
1960 described by [FLOATPOINT]. The 64-bit value is transmitted in
1961 network byte order. The AVP Length field MUST be set to 16 (20 if
1962 the 'V' bit is enabled).
1964 Grouped
1966 The Data field is specified as a sequence of AVPs. Each of these
1967 AVPs follows - in the order in which they are specified -
1968 including their headers and padding. The AVP Length field is set
1969 to 8 (12 if the 'V' bit is enabled) plus the total length of all
1970 included AVPs, including their headers and padding. Thus the AVP
1971 length field of an AVP of type Grouped is always a multiple of 4.
1973 4.3. Derived AVP Data Formats
1975 In addition to using the Basic AVP Data Formats, applications may
1976 define data formats derived from the Basic AVP Data Formats. An
1977 application that defines new AVP Derived Data Formats MUST include
1978 them in a section entitled "AVP Derived Data Formats", using the same
1979 format as the definitions below. Each new definition must be either
1980 defined or listed with a reference to the RFC that defines the
1981 format.
1983 The below AVP Derived Data Formats are commonly used by applications.
1985 Address
1987 The Address format is derived from the OctetString AVP Base
1988 Format. It is a discriminated union, representing, for example a
1989 32-bit (IPv4) [IPV4] or 128-bit (IPv6) [RFC4291] address, most
1990 significant octet first. The first two octets of the Address AVP
1991 represents the AddressType, which contains an Address Family
1992 defined in [IANAADFAM]. The AddressType is used to discriminate
1993 the content and format of the remaining octets.
1995 Time
1997 The Time format is derived from the OctetString AVP Base Format.
1998 The string MUST contain four octets, in the same format as the
1999 first four bytes are in the NTP timestamp format. The NTP
2000 Timestamp format is defined in chapter 3 of [RFC4330].
2002 This represents the number of seconds since 0h on 1 January 1900
2003 with respect to the Coordinated Universal Time (UTC).
2005 On 6h 28m 16s UTC, 7 February 2036 the time value will overflow.
2006 SNTP [RFC4330] describes a procedure to extend the time to 2104.
2007 This procedure MUST be supported by all DIAMETER nodes.
2009 UTF8String
2011 The UTF8String format is derived from the OctetString AVP Base
2012 Format. This is a human readable string represented using the
2013 ISO/IEC IS 10646-1 character set, encoded as an OctetString using
2014 the UTF-8 [RFC3629] transformation format described in RFC 3629.
2016 Since additional code points are added by amendments to the 10646
2017 standard from time to time, implementations MUST be prepared to
2018 encounter any code point from 0x00000001 to 0x7fffffff. Byte
2019 sequences that do not correspond to the valid encoding of a code
2020 point into UTF-8 charset or are outside this range are prohibited.
2022 The use of control codes SHOULD be avoided. When it is necessary
2023 to represent a new line, the control code sequence CR LF SHOULD be
2024 used.
2026 The use of leading or trailing white space SHOULD be avoided.
2028 For code points not directly supported by user interface hardware
2029 or software, an alternative means of entry and display, such as
2030 hexadecimal, MAY be provided.
2032 For information encoded in 7-bit US-ASCII, the UTF-8 charset is
2033 identical to the US-ASCII charset.
2035 UTF-8 may require multiple bytes to represent a single character /
2036 code point; thus the length of an UTF8String in octets may be
2037 different from the number of characters encoded.
2039 Note that the AVP Length field of an UTF8String is measured in
2040 octets, not characters.
2042 DiameterIdentity
2044 The DiameterIdentity format is derived from the OctetString AVP
2045 Base Format.
2047 DiameterIdentity = FQDN
2049 DiameterIdentity value is used to uniquely identify a Diameter
2050 node for purposes of duplicate connection and routing loop
2051 detection.
2053 The contents of the string MUST be the FQDN of the Diameter node.
2054 If multiple Diameter nodes run on the same host, each Diameter
2055 node MUST be assigned a unique DiameterIdentity. If a Diameter
2056 node can be identified by several FQDNs, a single FQDN should be
2057 picked at startup, and used as the only DiameterIdentity for that
2058 node, whatever the connection it is sent on.
2060 DiameterURI
2062 The DiameterURI MUST follow the Uniform Resource Identifiers (URI)
2063 syntax [RFC3986] rules specified below:
2065 "aaa://" FQDN [ port ] [ transport ] [ protocol ]
2067 ; No transport security
2069 "aaas://" FQDN [ port ] [ transport ] [ protocol ]
2071 ; Transport security used
2073 FQDN = Fully Qualified Host Name
2075 port = ":" 1*DIGIT
2077 ; One of the ports used to listen for
2078 ; incoming connections.
2079 ; If absent,
2080 ; the default Diameter port (3868) is
2081 ; assumed.
2083 transport = ";transport=" transport-protocol
2085 ; One of the transports used to listen
2086 ; for incoming connections. If absent,
2087 ; the default SCTP [RFC2960] protocol is
2088 ; assumed. UDP MUST NOT be used when
2089 ; the aaa-protocol field is set to
2090 ; diameter.
2092 transport-protocol = ( "tcp" / "sctp" / "udp" )
2094 protocol = ";protocol=" aaa-protocol
2096 ; If absent, the default AAA protocol
2097 ; is diameter.
2099 aaa-protocol = ( "diameter" / "radius" / "tacacs+" )
2101 The following are examples of valid Diameter host identities:
2103 aaa://host.example.com;transport=tcp
2104 aaa://host.example.com:6666;transport=tcp
2105 aaa://host.example.com;protocol=diameter
2106 aaa://host.example.com:6666;protocol=diameter
2107 aaa://host.example.com:6666;transport=tcp;protocol=diameter
2108 aaa://host.example.com:1813;transport=udp;protocol=radius
2110 Enumerated
2112 Enumerated is derived from the Integer32 AVP Base Format. The
2113 definition contains a list of valid values and their
2114 interpretation and is described in the Diameter application
2115 introducing the AVP.
2117 IPFilterRule
2119 The IPFilterRule format is derived from the OctetString AVP Base
2120 Format. It uses the ASCII charset. Packets may be filtered based
2121 on the following information that is associated with it:
2123 Direction (in or out)
2124 Source and destination IP address (possibly masked)
2125 Protocol
2126 Source and destination port (lists or ranges)
2127 TCP flags
2128 IP fragment flag
2129 IP options
2130 ICMP types
2132 Rules for the appropriate direction are evaluated in order, with
2133 the first matched rule terminating the evaluation. Each packet is
2134 evaluated once. If no rule matches, the packet is dropped if the
2135 last rule evaluated was a permit, and passed if the last rule was
2136 a deny.
2138 IPFilterRule filters MUST follow the format:
2140 action dir proto from src to dst [options]
2142 action permit - Allow packets that match the rule.
2143 deny - Drop packets that match the rule.
2145 dir "in" is from the terminal, "out" is to the
2146 terminal.
2148 proto An IP protocol specified by number. The "ip"
2149 keyword means any protocol will match.
2151 src and dst
[ports]
2153 The may be specified as:
2154 ipno An IPv4 or IPv6 number in dotted-
2155 quad or canonical IPv6 form. Only
2156 this exact IP number will match the
2157 rule.
2158 ipno/bits An IP number as above with a mask
2159 width of the form 1.2.3.4/24. In
2160 this case, all IP numbers from
2161 1.2.3.0 to 1.2.3.255 will match.
2162 The bit width MUST be valid for the
2163 IP version and the IP number MUST
2164 NOT have bits set beyond the mask.
2165 For a match to occur, the same IP
2166 version must be present in the
2167 packet that was used in describing
2168 the IP address. To test for a
2169 particular IP version, the bits part
2170 can be set to zero. The keyword
2171 "any" is 0.0.0.0/0 or the IPv6
2172 equivalent. The keyword "assigned"
2173 is the address or set of addresses
2174 assigned to the terminal. For IPv4,
2175 a typical first rule is often "deny
2176 in ip! assigned"
2178 The sense of the match can be inverted by
2179 preceding an address with the not modifier (!),
2180 causing all other addresses to be matched
2181 instead. This does not affect the selection of
2182 port numbers.
2184 With the TCP, UDP and SCTP protocols, optional
2185 ports may be specified as:
2187 {port/port-port}[,ports[,...]]
2189 The '-' notation specifies a range of ports
2190 (including boundaries).
2192 Fragmented packets that have a non-zero offset
2193 (i.e., not the first fragment) will never match
2194 a rule that has one or more port
2195 specifications. See the frag option for
2196 details on matching fragmented packets.
2198 options:
2199 frag Match if the packet is a fragment and this is not
2200 the first fragment of the datagram. frag may not
2201 be used in conjunction with either tcpflags or
2202 TCP/UDP port specifications.
2204 ipoptions spec
2205 Match if the IP header contains the comma
2206 separated list of options specified in spec. The
2207 supported IP options are:
2209 ssrr (strict source route), lsrr (loose source
2210 route), rr (record packet route) and ts
2211 (timestamp). The absence of a particular option
2212 may be denoted with a '!'.
2214 tcpoptions spec
2215 Match if the TCP header contains the comma
2216 separated list of options specified in spec. The
2217 supported TCP options are:
2219 mss (maximum segment size), window (tcp window
2220 advertisement), sack (selective ack), ts (rfc1323
2221 timestamp) and cc (rfc1644 t/tcp connection
2222 count). The absence of a particular option may
2223 be denoted with a '!'.
2225 established
2226 TCP packets only. Match packets that have the RST
2227 or ACK bits set.
2229 setup TCP packets only. Match packets that have the SYN
2230 bit set but no ACK bit.
2232 tcpflags spec
2233 TCP packets only. Match if the TCP header
2234 contains the comma separated list of flags
2235 specified in spec. The supported TCP flags are:
2237 fin, syn, rst, psh, ack and urg. The absence of a
2238 particular flag may be denoted with a '!'. A rule
2239 that contains a tcpflags specification can never
2240 match a fragmented packet that has a non-zero
2241 offset. See the frag option for details on
2242 matching fragmented packets.
2244 icmptypes types
2245 ICMP packets only. Match if the ICMP type is in
2246 the list types. The list may be specified as any
2247 combination of ranges or individual types
2248 separated by commas. Both the numeric values and
2249 the symbolic values listed below can be used. The
2250 supported ICMP types are:
2252 echo reply (0), destination unreachable (3),
2253 source quench (4), redirect (5), echo request
2254 (8), router advertisement (9), router
2255 solicitation (10), time-to-live exceeded (11), IP
2256 header bad (12), timestamp request (13),
2257 timestamp reply (14), information request (15),
2258 information reply (16), address mask request (17)
2259 and address mask reply (18).
2261 There is one kind of packet that the access device MUST always
2262 discard, that is an IP fragment with a fragment offset of one.
2263 This is a valid packet, but it only has one use, to try to
2264 circumvent firewalls.
2266 An access device that is unable to interpret or apply a deny rule
2267 MUST terminate the session. An access device that is unable to
2268 interpret or apply a permit rule MAY apply a more restrictive
2269 rule. An access device MAY apply deny rules of its own before the
2270 supplied rules, for example to protect the access device owner's
2271 infrastructure.
2273 The rule syntax is a modified subset of ipfw(8) from FreeBSD, and
2274 the ipfw.c code may provide a useful base for implementations.
2276 4.4. Grouped AVP Values
2278 The Diameter protocol allows AVP values of type 'Grouped.' This
2279 implies that the Data field is actually a sequence of AVPs. It is
2280 possible to include an AVP with a Grouped type within a Grouped type,
2281 that is, to nest them. AVPs within an AVP of type Grouped have the
2282 same padding requirements as non-Grouped AVPs, as defined in Section
2283 4.
2285 The AVP Code numbering space of all AVPs included in a Grouped AVP is
2286 the same as for non-grouped AVPs. Further, if any of the AVPs
2287 encapsulated within a Grouped AVP has the 'M' (mandatory) bit set,
2288 the Grouped AVP itself MUST also include the 'M' bit set.
2290 Every Grouped AVP defined MUST include a corresponding grammar, using
2291 ABNF [RFC4234] (with modifications), as defined below.
2293 grouped-avp-def = name "::=" avp
2295 name-fmt = ALPHA *(ALPHA / DIGIT / "-")
2297 name = name-fmt
2298 ; The name has to be the name of an AVP,
2299 ; defined in the base or extended Diameter
2300 ; specifications.
2302 avp = header [ *fixed] [ *required] [ *optional]
2303 [ *fixed]
2305 header = "<" "AVP-Header:" avpcode [vendor] ">"
2307 avpcode = 1*DIGIT
2308 ; The AVP Code assigned to the Grouped AVP
2310 vendor = 1*DIGIT
2311 ; The Vendor-ID assigned to the Grouped AVP.
2312 ; If absent, the default value of zero is
2313 ; used.
2315 4.4.1. Example AVP with a Grouped Data type
2317 The Example-AVP (AVP Code 999999) is of type Grouped and is used to
2318 clarify how Grouped AVP values work. The Grouped Data field has the
2319 following ABNF grammar:
2321 Example-AVP ::= < AVP Header: 999999 >
2322 { Origin-Host }
2323 1*{ Session-Id }
2324 *[ AVP ]
2326 An Example-AVP with Grouped Data follows.
2328 The Origin-Host AVP is required (Section 6.3). In this case:
2330 Origin-Host = "example.com".
2332 One or more Session-Ids must follow. Here there are two:
2334 Session-Id =
2335 "grump.example.com:33041;23432;893;0AF3B81"
2337 Session-Id =
2338 "grump.example.com:33054;23561;2358;0AF3B82"
2340 optional AVPs included are
2342 Recovery-Policy =
2343 2163bc1d0ad82371f6bc09484133c3f09ad74a0dd5346d54195a7cf0b35
2344 2cabc881839a4fdcfbc1769e2677a4c1fb499284c5f70b48f58503a45c5
2345 c2d6943f82d5930f2b7c1da640f476f0e9c9572a50db8ea6e51e1c2c7bd
2346 f8bb43dc995144b8dbe297ac739493946803e1cee3e15d9b765008a1b2a
2347 cf4ac777c80041d72c01e691cf751dbf86e85f509f3988e5875dc905119
2348 26841f00f0e29a6d1ddc1a842289d440268681e052b30fb638045f7779c
2349 1d873c784f054f688f5001559ecff64865ef975f3e60d2fd7966b8c7f92
2351 Futuristic-Acct-Record =
2352 fe19da5802acd98b07a5b86cb4d5d03f0314ab9ef1ad0b67111ff3b90a0
2353 57fe29620bf3585fd2dd9fcc38ce62f6cc208c6163c008f4258d1bc88b8
2354 17694a74ccad3ec69269461b14b2e7a4c111fb239e33714da207983f58c
2355 41d018d56fe938f3cbf089aac12a912a2f0d1923a9390e5f789cb2e5067
2356 d3427475e49968f841
2358 The data for the optional AVPs is represented in hex since the format
2359 of these AVPs is neither known at the time of definition of the
2360 Example-AVP group, nor (likely) at the time when the example instance
2361 of this AVP is interpreted - except by Diameter implementations which
2362 support the same set of AVPs. The encoding example illustrates how
2363 padding is used and how length fields are calculated. Also note that
2364 AVPs may be present in the Grouped AVP value which the receiver
2365 cannot interpret (here, the Recover-Policy and Futuristic-Acct-Record
2366 AVPs). The length of the Example-AVP is the sum of all the length of
2367 the member AVPs including their padding plus the Example-AVP header
2368 size.
2370 This AVP would be encoded as follows:
2372 0 1 2 3 4 5 6 7
2373 +-------+-------+-------+-------+-------+-------+-------+-------+
2374 0 | Example AVP Header (AVP Code = 999999), Length = 496 |
2375 +-------+-------+-------+-------+-------+-------+-------+-------+
2376 8 | Origin-Host AVP Header (AVP Code = 264), Length = 19 |
2377 +-------+-------+-------+-------+-------+-------+-------+-------+
2378 16 | 'e' | 'x' | 'a' | 'm' | 'p' | 'l' | 'e' | '.' |
2379 +-------+-------+-------+-------+-------+-------+-------+-------+
2380 24 | 'c' | 'o' | 'm' |Padding| Session-Id AVP Header |
2381 +-------+-------+-------+-------+-------+-------+-------+-------+
2382 32 | (AVP Code = 263), Length = 49 | 'g' | 'r' | 'u' | 'm' |
2383 +-------+-------+-------+-------+-------+-------+-------+-------+
2384 . . .
2385 +-------+-------+-------+-------+-------+-------+-------+-------+
2386 72 | 'F' | '3' | 'B' | '8' | '1' |Padding|Padding|Padding|
2387 +-------+-------+-------+-------+-------+-------+-------+-------+
2388 80 | Session-Id AVP Header (AVP Code = 263), Length = 50 |
2389 +-------+-------+-------+-------+-------+-------+-------+-------+
2390 88 | 'g' | 'r' | 'u' | 'm' | 'p' | '.' | 'e' | 'x' |
2391 +-------+-------+-------+-------+-------+-------+-------+-------+
2392 . . .
2393 +-------+-------+-------+-------+-------+-------+-------+-------+
2394 120| '5' | '8' | ';' | '0' | 'A' | 'F' | '3' | 'B' |
2395 +-------+-------+-------+-------+-------+-------+-------+-------+
2396 128| '8' | '2' |Padding|Padding| Recovery-Policy Header (AVP |
2397 +-------+-------+-------+-------+-------+-------+-------+-------+
2398 136| Code = 8341), Length = 223 | 0x21 | 0x63 | 0xbc | 0x1d |
2399 +-------+-------+-------+-------+-------+-------+-------+-------+
2400 144| 0x0a | 0xd8 | 0x23 | 0x71 | 0xf6 | 0xbc | 0x09 | 0x48 |
2401 +-------+-------+-------+-------+-------+-------+-------+-------+
2402 . . .
2403 +-------+-------+-------+-------+-------+-------+-------+-------+
2404 352| 0x8c | 0x7f | 0x92 |Padding| Futuristic-Acct-Record Header |
2405 +-------+-------+-------+-------+-------+-------+-------+-------+
2406 328|(AVP Code = 15930),Length = 137| 0xfe | 0x19 | 0xda | 0x58 |
2407 +-------+-------+-------+-------+-------+-------+-------+-------+
2408 336| 0x02 | 0xac | 0xd9 | 0x8b | 0x07 | 0xa5 | 0xb8 | 0xc6 |
2409 +-------+-------+-------+-------+-------+-------+-------+-------+
2410 . . .
2411 +-------+-------+-------+-------+-------+-------+-------+-------+
2412 488| 0xe4 | 0x99 | 0x68 | 0xf8 | 0x41 |Padding|Padding|Padding|
2413 +-------+-------+-------+-------+-------+-------+-------+-------+
2415 4.5. Diameter Base Protocol AVPs
2417 The following table describes the Diameter AVPs defined in the base
2418 protocol, their AVP Code values, types, possible flag values.
2420 Due to space constraints, the short form DiamIdent is used to
2421 represent DiameterIdentity.
2423 +---------------------+
2424 | AVP Flag rules |
2425 |----+-----+----+-----|
2426 AVP Section | | |SHLD| MUST|
2427 Attribute Name Code Defined Data Type |MUST| MAY | NOT| NOT|
2428 -----------------------------------------|----+-----+----+-----|
2429 Acct- 85 9.8.2 Unsigned32 | M | | | V |
2430 Interim-Interval | | | | |
2431 Accounting- 483 9.8.7 Enumerated | M | | | V |
2432 Realtime-Required | | | | |
2433 Acct- 50 9.8.5 UTF8String | M | | | V |
2434 Multi-Session-Id | | | | |
2435 Accounting- 485 9.8.3 Unsigned32 | M | | | V |
2436 Record-Number | | | | |
2437 Accounting- 480 9.8.1 Enumerated | M | | | V |
2438 Record-Type | | | | |
2439 Accounting- 44 9.8.4 OctetString| M | | | V |
2440 Session-Id | | | | |
2441 Accounting- 287 9.8.6 Unsigned64 | M | | | V |
2442 Sub-Session-Id | | | | |
2443 Acct- 259 6.9 Unsigned32 | M | | | V |
2444 Application-Id | | | | |
2445 Auth- 258 6.8 Unsigned32 | M | | | V |
2446 Application-Id | | | | |
2447 Auth-Request- 274 8.7 Enumerated | M | | | V |
2448 Type | | | | |
2449 Authorization- 291 8.9 Unsigned32 | M | | | V |
2450 Lifetime | | | | |
2451 Auth-Grace- 276 8.10 Unsigned32 | M | | | V |
2452 Period | | | | |
2453 Auth-Session- 277 8.11 Enumerated | M | | | V |
2454 State | | | | |
2455 Re-Auth-Request- 285 8.12 Enumerated | M | | | V |
2456 Type | | | | |
2457 Class 25 8.20 OctetString| M | | | V |
2458 Destination-Host 293 6.5 DiamIdent | M | | | V |
2459 Destination- 283 6.6 DiamIdent | M | | | V |
2460 Realm | | | | |
2461 Disconnect-Cause 273 5.4.3 Enumerated | M | | | V |
2462 E2E-Sequence AVP 300 6.15 Grouped | M | | | V |
2463 Error-Message 281 7.3 UTF8String | | | | V,M |
2464 Error-Reporting- 294 7.4 DiamIdent | | | | V,M |
2465 Host | | | | |
2466 Event-Timestamp 55 8.21 Time | M | | | V |
2467 Experimental- 297 7.6 Grouped | M | | | V |
2468 Result | | | | |
2469 -----------------------------------------|----+-----+----+-----|
2470 +---------------------+
2471 | AVP Flag rules |
2472 |----+-----+----+-----|
2473 AVP Section | | |SHLD| MUST|
2474 Attribute Name Code Defined Data Type |MUST| MAY | NOT| NOT|
2475 -----------------------------------------|----+-----+----+-----|
2476 Experimental- 298 7.7 Unsigned32 | M | | | V |
2477 Result-Code | | | | |
2478 Failed-AVP 279 7.5 Grouped | M | | | V |
2479 Firmware- 267 5.3.4 Unsigned32 | | | | V,M |
2480 Revision | | | | |
2481 Host-IP-Address 257 5.3.5 Address | M | | | V |
2482 Inband-Security | M | | | V |
2483 -Id 299 6.10 Unsigned32 | | | | |
2484 Multi-Round- 272 8.19 Unsigned32 | M | | | V |
2485 Time-Out | | | | |
2486 Origin-Host 264 6.3 DiamIdent | M | | | V |
2487 Origin-Realm 296 6.4 DiamIdent | M | | | V |
2488 Origin-State-Id 278 8.16 Unsigned32 | M | | | V |
2489 Product-Name 269 5.3.7 UTF8String | | | | V,M |
2490 Proxy-Host 280 6.7.3 DiamIdent | M | | | V |
2491 Proxy-Info 284 6.7.2 Grouped | M | | | V |
2492 Proxy-State 33 6.7.4 OctetString| M | | | V |
2493 Redirect-Host 292 6.12 DiamURI | M | | | V |
2494 Redirect-Host- 261 6.13 Enumerated | M | | | V |
2495 Usage | | | | |
2496 Redirect-Max- 262 6.14 Unsigned32 | M | | | V |
2497 Cache-Time | | | | |
2498 Result-Code 268 7.1 Unsigned32 | M | | | V |
2499 Route-Record 282 6.7.1 DiamIdent | M | | | V |
2500 Session-Id 263 8.8 UTF8String | M | | | V |
2501 Session-Timeout 27 8.13 Unsigned32 | M | | | V |
2502 Session-Binding 270 8.17 Unsigned32 | M | | | V |
2503 Session-Server- 271 8.18 Enumerated | M | | | V |
2504 Failover | | | | |
2505 Supported- 265 5.3.6 Unsigned32 | M | | | V |
2506 Vendor-Id | | | | |
2507 Termination- 295 8.15 Enumerated | M | | | V |
2508 Cause | | | | |
2509 User-Name 1 8.14 UTF8String | M | | | V |
2510 Vendor-Id 266 5.3.3 Unsigned32 | M | | | V |
2511 Vendor-Specific- 260 6.11 Grouped | M | | | V |
2512 Application-Id | | | | |
2513 -----------------------------------------|----+-----+----+-----|
2515 5. Diameter Peers
2517 This section describes how Diameter nodes establish connections and
2518 communicate with peers.
2520 5.1. Peer Connections
2522 Although a Diameter node may have many possible peers that it is able
2523 to communicate with, it may not be economical to have an established
2524 connection to all of them. At a minimum, a Diameter node SHOULD have
2525 an established connection with two peers per realm, known as the
2526 primary and secondary peers. Of course, a node MAY have additional
2527 connections, if it is deemed necessary. Typically, all messages for
2528 a realm are sent to the primary peer, but in the event that failover
2529 procedures are invoked, any pending requests are sent to the
2530 secondary peer. However, implementations are free to load balance
2531 requests between a set of peers.
2533 Note that a given peer MAY act as a primary for a given realm, while
2534 acting as a secondary for another realm.
2536 When a peer is deemed suspect, which could occur for various reasons,
2537 including not receiving a DWA within an allotted timeframe, no new
2538 requests should be forwarded to the peer, but failover procedures are
2539 invoked. When an active peer is moved to this mode, additional
2540 connections SHOULD be established to ensure that the necessary number
2541 of active connections exists.
2543 There are two ways that a peer is removed from the suspect peer list:
2545 1. The peer is no longer reachable, causing the transport connection
2546 to be shutdown. The peer is moved to the closed state.
2548 2. Three watchdog messages are exchanged with accepted round trip
2549 times, and the connection to the peer is considered stabilized.
2551 In the event the peer being removed is either the primary or
2552 secondary, an alternate peer SHOULD replace the deleted peer, and
2553 assume the role of either primary or secondary.
2555 5.2. Diameter Peer Discovery
2557 Allowing for dynamic Diameter agent discovery will make it possible
2558 for simpler and more robust deployment of Diameter services. In
2559 order to promote interoperable implementations of Diameter peer
2560 discovery, the following mechanisms are described. These are based
2561 on existing IETF standards. The first option (manual configuration)
2562 MUST be supported by all DIAMETER nodes, while the latter option
2563 (DNS) MAY be supported.
2565 There are two cases where Diameter peer discovery may be performed.
2566 The first is when a Diameter client needs to discover a first-hop
2567 Diameter agent. The second case is when a Diameter agent needs to
2568 discover another agent - for further handling of a Diameter
2569 operation. In both cases, the following 'search order' is
2570 recommended:
2572 1. The Diameter implementation consults its list of static
2573 (manually) configured Diameter agent locations. These will be
2574 used if they exist and respond.
2576 2. The Diameter implementation performs a NAPTR query for a server
2577 in a particular realm. The Diameter implementation has to know
2578 in advance which realm to look for a Diameter agent in. This
2579 could be deduced, for example, from the 'realm' in a NAI that a
2580 Diameter implementation needed to perform a Diameter operation
2581 on.
2583 * The services relevant for the task of transport protocol
2584 selection are those with NAPTR service fields with values
2585 "AAA+D2x", where x is a letter that corresponds to a transport
2586 protocol supported by the domain. This specification defines
2587 D2T for TCP and D2S for SCTP. We also establish an IANA
2588 registry for NAPTR service name to transport protocol
2589 mappings.
2591 These NAPTR records provide a mapping from a domain, to the
2592 SRV record for contacting a server with the specific transport
2593 protocol in the NAPTR services field. The resource record
2594 will contain an empty regular expression and a replacement
2595 value, which is the SRV record for that particular transport
2596 protocol. If the server supports multiple transport
2597 protocols, there will be multiple NAPTR records, each with a
2598 different service value. As per [RFC3403], the client
2599 discards any records whose services fields are not applicable.
2600 For the purposes of this specification, several rules are
2601 defined.
2603 * A client MUST discard any service fields that identify a
2604 resolution service whose value is not "D2X", for values of X
2605 that indicate transport protocols supported by the client.
2606 The NAPTR processing as described in [RFC3403] will result in
2607 discovery of the most preferred transport protocol of the
2608 server that is supported by the client, as well as an SRV
2609 record for the server.
2611 The domain suffixes in the NAPTR replacement field SHOULD
2612 match the domain of the original query.
2614 3. If no NAPTR records are found, the requester queries for those
2615 address records for the destination address,
2616 '_diameter._sctp'.realm or '_diameter._tcp'.realm. Address
2617 records include A RR's, AAAA RR's or other similar records,
2618 chosen according to the requestor's network protocol
2619 capabilities. If the DNS server returns no address records, the
2620 requestor gives up.
2622 If the server is using a site certificate, the domain name in the
2623 query and the domain name in the replacement field MUST both be
2624 valid based on the site certificate handed out by the server in
2625 the TLS or IKE exchange. Similarly, the domain name in the SRV
2626 query and the domain name in the target in the SRV record MUST
2627 both be valid based on the same site certificate. Otherwise, an
2628 attacker could modify the DNS records to contain replacement
2629 values in a different domain, and the client could not validate
2630 that this was the desired behavior, or the result of an attack
2632 Also, the Diameter Peer MUST check to make sure that the
2633 discovered peers are authorized to act in its role.
2634 Authentication via IKE or TLS, or validation of DNS RRs via
2635 DNSSEC is not sufficient to conclude this. For example, a web
2636 server may have obtained a valid TLS certificate, and secured RRs
2637 may be included in the DNS, but this does not imply that it is
2638 authorized to act as a Diameter Server.
2640 Authorization can be achieved for example, by configuration of a
2641 Diameter Server CA. Alternatively this can be achieved by
2642 definition of OIDs within TLS or IKE certificates so as to
2643 signify Diameter Server authorization.
2645 A dynamically discovered peer causes an entry in the Peer Table (see
2646 Section 2.6) to be created. Note that entries created via DNS MUST
2647 expire (or be refreshed) within the DNS TTL. If a peer is discovered
2648 outside of the local realm, a routing table entry (see Section 2.7)
2649 for the peer's realm is created. The routing table entry's
2650 expiration MUST match the peer's expiration value.
2652 5.3. Capabilities Exchange
2654 When two Diameter peers establish a transport connection, they MUST
2655 exchange the Capabilities Exchange messages, as specified in the peer
2656 state machine (see Section 5.6). This message allows the discovery
2657 of a peer's identity and its capabilities (protocol version number,
2658 supported Diameter applications, security mechanisms, etc.)
2660 The receiver only issues commands to its peers that have advertised
2661 support for the Diameter application that defines the command. A
2662 Diameter node MUST cache the supported applications in order to
2663 ensure that unrecognized commands and/or AVPs are not unnecessarily
2664 sent to a peer.
2666 A receiver of a Capabilities-Exchange-Req (CER) message that does not
2667 have any applications in common with the sender MUST return a
2668 Capabilities-Exchange-Answer (CEA) with the Result-Code AVP set to
2669 DIAMETER_NO_COMMON_APPLICATION, and SHOULD disconnect the transport
2670 layer connection. Note that receiving a CER or CEA from a peer
2671 advertising itself as a Relay (see Section 2.4) MUST be interpreted
2672 as having common applications with the peer.
2674 The receiver of the Capabilities-Exchange-Request (CER) MUST
2675 determine common applications by computing the intersection of its
2676 own set of supported application identifiers against all of the
2677 application indentifier AVPs (Auth-Application-Id,
2678 Acct-Application-Id and Vendor-Specific-Application-Id) present in
2679 the CER. The value of the Vendor-Id AVP in the Vendor-Specific-
2680 Application-Id MUST not be used during computation. The sender of
2681 the Capabilities-Exchange-Answer (CEA) SHOULD include all of its
2682 supported applications as a hint to the receiver regarding all of its
2683 application capabilities.
2685 Similarly, a receiver of a Capabilities-Exchange-Req (CER) message
2686 that does not have any security mechanisms in common with the sender
2687 MUST return a Capabilities-Exchange-Answer (CEA) with the Result-Code
2688 AVP set to DIAMETER_NO_COMMON_SECURITY, and SHOULD disconnect the
2689 transport layer connection.
2691 CERs received from unknown peers MAY be silently discarded, or a CEA
2692 MAY be issued with the Result-Code AVP set to DIAMETER_UNKNOWN_PEER.
2693 In both cases, the transport connection is closed. If the local
2694 policy permits receiving CERs from unknown hosts, a successful CEA
2695 MAY be returned. If a CER from an unknown peer is answered with a
2696 successful CEA, the lifetime of the peer entry is equal to the
2697 lifetime of the transport connection. In case of a transport
2698 failure, all the pending transactions destined to the unknown peer
2699 can be discarded.
2701 The CER and CEA messages MUST NOT be proxied, redirected or relayed.
2703 Since the CER/CEA messages cannot be proxied, it is still possible
2704 that an upstream agent receives a message for which it has no
2705 available peers to handle the application that corresponds to the
2706 Command-Code. In such instances, the 'E' bit is set in the answer
2707 message (see Section 7.) with the Result-Code AVP set to
2708 DIAMETER_UNABLE_TO_DELIVER to inform the downstream to take action
2709 (e.g., re-routing request to an alternate peer).
2711 With the exception of the Capabilities-Exchange-Request message, a
2712 message of type Request that includes the Auth-Application-Id or
2713 Acct-Application-Id AVPs, or a message with an application-specific
2714 command code, MAY only be forwarded to a host that has explicitly
2715 advertised support for the application (or has advertised the Relay
2716 Application Identifier).
2718 5.3.1. Capabilities-Exchange-Request
2720 The Capabilities-Exchange-Request (CER), indicated by the Command-
2721 Code set to 257 and the Command Flags' 'R' bit set, is sent to
2722 exchange local capabilities. Upon detection of a transport failure,
2723 this message MUST NOT be sent to an alternate peer.
2725 When Diameter is run over SCTP [RFC2960], which allows for
2726 connections to span multiple interfaces and multiple IP addresses,
2727 the Capabilities-Exchange-Request message MUST contain one Host-IP-
2728 Address AVP for each potential IP address that MAY be locally used
2729 when transmitting Diameter messages.
2731 Message Format
2733 ::= < Diameter Header: 257, REQ >
2734 { Origin-Host }
2735 { Origin-Realm }
2736 1* { Host-IP-Address }
2737 { Vendor-Id }
2738 { Product-Name }
2739 [ Origin-State-Id ]
2740 * [ Supported-Vendor-Id ]
2741 * [ Auth-Application-Id ]
2742 * [ Inband-Security-Id ]
2743 * [ Acct-Application-Id ]
2744 * [ Vendor-Specific-Application-Id ]
2745 [ Firmware-Revision ]
2746 * [ AVP ]
2748 5.3.2. Capabilities-Exchange-Answer
2750 The Capabilities-Exchange-Answer (CEA), indicated by the Command-Code
2751 set to 257 and the Command Flags' 'R' bit cleared, is sent in
2752 response to a CER message.
2754 When Diameter is run over SCTP [RFC2960], which allows connections to
2755 span multiple interfaces, hence, multiple IP addresses, the
2756 Capabilities-Exchange-Answer message MUST contain one Host-IP-Address
2757 AVP for each potential IP address that MAY be locally used when
2758 transmitting Diameter messages.
2760 Message Format
2762 ::= < Diameter Header: 257 >
2763 { Result-Code }
2764 { Origin-Host }
2765 { Origin-Realm }
2766 1* { Host-IP-Address }
2767 { Vendor-Id }
2768 { Product-Name }
2769 [ Origin-State-Id ]
2770 [ Error-Message ]
2771 [ Failed-AVP ]
2772 * [ Supported-Vendor-Id ]
2773 * [ Auth-Application-Id ]
2774 * [ Inband-Security-Id ]
2775 * [ Acct-Application-Id ]
2776 * [ Vendor-Specific-Application-Id ]
2777 [ Firmware-Revision ]
2778 * [ AVP ]
2780 5.3.3. Vendor-Id AVP
2782 The Vendor-Id AVP (AVP Code 266) is of type Unsigned32 and contains
2783 the IANA "SMI Network Management Private Enterprise Codes" [RFC3232]
2784 value assigned to the vendor of the Diameter device. It is
2785 envisioned that the combination of the Vendor-Id, Product-Name
2786 (Section 5.3.7) and the Firmware-Revision (Section 5.3.4) AVPs may
2787 provide useful debugging information.
2789 A Vendor-Id value of zero in the CER or CEA messages is reserved and
2790 indicates that this field is ignored.
2792 5.3.4. Firmware-Revision AVP
2794 The Firmware-Revision AVP (AVP Code 267) is of type Unsigned32 and is
2795 used to inform a Diameter peer of the firmware revision of the
2796 issuing device.
2798 For devices that do not have a firmware revision (general purpose
2799 computers running Diameter software modules, for instance), the
2800 revision of the Diameter software module may be reported instead.
2802 5.3.5. Host-IP-Address AVP
2804 The Host-IP-Address AVP (AVP Code 257) is of type Address and is used
2805 to inform a Diameter peer of the sender's IP address. All source
2806 addresses that a Diameter node expects to use with SCTP [RFC2960]
2807 MUST be advertised in the CER and CEA messages by including a
2808 Host-IP- Address AVP for each address. This AVP MUST ONLY be used in
2809 the CER and CEA messages.
2811 5.3.6. Supported-Vendor-Id AVP
2813 The Supported-Vendor-Id AVP (AVP Code 265) is of type Unsigned32 and
2814 contains the IANA "SMI Network Management Private Enterprise Codes"
2815 [RFC3232] value assigned to a vendor other than the device vendor but
2816 including the application vendor. This is used in the CER and CEA
2817 messages in order to inform the peer that the sender supports (a
2818 subset of) the vendor-specific AVPs defined by the vendor identified
2819 in this AVP. The value of this AVP SHOULD NOT be set to zero.
2820 Multiple instances of this AVP containing the same value SHOULD NOT
2821 be sent.
2823 5.3.7. Product-Name AVP
2825 The Product-Name AVP (AVP Code 269) is of type UTF8String, and
2826 contains the vendor assigned name for the product. The Product-Name
2827 AVP SHOULD remain constant across firmware revisions for the same
2828 product.
2830 5.4. Disconnecting Peer connections
2832 When a Diameter node disconnects one of its transport connections,
2833 its peer cannot know the reason for the disconnect, and will most
2834 likely assume that a connectivity problem occurred, or that the peer
2835 has rebooted. In these cases, the peer may periodically attempt to
2836 reconnect, as stated in Section 2.1. In the event that the
2837 disconnect was a result of either a shortage of internal resources,
2838 or simply that the node in question has no intentions of forwarding
2839 any Diameter messages to the peer in the foreseeable future, a
2840 periodic connection request would not be welcomed. The
2841 Disconnection-Reason AVP contains the reason the Diameter node issued
2842 the Disconnect-Peer-Request message.
2844 The Disconnect-Peer-Request message is used by a Diameter node to
2845 inform its peer of its intent to disconnect the transport layer, and
2846 that the peer shouldn't reconnect unless it has a valid reason to do
2847 so (e.g., message to be forwarded). Upon receipt of the message, the
2848 Disconnect-Peer-Answer is returned, which SHOULD contain an error if
2849 messages have recently been forwarded, and are likely in flight,
2850 which would otherwise cause a race condition.
2852 The receiver of the Disconnect-Peer-Answer initiates the transport
2853 disconnect. The sender of the Disconnect-Peer-Answer should be able
2854 to detect the transport closure and cleanup the connection.
2856 5.4.1. Disconnect-Peer-Request
2858 The Disconnect-Peer-Request (DPR), indicated by the Command-Code set
2859 to 282 and the Command Flags' 'R' bit set, is sent to a peer to
2860 inform its intentions to shutdown the transport connection. Upon
2861 detection of a transport failure, this message MUST NOT be sent to an
2862 alternate peer.
2864 Message Format
2866 ::= < Diameter Header: 282, REQ >
2867 { Origin-Host }
2868 { Origin-Realm }
2869 { Disconnect-Cause }
2871 5.4.2. Disconnect-Peer-Answer
2873 The Disconnect-Peer-Answer (DPA), indicated by the Command-Code set
2874 to 282 and the Command Flags' 'R' bit cleared, is sent as a response
2875 to the Disconnect-Peer-Request message. Upon receipt of this
2876 message, the transport connection is shutdown.
2878 Message Format
2880 ::= < Diameter Header: 282 >
2881 { Result-Code }
2882 { Origin-Host }
2883 { Origin-Realm }
2884 [ Error-Message ]
2885 [ Failed-AVP ]
2887 5.4.3. Disconnect-Cause AVP
2889 The Disconnect-Cause AVP (AVP Code 273) is of type Enumerated. A
2890 Diameter node MUST include this AVP in the Disconnect-Peer-Request
2891 message to inform the peer of the reason for its intention to
2892 shutdown the transport connection. The following values are
2893 supported:
2895 REBOOTING 0
2896 A scheduled reboot is imminent. Receiver of DPR with above result
2897 code MAY attempt reconnection.
2899 BUSY 1
2900 The peer's internal resources are constrained, and it has
2901 determined that the transport connection needs to be closed.
2902 Receiver of DPR with above result code SHOULD NOT attempt
2903 reconnection.
2905 DO_NOT_WANT_TO_TALK_TO_YOU 2
2906 The peer has determined that it does not see a need for the
2907 transport connection to exist, since it does not expect any
2908 messages to be exchanged in the near future. Receiver of DPR
2909 with above result code SHOULD NOT attempt reconnection.
2911 5.5. Transport Failure Detection
2913 Given the nature of the Diameter protocol, it is recommended that
2914 transport failures be detected as soon as possible. Detecting such
2915 failures will minimize the occurrence of messages sent to unavailable
2916 agents, resulting in unnecessary delays, and will provide better
2917 failover performance. The Device-Watchdog-Request and Device-
2918 Watchdog-Answer messages, defined in this section, are used to pro-
2919 actively detect transport failures.
2921 5.5.1. Device-Watchdog-Request
2923 The Device-Watchdog-Request (DWR), indicated by the Command-Code set
2924 to 280 and the Command Flags' 'R' bit set, is sent to a peer when no
2925 traffic has been exchanged between two peers (see Section 5.5.3).
2926 Upon detection of a transport failure, this message MUST NOT be sent
2927 to an alternate peer.
2929 Message Format
2931 ::= < Diameter Header: 280, REQ >
2932 { Origin-Host }
2933 { Origin-Realm }
2934 [ Origin-State-Id ]
2936 5.5.2. Device-Watchdog-Answer
2938 The Device-Watchdog-Answer (DWA), indicated by the Command-Code set
2939 to 280 and the Command Flags' 'R' bit cleared, is sent as a response
2940 to the Device-Watchdog-Request message.
2942 Message Format
2944 ::= < Diameter Header: 280 >
2945 { Result-Code }
2946 { Origin-Host }
2947 { Origin-Realm }
2948 [ Error-Message ]
2949 [ Failed-AVP ]
2950 [ Origin-State-Id ]
2952 5.5.3. Transport Failure Algorithm
2954 The transport failure algorithm is defined in [RFC3539]. All
2955 Diameter implementations MUST support the algorithm defined in the
2956 specification in order to be compliant to the Diameter base protocol.
2958 5.5.4. Failover and Failback Procedures
2960 In the event that a transport failure is detected with a peer, it is
2961 necessary for all pending request messages to be forwarded to an
2962 alternate agent, if possible. This is commonly referred to as
2963 failover.
2965 In order for a Diameter node to perform failover procedures, it is
2966 necessary for the node to maintain a pending message queue for a
2967 given peer. When an answer message is received, the corresponding
2968 request is removed from the queue. The Hop-by-Hop Identifier field
2969 is used to match the answer with the queued request.
2971 When a transport failure is detected, if possible all messages in the
2972 queue are sent to an alternate agent with the T flag set. On booting
2973 a Diameter client or agent, the T flag is also set on any records
2974 still remaining to be transmitted in non-volatile storage. An
2975 example of a case where it is not possible to forward the message to
2976 an alternate server is when the message has a fixed destination, and
2977 the unavailable peer is the message's final destination (see
2978 Destination-Host AVP). Such an error requires that the agent return
2979 an answer message with the 'E' bit set and the Result-Code AVP set to
2980 DIAMETER_UNABLE_TO_DELIVER.
2982 It is important to note that multiple identical requests or answers
2983 MAY be received as a result of a failover. The End-to-End Identifier
2984 field in the Diameter header along with the Origin-Host AVP MUST be
2985 used to identify duplicate messages.
2987 As described in Section 2.1, a connection request should be
2988 periodically attempted with the failed peer in order to re-establish
2989 the transport connection. Once a connection has been successfully
2990 established, messages can once again be forwarded to the peer. This
2991 is commonly referred to as failback.
2993 5.6. Peer State Machine
2995 This section contains a finite state machine that MUST be observed by
2996 all Diameter implementations. Each Diameter node MUST follow the
2997 state machine described below when communicating with each peer.
2998 Multiple actions are separated by commas, and may continue on
2999 succeeding lines, as space requires. Similarly, state and next state
3000 may also span multiple lines, as space requires.
3002 This state machine is closely coupled with the state machine
3003 described in [RFC3539], which is used to open, close, failover,
3004 probe, and reopen transport connections. Note in particular that
3005 [RFC3539] requires the use of watchdog messages to probe connections.
3006 For Diameter, DWR and DWA messages are to be used.
3008 I- is used to represent the initiator (connecting) connection, while
3009 the R- is used to represent the responder (listening) connection.
3010 The lack of a prefix indicates that the event or action is the same
3011 regardless of the connection on which the event occurred.
3013 The stable states that a state machine may be in are Closed, I-Open
3014 and R-Open; all other states are intermediate. Note that I-Open and
3015 R-Open are equivalent except for whether the initiator or responder
3016 transport connection is used for communication.
3018 A CER message is always sent on the initiating connection immediately
3019 after the connection request is successfully completed. In the case
3020 of an election, one of the two connections will shut down. The
3021 responder connection will survive if the Origin-Host of the local
3022 Diameter entity is higher than that of the peer; the initiator
3023 connection will survive if the peer's Origin-Host is higher. All
3024 subsequent messages are sent on the surviving connection. Note that
3025 the results of an election on one peer are guaranteed to be the
3026 inverse of the results on the other.
3028 For TLS usage, a TLS handshake will begin when both ends are in the
3029 open state. If the TLS handshake is successful, all further messages
3030 will be sent via TLS. If the handshake fails, both ends move to the
3031 closed state.
3033 The state machine constrains only the behavior of a Diameter
3034 implementation as seen by Diameter peers through events on the wire.
3036 Any implementation that produces equivalent results is considered
3037 compliant.
3039 state event action next state
3040 -----------------------------------------------------------------
3041 Closed Start I-Snd-Conn-Req Wait-Conn-Ack
3042 R-Conn-CER R-Accept, R-Open
3043 Process-CER,
3044 R-Snd-CEA
3046 Wait-Conn-Ack I-Rcv-Conn-Ack I-Snd-CER Wait-I-CEA
3047 I-Rcv-Conn-Nack Cleanup Closed
3048 R-Conn-CER R-Accept, Wait-Conn-Ack/
3049 Process-CER Elect
3050 Timeout Error Closed
3052 Wait-I-CEA I-Rcv-CEA Process-CEA I-Open
3053 R-Conn-CER R-Accept, Wait-Returns
3054 Process-CER,
3055 Elect
3056 I-Peer-Disc I-Disc Closed
3057 I-Rcv-Non-CEA Error Closed
3058 Timeout Error Closed
3060 Wait-Conn-Ack/ I-Rcv-Conn-Ack I-Snd-CER,Elect Wait-Returns
3061 Elect I-Rcv-Conn-Nack R-Snd-CEA R-Open
3062 R-Peer-Disc R-Disc Wait-Conn-Ack
3063 R-Conn-CER R-Reject Wait-Conn-Ack/
3064 Elect
3065 Timeout Error Closed
3067 Wait-Returns Win-Election I-Disc,R-Snd-CEA R-Open
3068 I-Peer-Disc I-Disc, R-Open
3069 R-Snd-CEA
3070 I-Rcv-CEA R-Disc I-Open
3071 R-Peer-Disc R-Disc Wait-I-CEA
3072 R-Conn-CER R-Reject Wait-Returns
3073 Timeout Error Closed
3075 R-Open Send-Message R-Snd-Message R-Open
3076 R-Rcv-Message Process R-Open
3077 R-Rcv-DWR Process-DWR, R-Open
3078 R-Snd-DWA
3079 R-Rcv-DWA Process-DWA R-Open
3080 R-Conn-CER R-Reject R-Open
3081 Stop R-Snd-DPR Closing
3082 R-Rcv-DPR R-Snd-DPA, Closed
3083 R-Disc
3085 R-Peer-Disc R-Disc Closed
3086 R-Rcv-CER R-Snd-CEA R-Open
3087 R-Rcv-CEA Process-CEA R-Open
3089 I-Open Send-Message I-Snd-Message I-Open
3090 I-Rcv-Message Process I-Open
3091 I-Rcv-DWR Process-DWR, I-Open
3092 I-Snd-DWA
3093 I-Rcv-DWA Process-DWA I-Open
3094 R-Conn-CER R-Reject I-Open
3095 Stop I-Snd-DPR Closing
3096 I-Rcv-DPR I-Snd-DPA, Closed
3097 I-Disc
3098 I-Peer-Disc I-Disc Closed
3099 I-Rcv-CER I-Snd-CEA I-Open
3100 I-Rcv-CEA Process-CEA I-Open
3102 Closing I-Rcv-DPA I-Disc Closed
3103 R-Rcv-DPA R-Disc Closed
3104 Timeout Error Closed
3105 I-Peer-Disc I-Disc Closed
3106 R-Peer-Disc R-Disc Closed
3108 5.6.1. Incoming connections
3110 When a connection request is received from a Diameter peer, it is
3111 not, in the general case, possible to know the identity of that peer
3112 until a CER is received from it. This is because host and port
3113 determine the identity of a Diameter peer; and the source port of an
3114 incoming connection is arbitrary. Upon receipt of CER, the identity
3115 of the connecting peer can be uniquely determined from Origin-Host.
3117 For this reason, a Diameter peer must employ logic separate from the
3118 state machine to receive connection requests, accept them, and await
3119 CER. Once CER arrives on a new connection, the Origin-Host that
3120 identifies the peer is used to locate the state machine associated
3121 with that peer, and the new connection and CER are passed to the
3122 state machine as an R-Conn-CER event.
3124 The logic that handles incoming connections SHOULD close and discard
3125 the connection if any message other than CER arrives, or if an
3126 implementation-defined timeout occurs prior to receipt of CER.
3128 Because handling of incoming connections up to and including receipt
3129 of CER requires logic, separate from that of any individual state
3130 machine associated with a particular peer, it is described separately
3131 in this section rather than in the state machine above.
3133 5.6.2. Events
3135 Transitions and actions in the automaton are caused by events. In
3136 this section, we will ignore the -I and -R prefix, since the actual
3137 event would be identical, but would occur on one of two possible
3138 connections.
3140 Start The Diameter application has signaled that a
3141 connection should be initiated with the peer.
3143 R-Conn-CER An acknowledgement is received stating that the
3144 transport connection has been established, and the
3145 associated CER has arrived.
3147 Rcv-Conn-Ack A positive acknowledgement is received confirming that
3148 the transport connection is established.
3150 Rcv-Conn-Nack A negative acknowledgement was received stating that
3151 the transport connection was not established.
3153 Timeout An application-defined timer has expired while waiting
3154 for some event.
3156 Rcv-CER A CER message from the peer was received.
3158 Rcv-CEA A CEA message from the peer was received.
3160 Rcv-Non-CEA A message other than CEA from the peer was received.
3162 Peer-Disc A disconnection indication from the peer was received.
3164 Rcv-DPR A DPR message from the peer was received.
3166 Rcv-DPA A DPA message from the peer was received.
3168 Win-Election An election was held, and the local node was the
3169 winner.
3171 Send-Message A message is to be sent.
3173 Rcv-Message A message other than CER, CEA, DPR, DPA, DWR or DWA
3174 was received.
3176 Stop The Diameter application has signaled that a
3177 connection should be terminated (e.g., on system
3178 shutdown).
3180 5.6.3. Actions
3182 Actions in the automaton are caused by events and typically indicate
3183 the transmission of packets and/or an action to be taken on the
3184 connection. In this section we will ignore the I- and R-prefix,
3185 since the actual action would be identical, but would occur on one of
3186 two possible connections.
3188 Snd-Conn-Req A transport connection is initiated with the peer.
3190 Accept The incoming connection associated with the R-Conn-CER
3191 is accepted as the responder connection.
3193 Reject The incoming connection associated with the R-Conn-CER
3194 is disconnected.
3196 Process-CER The CER associated with the R-Conn-CER is processed.
3197 Snd-CER A CER message is sent to the peer.
3199 Snd-CEA A CEA message is sent to the peer.
3201 Cleanup If necessary, the connection is shutdown, and any
3202 local resources are freed.
3204 Error The transport layer connection is disconnected, either
3205 politely or abortively, in response to an error
3206 condition. Local resources are freed.
3208 Process-CEA A received CEA is processed.
3210 Snd-DPR A DPR message is sent to the peer.
3212 Snd-DPA A DPA message is sent to the peer.
3214 Disc The transport layer connection is disconnected, and
3215 local resources are freed.
3217 Elect An election occurs (see Section 5.6.4 for more
3218 information).
3220 Snd-Message A message is sent.
3222 Snd-DWR A DWR message is sent.
3224 Snd-DWA A DWA message is sent.
3226 Process-DWR The DWR message is serviced.
3228 Process-DWA The DWA message is serviced.
3230 Process A message is serviced.
3232 5.6.4. The Election Process
3234 The election is performed on the responder. The responder compares
3235 the Origin-Host received in the CER with its own Origin-Host as two
3236 streams of octets. If the local Origin-Host lexicographically
3237 succeeds the received Origin-Host a Win-Election event is issued
3238 locally.
3240 To be consistent with DNS case insensitivity, octets that fall in the
3241 ASCII range 'a' through 'z' MUST compare equally to their upper-case
3242 counterparts between 'A' and 'Z', i.e. value 0x41 compares equal to
3243 0x61, 0x42 to 0x62 and so forth up to and including 0x5a and 0x7a.
3245 The winner of the election MUST close the connection it initiated.
3246 Historically, maintaining the responder side of a connection was more
3247 efficient than maintaining the initiator side. However, current
3248 practices makes this distinction irrelevant.
3250 5.6.5. Capabilities Update
3252 A Diameter node MUST initiate peer capabilities update by sending a
3253 Capabilities-Exchange-Req (CER) to all its peers which supports peer
3254 capabilities update and is in OPEN state. The receiver of CER in
3255 open state MUST process and reply to the CER as a described in
3256 Section 5.3. The CEA which the receiver sends MUST contain its
3257 latest capabilities. Note that peers which successfully process the
3258 peer capabilities update SHOULD also update their routing tables to
3259 reflect the change. The receiver of the CEA, with a Result-Code AVP
3260 other than DIAMETER_SUCCESS, initiates the transport disconnect. The
3261 peer may periodically attempt to reconnect, as stated in Section 2.1.
3263 Peer capabilities update in the open state SHOULD be limited to the
3264 advertisement of the new list of supported applications and MUST
3265 preclude re-negotiation of security mechanism or other capabilities.
3266 If any capabilities change happens in the node (e.g. change in
3267 security mechanisms), other than a change in the supported
3268 applications, the node SHOULD gracefully terminate (setting the
3269 Disconnect-Cause AVP value to REBOOTING) and re-establish the
3270 diameter connections to all the peers.
3272 6. Diameter message processing
3274 This section describes how Diameter requests and answers are created
3275 and processed.
3277 6.1. Diameter Request Routing Overview
3279 A request is sent towards its final destination using a combination
3280 of the Destination-Realm and Destination-Host AVPs, in one of these
3281 three combinations:
3283 o a request that is not able to be proxied (such as CER) MUST NOT
3284 contain either Destination-Realm or Destination-Host AVPs.
3286 o a request that needs to be sent to a home server serving a
3287 specific realm, but not to a specific server (such as the first
3288 request of a series of round-trips), MUST contain a Destination-
3289 Realm AVP, but MUST NOT contain a Destination-Host AVP.
3291 o otherwise, a request that needs to be sent to a specific home
3292 server among those serving a given realm, MUST contain both the
3293 Destination-Realm and Destination-Host AVPs.
3295 The Destination-Host AVP is used as described above when the
3296 destination of the request is fixed, which includes:
3298 o Authentication requests that span multiple round trips
3300 o A Diameter message that uses a security mechanism that makes use
3301 of a pre-established session key shared between the source and the
3302 final destination of the message.
3304 o Server initiated messages that MUST be received by a specific
3305 Diameter client (e.g., access device), such as the Abort-Session-
3306 Request message, which is used to request that a particular user's
3307 session be terminated.
3309 Note that an agent can forward a request to a host described in the
3310 Destination-Host AVP only if the host in question is included in its
3311 peer table (see Section 2.7). Otherwise, the request is routed based
3312 on the Destination-Realm only (see Sections 6.1.6).
3314 The Destination-Realm AVP MUST be present if the message is
3315 proxiable. Request messages that may be forwarded by Diameter agents
3316 (proxies, redirects or relays) MUST also contain an Acct-
3317 Application-Id AVP, an Auth-Application-Id AVP or a Vendor-Specific-
3318 Application-Id AVP. A message that MUST NOT be forwarded by Diameter
3319 agents (proxies, redirects or relays) MUST not include the
3320 Destination-Realm in its ABNF. The value of the Destination-Realm
3321 AVP MAY be extracted from the User-Name AVP, or other application-
3322 specific methods.
3324 When a message is received, the message is processed in the following
3325 order:
3327 o If the message is destined for the local host, the procedures
3328 listed in Section 6.1.4 are followed.
3330 o If the message is intended for a Diameter peer with whom the local
3331 host is able to directly communicate, the procedures listed in
3332 Section 6.1.5 are followed. This is known as Request Forwarding.
3334 o The procedures listed in Section 6.1.6 are followed, which is
3335 known as Request Routing.
3337 o If none of the above is successful, an answer is returned with the
3338 Result-Code set to DIAMETER_UNABLE_TO_DELIVER, with the E-bit set.
3340 For routing of Diameter messages to work within an administrative
3341 domain, all Diameter nodes within the realm MUST be peers.
3343 Note the processing rules contained in this section are intended to
3344 be used as general guidelines to Diameter developers. Certain
3345 implementations MAY use different methods than the ones described
3346 here, and still comply with the protocol specification. See Section
3347 7 for more detail on error handling.
3349 6.1.1. Originating a Request
3351 When creating a request, in addition to any other procedures
3352 described in the application definition for that specific request,
3353 the following procedures MUST be followed:
3355 o the Command-Code is set to the appropriate value
3357 o the 'R' bit is set
3359 o the End-to-End Identifier is set to a locally unique value
3361 o the Origin-Host and Origin-Realm AVPs MUST be set to the
3362 appropriate values, used to identify the source of the message
3364 o the Destination-Host and Destination-Realm AVPs MUST be set to the
3365 appropriate values as described in Section 6.1.
3367 o an Acct-Application-Id AVP, an Auth-Application-Id or a Vendor-
3368 Specific-Application-Id AVP must be included if the request is
3369 proxiable. The application id present in one of these relevant
3370 AVPs must match the application id present in the diameter message
3371 header.
3373 6.1.2. Sending a Request
3375 When sending a request, originated either locally, or as the result
3376 of a forwarding or routing operation, the following procedures MUST
3377 be followed:
3379 o the Hop-by-Hop Identifier should be set to a locally unique value.
3381 o The message should be saved in the list of pending requests.
3383 Other actions to perform on the message based on the particular role
3384 the agent is playing are described in the following sections.
3386 6.1.3. Receiving Requests
3388 A relay or proxy agent MUST check for forwarding loops when receiving
3389 requests. A loop is detected if the server finds its own identity in
3390 a Route-Record AVP. When such an event occurs, the agent MUST answer
3391 with the Result-Code AVP set to DIAMETER_LOOP_DETECTED.
3393 6.1.4. Processing Local Requests
3395 A request is known to be for local consumption when one of the
3396 following conditions occur:
3398 o The Destination-Host AVP contains the local host's identity,
3400 o The Destination-Host AVP is not present, the Destination-Realm AVP
3401 contains a realm the server is configured to process locally, and
3402 the Diameter application is locally supported, or
3404 o Both the Destination-Host and the Destination-Realm are not
3405 present.
3407 When a request is locally processed, the rules in Section 6.2 should
3408 be used to generate the corresponding answer.
3410 6.1.5. Request Forwarding
3412 Request forwarding is done using the Diameter Peer Table. The
3413 Diameter peer table contains all of the peers that the local node is
3414 able to directly communicate with.
3416 When a request is received, and the host encoded in the Destination-
3417 Host AVP is one that is present in the peer table, the message SHOULD
3418 be forwarded to the peer.
3420 6.1.6. Request Routing
3422 Diameter request message routing is done via realms and applications.
3423 A Diameter message that may be forwarded by Diameter agents (proxies,
3424 redirects or relays) MUST include the target realm in the
3425 Destination-Realm AVP. Request routing SHOULD rely on the
3426 Destination-Realm AVP and the application id present in the request
3427 message header to aid in the routing decision. It MAY also rely on
3428 the application identification AVPs Auth-Application-Id, Acct-
3429 Application-Id or Vendor-Specific-Application-Id instead of the
3430 application id in the message header as a secondary measure. The
3431 realm MAY be retrieved from the User-Name AVP, which is in the form
3432 of a Network Access Identifier (NAI). The realm portion of the NAI
3433 is inserted in the Destination-Realm AVP.
3435 Diameter agents MAY have a list of locally supported realms and
3436 applications, and MAY have a list of externally supported realms and
3437 applications. When a request is received that includes a realm
3438 and/or application that is not locally supported, the message is
3439 routed to the peer configured in the Routing Table (see Section 2.7).
3441 Realm names and application identifiers are the minimum supported
3442 routing criteria, additional routing information maybe needed to
3443 support redirect semantics.
3445 6.1.7. Predictive Loop Avoidance
3447 Before forwarding or routing a request, Diameter agents, in addition
3448 to processing done in Section 6.1.3, SHOULD check for the presence of
3449 candidate route's peer identity in any of the Route-Record AVPs. In
3450 an event of the agent detecting the presence of a candidate route's
3451 peer identity in a Route-Record AVP, the agent MUST ignore such route
3452 for the Diameter request message and attempt alternate routes if any.
3453 In case all the candidate routes are eliminated by the above
3454 criteria, the agent SHOULD return DIAMETER_UNABLE_TO_DELIVER message.
3456 6.1.8. Redirecting requests
3458 When a redirect agent receives a request whose routing entry is set
3459 to REDIRECT, it MUST reply with an answer message with the 'E' bit
3460 set, while maintaining the Hop-by-Hop Identifier in the header, and
3461 include the Result-Code AVP to DIAMETER_REDIRECT_INDICATION. Each of
3462 the servers associated with the routing entry are added in separate
3463 Redirect-Host AVP.
3465 +------------------+
3466 | Diameter |
3467 | Redirect Agent |
3468 +------------------+
3469 ^ | 2. command + 'E' bit
3470 1. Request | | Result-Code =
3471 joe@example.com | | DIAMETER_REDIRECT_INDICATION +
3472 | | Redirect-Host AVP(s)
3473 | v
3474 +-------------+ 3. Request +-------------+
3475 | example.com |------------->| example.net |
3476 | Relay | | Diameter |
3477 | Agent |<-------------| Server |
3478 +-------------+ 4. Answer +-------------+
3480 Figure 5: Diameter Redirect Agent
3482 The receiver of the answer message with the 'E' bit set, and the
3483 Result-Code AVP set to DIAMETER_REDIRECT_INDICATION uses the hop-by-
3484 hop field in the Diameter header to identify the request in the
3485 pending message queue (see Section 5.3) that is to be redirected. If
3486 no transport connection exists with the new agent, one is created,
3487 and the request is sent directly to it.
3489 Multiple Redirect-Host AVPs are allowed. The receiver of the answer
3490 message with the 'E' bit set selects exactly one of these hosts as
3491 the destination of the redirected message.
3493 When the Redirect-Host-Usage AVP included in the answer message has a
3494 non-zero value, a route entry for the redirect indications is created
3495 and cached by the receiver. The redirect usage for such route entry
3496 is set by the value of Redirect-Host-Usage AVP and the lifetime of
3497 the cached route entry is set by Redirect-Max-Cache-Time AVP value.
3499 It is possible that multiple redirect indications can create multiple
3500 cached route entries differing only in their redirect usage and the
3501 peer to forward messages to. As an example, two(2) route entries
3502 that are created by two(2) redirect indications results in two(2)
3503 cached routes for the same realm and application Id. However, one
3504 has a redirect usage of ALL_SESSION where matching request will be
3505 forwarded to one peer and the other has a redirect usage of ALL_REALM
3506 where request are forwarded to another peer. Therefore, an incoming
3507 request that matches the realm and application Id of both routes will
3508 need additional resolution. In such a case, a routing precedence
3509 rule MUST be used againts the redirect usage value to resolve the
3510 contention. The precedence rule can be found in Section 6.13.
3512 6.1.9. Relaying and Proxying Requests
3514 A relay or proxy agent MUST append a Route-Record AVP to all requests
3515 forwarded. The AVP contains the identity of the peer the request was
3516 received from.
3518 The Hop-by-Hop identifier in the request is saved, and replaced with
3519 a locally unique value. The source of the request is also saved,
3520 which includes the IP address, port and protocol.
3522 A relay or proxy agent MAY include the Proxy-Info AVP in requests if
3523 it requires access to any local state information when the
3524 corresponding response is received. Proxy-Info AVP has certain
3525 security implications and SHOULD contain an embedded HMAC with a
3526 node-local key. Alternatively, it MAY simply use local storage to
3527 store state information.
3529 The message is then forwarded to the next hop, as identified in the
3530 Routing Table.
3532 Figure 6 provides an example of message routing using the procedures
3533 listed in these sections.
3535 (Origin-Host=nas.mno.net) (Origin-Host=nas.mno.net)
3536 (Origin-Realm=mno.net) (Origin-Realm=mno.net)
3537 (Destination-Realm=example.com) (Destination-
3538 Realm=example.com)
3539 (Route-Record=nas.example.net)
3540 +------+ ------> +------+ ------> +------+
3541 | | (Request) | | (Request) | |
3542 | NAS +-------------------+ DRL +-------------------+ HMS |
3543 | | | | | |
3544 +------+ <------ +------+ <------ +------+
3545 example.net (Answer) example.net (Answer) example.com
3546 (Origin-Host=hms.example.com) (Origin-Host=hms.example.com)
3547 (Origin-Realm=example.com) (Origin-Realm=example.com)
3549 Figure 6: Routing of Diameter messages
3551 Relay agents do not require full validation of incoming messages. At
3552 a minimum, validation of the message header and relevant routing AVPs
3553 has to be done when relaying messages.
3555 6.2. Diameter Answer Processing
3557 When a request is locally processed, the following procedures MUST be
3558 applied to create the associated answer, in addition to any
3559 additional procedures that MAY be discussed in the Diameter
3560 application defining the command:
3562 o The same Hop-by-Hop identifier in the request is used in the
3563 answer.
3565 o The local host's identity is encoded in the Origin-Host AVP.
3567 o The Destination-Host and Destination-Realm AVPs MUST NOT be
3568 present in the answer message.
3570 o The Result-Code AVP is added with its value indicating success or
3571 failure.
3573 o If the Session-Id is present in the request, it MUST be included
3574 in the answer.
3576 o Any Proxy-Info AVPs in the request MUST be added to the answer
3577 message, in the same order they were present in the request.
3579 o The 'P' bit is set to the same value as the one in the request.
3581 o The same End-to-End identifier in the request is used in the
3582 answer.
3584 Note that the error messages (see Section 7.3) are also subjected to
3585 the above processing rules.
3587 6.2.1. Processing received Answers
3589 A Diameter client or proxy MUST match the Hop-by-Hop Identifier in an
3590 answer received against the list of pending requests. The
3591 corresponding message should be removed from the list of pending
3592 requests. It SHOULD ignore answers received that do not match a
3593 known Hop-by-Hop Identifier.
3595 6.2.2. Relaying and Proxying Answers
3597 If the answer is for a request which was proxied or relayed, the
3598 agent MUST restore the original value of the Diameter header's Hop-
3599 by-Hop Identifier field.
3601 If the last Proxy-Info AVP in the message is targeted to the local
3602 Diameter server, the AVP MUST be removed before the answer is
3603 forwarded.
3605 If a relay or proxy agent receives an answer with a Result-Code AVP
3606 indicating a failure, it MUST NOT modify the contents of the AVP.
3607 Any additional local errors detected SHOULD be logged, but not
3608 reflected in the Result-Code AVP. If the agent receives an answer
3609 message with a Result-Code AVP indicating success, and it wishes to
3610 modify the AVP to indicate an error, it MUST modify the Result-Code
3611 AVP to contain the appropriate error in the message destined towards
3612 the access device as well as include the Error-Reporting-Host AVP and
3613 it MUST issue an STR on behalf of the access device.
3615 The agent MUST then send the answer to the host that it received the
3616 original request from.
3618 6.3. Origin-Host AVP
3620 The Origin-Host AVP (AVP Code 264) is of type DiameterIdentity, and
3621 MUST be present in all Diameter messages. This AVP identifies the
3622 endpoint that originated the Diameter message. Relay agents MUST NOT
3623 modify this AVP.
3625 The value of the Origin-Host AVP is guaranteed to be unique within a
3626 single host.
3628 Note that the Origin-Host AVP may resolve to more than one address as
3629 the Diameter peer may support more than one address.
3631 This AVP SHOULD be placed as close to the Diameter header as
3632 possible. 6.10
3634 6.4. Origin-Realm AVP
3636 The Origin-Realm AVP (AVP Code 296) is of type DiameterIdentity.
3637 This AVP contains the Realm of the originator of any Diameter message
3638 and MUST be present in all messages.
3640 This AVP SHOULD be placed as close to the Diameter header as
3641 possible.
3643 6.5. Destination-Host AVP
3645 The Destination-Host AVP (AVP Code 293) is of type DiameterIdentity.
3646 This AVP MUST be present in all unsolicited agent initiated messages,
3647 MAY be present in request messages, and MUST NOT be present in Answer
3648 messages.
3650 The absence of the Destination-Host AVP will cause a message to be
3651 sent to any Diameter server supporting the application within the
3652 realm specified in Destination-Realm AVP.
3654 This AVP SHOULD be placed as close to the Diameter header as
3655 possible.
3657 6.6. Destination-Realm AVP
3659 The Destination-Realm AVP (AVP Code 283) is of type DiameterIdentity,
3660 and contains the realm the message is to be routed to. The
3661 Destination-Realm AVP MUST NOT be present in Answer messages.
3662 Diameter Clients insert the realm portion of the User-Name AVP.
3663 Diameter servers initiating a request message use the value of the
3664 Origin-Realm AVP from a previous message received from the intended
3665 target host (unless it is known a priori). When present, the
3666 Destination-Realm AVP is used to perform message routing decisions.
3668 Request messages whose ABNF does not list the Destination-Realm AVP
3669 as a mandatory AVP are inherently non-routable messages.
3671 This AVP SHOULD be placed as close to the Diameter header as
3672 possible.
3674 6.7. Routing AVPs
3676 The AVPs defined in this section are Diameter AVPs used for routing
3677 purposes. These AVPs change as Diameter messages are processed by
3678 agents.
3680 6.7.1. Route-Record AVP
3682 The Route-Record AVP (AVP Code 282) is of type DiameterIdentity. The
3683 identity added in this AVP MUST be the same as the one received in
3684 the Origin-Host of the Capabilities Exchange message.
3686 6.7.2. Proxy-Info AVP
3688 The Proxy-Info AVP (AVP Code 284) is of type Grouped. The Grouped
3689 Data field has the following ABNF grammar:
3691 Proxy-Info ::= < AVP Header: 284 >
3692 { Proxy-Host }
3693 { Proxy-State }
3694 * [ AVP ]
3696 6.7.3. Proxy-Host AVP
3698 The Proxy-Host AVP (AVP Code 280) is of type DiameterIdentity. This
3699 AVP contains the identity of the host that added the Proxy-Info AVP.
3701 6.7.4. Proxy-State AVP
3703 The Proxy-State AVP (AVP Code 33) is of type OctetString, and
3704 contains state local information, and MUST be treated as opaque data.
3706 6.8. Auth-Application-Id AVP
3708 The Auth-Application-Id AVP (AVP Code 258) is of type Unsigned32 and
3709 is used in order to advertise support of the Authentication and
3710 Authorization portion of an application (see Section 2.4). The Auth-
3711 Application-Id MUST also be present in all Authentication and/or
3712 Authorization messages that are defined in a separate Diameter
3713 specification and have an Application ID assigned. If present in a
3714 message, the value of the Auth-Application-Id AVP MUST match the
3715 application id present in the diameter message header except when
3716 used in a CER or CEA messages.
3718 6.9. Acct-Application-Id AVP
3720 The Acct-Application-Id AVP (AVP Code 259) is of type Unsigned32 and
3721 is used in order to advertise support of the Accounting portion of an
3722 application (see Section 2.4). The Acct-Application-Id MUST also be
3723 present in all Accounting messages. Exactly one of the Auth-
3724 Application-Id and Acct-Application-Id AVPs MAY be present. If
3725 present in a message, the value of the Acct-Application-Id AVP MUST
3726 match the application id present in the diameter message header
3727 except when used in a CER or CEA messages.
3729 6.10. Inband-Security-Id AVP
3731 The Inband-Security-Id AVP (AVP Code 299) is of type Unsigned32 and
3732 is used in order to advertise support of the Security portion of the
3733 application.
3735 Currently, the following values are supported, but there is ample
3736 room to add new security Ids.
3738 NO_INBAND_SECURITY 0
3740 This peer does not support TLS. This is the default value, if the
3741 AVP is omitted.
3743 TLS 1
3745 This node supports TLS security, as defined by [RFC4346].
3747 6.11. Vendor-Specific-Application-Id AVP
3749 The Vendor-Specific-Application-Id AVP (AVP Code 260) is of type
3750 Grouped and is used to advertise support of a vendor-specific
3751 Diameter Application. Exactly one instance of either Auth-
3752 Application-Id or Acct-Application-Id AVP MAY be present. The
3753 application identifier carried by either Auth-Application-Id or Acct-
3754 Application-Id AVP MUST comply with vendor specific application
3755 identifier assignment described in Sec 11.3. It MUST also match the
3756 application id present in the diameter header except when used in a
3757 CER or CEA messages.
3759 The Vendor-Id AVP is an informational AVP pertaining to the vendor
3760 who may have authorship of the vendor-specific Diameter application.
3761 It MUST NOT be used as a means of defining a completely separate
3762 vendor-specific application identifier space.
3764 This AVP MUST also be present as the first AVP in all experimental
3765 commands defined in the vendor-specific application.
3767 This AVP SHOULD be placed as close to the Diameter header as
3768 possible.
3770 AVP Format
3772 ::= < AVP Header: 260 >
3773 { Vendor-Id }
3774 ({ Auth-Application-Id } /
3775 { Acct-Application-Id })
3777 6.12. Redirect-Host AVP
3779 One or more of instances of this AVP MUST be present if the answer
3780 message's 'E' bit is set and the Result-Code AVP is set to
3781 DIAMETER_REDIRECT_INDICATION.
3783 Upon receiving the above, the receiving Diameter node SHOULD forward
3784 the request directly to one of the hosts identified in these AVPs.
3785 The server contained in the selected Redirect-Host AVP SHOULD be used
3786 for all messages pertaining to this session.
3788 6.13. Redirect-Host-Usage AVP
3790 The Redirect-Host-Usage AVP (AVP Code 261) is of type Enumerated.
3791 This AVP MAY be present in answer messages whose 'E' bit is set and
3792 the Result-Code AVP is set to DIAMETER_REDIRECT_INDICATION.
3794 When present, this AVP dictates how the routing entry resulting from
3795 the Redirect-Host is to be used. The following values are supported:
3797 DONT_CACHE 0
3799 The host specified in the Redirect-Host AVP should not be cached.
3800 This is the default value.
3802 ALL_SESSION 1
3804 All messages within the same session, as defined by the same value
3805 of the Session-ID AVP MAY be sent to the host specified in the
3806 Redirect-Host AVP.
3808 ALL_REALM 2
3810 All messages destined for the realm requested MAY be sent to the
3811 host specified in the Redirect-Host AVP.
3813 REALM_AND_APPLICATION 3
3815 All messages for the application requested to the realm specified
3816 MAY be sent to the host specified in the Redirect-Host AVP.
3818 ALL_APPLICATION 4
3820 All messages for the application requested MAY be sent to the host
3821 specified in the Redirect-Host AVP.
3823 ALL_HOST 5
3825 All messages that would be sent to the host that generated the
3826 Redirect-Host MAY be sent to the host specified in the Redirect-
3827 Host AVP.
3829 ALL_USER 6
3831 All messages for the user requested MAY be sent to the host
3832 specified in the Redirect-Host AVP.
3834 When multiple cached routes are created by redirect indications and
3835 they differs only in redirect usage and peers to forward requests to
3836 (see Section 6.1.8), a precedence rule MUST be applied to the
3837 redirect usage values of the cached routes during normal routing to
3838 resolve contentions that may occur. The precedence rule is the order
3839 that dictate which redirect usage should be considered before any
3840 other as they appear. The order is as follows:
3842 1. ALL_SESSION
3844 2. ALL_USER
3846 3. REALM_AND_APPLICATION
3848 4. ALL_REALM
3850 5. ALL_APPLICATION
3852 6. ALL_HOST
3854 6.14. Redirect-Max-Cache-Time AVP
3856 The Redirect-Max-Cache-Time AVP (AVP Code 262) is of type Unsigned32.
3857 This AVP MUST be present in answer messages whose 'E' bit is set, the
3858 Result-Code AVP is set to DIAMETER_REDIRECT_INDICATION and the
3859 Redirect-Host-Usage AVP set to a non-zero value.
3861 This AVP contains the maximum number of seconds the peer and route
3862 table entries, created as a result of the Redirect-Host, will be
3863 cached. Note that once a host created due to a redirect indication
3864 is no longer reachable, any associated peer and routing table entries
3865 MUST be deleted.
3867 6.15. E2E-Sequence AVP
3869 The E2E-Sequence AVP (AVP Code 300) provides anti-replay protection
3870 for end to end messages and is of type grouped. It contains a random
3871 value (an OctetString with a nonce) and counter (an Integer). For
3872 each end-to-end peer with which a node communicates (or remembers
3873 communicating) a different nonce value MUST be used and the counter
3874 is initiated at zero and increases by one each time this AVP is
3875 emitted to that peer.
3877 7. Error Handling
3879 There are two different types of errors in Diameter; protocol and
3880 application errors. A protocol error is one that occurs at the base
3881 protocol level, and MAY require per hop attention (e.g., message
3882 routing error). Application errors, on the other hand, generally
3883 occur due to a problem with a function specified in a Diameter
3884 application (e.g., user authentication, Missing AVP).
3886 Result-Code AVP values that are used to report protocol errors MUST
3887 only be present in answer messages whose 'E' bit is set. When a
3888 request message is received that causes a protocol error, an answer
3889 message is returned with the 'E' bit set, and the Result-Code AVP is
3890 set to the appropriate protocol error value. As the answer is sent
3891 back towards the originator of the request, each proxy or relay agent
3892 MAY take action on the message.
3894 1. Request +---------+ Link Broken
3895 +-------------------------->|Diameter |----///----+
3896 | +---------------------| | v
3897 +------+--+ | 2. answer + 'E' set | Relay 2 | +--------+
3898 |Diameter |<-+ (Unable to Forward) +---------+ |Diameter|
3899 | | | Home |
3900 | Relay 1 |--+ +---------+ | Server |
3901 +---------+ | 3. Request |Diameter | +--------+
3902 +-------------------->| | ^
3903 | Relay 3 |-----------+
3904 +---------+
3906 Figure 7: Example of Protocol Error causing answer message
3908 Figure 7 provides an example of a message forwarded upstream by a
3909 Diameter relay. When the message is received by Relay 2, and it
3910 detects that it cannot forward the request to the home server, an
3911 answer message is returned with the 'E' bit set and the Result-Code
3912 AVP set to DIAMETER_UNABLE_TO_DELIVER. Given that this error falls
3913 within the protocol error category, Relay 1 would take special
3914 action, and given the error, attempt to route the message through its
3915 alternate Relay 3.
3917 +---------+ 1. Request +---------+ 2. Request +---------+
3918 | Access |------------>|Diameter |------------>|Diameter |
3919 | | | | | Home |
3920 | Device |<------------| Relay |<------------| Server |
3921 +---------+ 4. Answer +---------+ 3. Answer +---------+
3922 (Missing AVP) (Missing AVP)
3924 Figure 8: Example of Application Error Answer message
3926 Figure 8 provides an example of a Diameter message that caused an
3927 application error. When application errors occur, the Diameter
3928 entity reporting the error clears the 'R' bit in the Command Flags,
3929 and adds the Result-Code AVP with the proper value. Application
3930 errors do not require any proxy or relay agent involvement, and
3931 therefore the message would be forwarded back to the originator of
3932 the request.
3934 There are certain Result-Code AVP application errors that require
3935 additional AVPs to be present in the answer. In these cases, the
3936 Diameter node that sets the Result-Code AVP to indicate the error
3937 MUST add the AVPs. Examples are:
3939 o An unrecognized AVP is received with the 'M' bit (Mandatory bit)
3940 set, causes an answer to be sent with the Result-Code AVP set to
3941 DIAMETER_AVP_UNSUPPORTED, and the Failed-AVP AVP containing the
3942 offending AVP.
3944 o An AVP that is received with an unrecognized value causes an
3945 answer to be returned with the Result-Code AVP set to
3946 DIAMETER_INVALID_AVP_VALUE, with the Failed-AVP AVP containing the
3947 AVP causing the error.
3949 o A command is received with an AVP that is omitted, yet is
3950 mandatory according to the command's ABNF. The receiver issues an
3951 answer with the Result-Code set to DIAMETER_MISSING_AVP, and
3952 creates an AVP with the AVP Code and other fields set as expected
3953 in the missing AVP. The created AVP is then added to the Failed-
3954 AVP AVP.
3956 The Result-Code AVP describes the error that the Diameter node
3957 encountered in its processing. In case there are multiple errors,
3958 the Diameter node MUST report only the first error it encountered
3959 (detected possibly in some implementation dependent order). The
3960 specific errors that can be described by this AVP are described in
3961 the following section.
3963 7.1. Result-Code AVP
3965 The Result-Code AVP (AVP Code 268) is of type Unsigned32 and
3966 indicates whether a particular request was completed successfully or
3967 whether an error occurred. All Diameter answer messages defined in
3968 IETF applications MUST include one Result-Code AVP. A non-successful
3969 Result-Code AVP (one containing a non 2xxx value other than
3970 DIAMETER_REDIRECT_INDICATION) MUST include the Error-Reporting-Host
3971 AVP if the host setting the Result-Code AVP is different from the
3972 identity encoded in the Origin-Host AVP.
3974 The Result-Code data field contains an IANA-managed 32-bit address
3975 space representing errors (see Section 11.4). Diameter provides the
3976 following classes of errors, all identified by the thousands digit in
3977 the decimal notation:
3979 o 1xxx (Informational)
3981 o 2xxx (Success)
3983 o 3xxx (Protocol Errors)
3985 o 4xxx (Transient Failures)
3987 o 5xxx (Permanent Failure)
3989 A non-recognized class (one whose first digit is not defined in this
3990 section) MUST be handled as a permanent failure.
3992 7.1.1. Informational
3994 Errors that fall within this category are used to inform the
3995 requester that a request could not be satisfied, and additional
3996 action is required on its part before access is granted.
3998 DIAMETER_MULTI_ROUND_AUTH 1001
4000 This informational error is returned by a Diameter server to
4001 inform the access device that the authentication mechanism being
4002 used requires multiple round trips, and a subsequent request needs
4003 to be issued in order for access to be granted.
4005 7.1.2. Success
4007 Errors that fall within the Success category are used to inform a
4008 peer that a request has been successfully completed.
4010 DIAMETER_SUCCESS 2001
4012 The Request was successfully completed.
4014 DIAMETER_LIMITED_SUCCESS 2002
4016 When returned, the request was successfully completed, but
4017 additional processing is required by the application in order to
4018 provide service to the user.
4020 7.1.3. Protocol Errors
4022 Errors that fall within the Protocol Error category SHOULD be treated
4023 on a per-hop basis, and Diameter proxies MAY attempt to correct the
4024 error, if it is possible. Note that these and only these errors MUST
4025 only be used in answer messages whose 'E' bit is set. To provide
4026 backward compatibility with existing implementations that follow
4027 [RFC3588], some of the error values that have previously been used in
4028 this category by [RFC3588] will not be re-used. Therefore the error
4029 values enumerated here maybe non-sequential.
4031 DIAMETER_UNABLE_TO_DELIVER 3002
4033 This error is given when Diameter can not deliver the message to
4034 the destination, either because no host within the realm
4035 supporting the required application was available to process the
4036 request, or because Destination-Host AVP was given without the
4037 associated Destination-Realm AVP.
4039 DIAMETER_REALM_NOT_SERVED 3003
4041 The intended realm of the request is not recognized.
4043 DIAMETER_TOO_BUSY 3004
4045 When returned, a Diameter node SHOULD attempt to send the message
4046 to an alternate peer. This error MUST only be used when a
4047 specific server is requested, and it cannot provide the requested
4048 service.
4050 DIAMETER_LOOP_DETECTED 3005
4052 An agent detected a loop while trying to get the message to the
4053 intended recipient. The message MAY be sent to an alternate peer,
4054 if one is available, but the peer reporting the error has
4055 identified a configuration problem.
4057 DIAMETER_REDIRECT_INDICATION 3006
4059 A redirect agent has determined that the request could not be
4060 satisfied locally and the initiator of the request should direct
4061 the request directly to the server, whose contact information has
4062 been added to the response. When set, the Redirect-Host AVP MUST
4063 be present.
4065 DIAMETER_APPLICATION_UNSUPPORTED 3007
4067 A request was sent for an application that is not supported.
4069 DIAMETER_INVALID_BIT_IN_HEADER 3011
4071 This error is returned when a reserved bit in the Diameter header
4072 is set to one (1) or the bits in the Diameter header defined in
4073 Sec 3 are set incorrectly.
4075 DIAMETER_INVALID_MESSAGE_LENGTH 3012
4077 This error is returned when a request is received with an invalid
4078 message length.
4080 7.1.4. Transient Failures
4082 Errors that fall within the transient failures category are used to
4083 inform a peer that the request could not be satisfied at the time it
4084 was received, but MAY be able to satisfy the request in the future.
4085 Note that these errors MUST be used in answer messages whose 'E' bit
4086 is not set.
4088 DIAMETER_AUTHENTICATION_REJECTED 4001
4090 The authentication process for the user failed, most likely due to
4091 an invalid password used by the user. Further attempts MUST only
4092 be tried after prompting the user for a new password.
4094 DIAMETER_OUT_OF_SPACE 4002
4096 A Diameter node received the accounting request but was unable to
4097 commit it to stable storage due to a temporary lack of space.
4099 ELECTION_LOST 4003
4101 The peer has determined that it has lost the election process and
4102 has therefore disconnected the transport connection.
4104 7.1.5. Permanent Failures
4106 Errors that fall within the permanent failures category are used to
4107 inform the peer that the request failed, and should not be attempted
4108 again. Note that these errors SHOULD be used in answer messages
4109 whose 'E' bit is not set. In error conditions where it is not
4110 possible or efficient to compose application specific answer grammar
4111 then answer messages with E-bit set and complying to the grammar
4112 described in 7.2 MAY also be used for permanent errors.
4114 To provide backward compatibility with existing implementations that
4115 follow [RFC3588], some of the error values that have previously been
4116 used in this category by [RFC3588] will not be re-used. Therefore
4117 the error values enumerated here maybe non-sequential.
4119 DIAMETER_AVP_UNSUPPORTED 5001
4121 The peer received a message that contained an AVP that is not
4122 recognized or supported and was marked with the Mandatory bit. A
4123 Diameter message with this error MUST contain one or more Failed-
4124 AVP AVP containing the AVPs that caused the failure.
4126 DIAMETER_UNKNOWN_SESSION_ID 5002
4128 The request contained an unknown Session-Id.
4130 DIAMETER_AUTHORIZATION_REJECTED 5003
4132 A request was received for which the user could not be authorized.
4133 This error could occur if the service requested is not permitted
4134 to the user.
4136 DIAMETER_INVALID_AVP_VALUE 5004
4138 The request contained an AVP with an invalid value in its data
4139 portion. A Diameter message indicating this error MUST include
4140 the offending AVPs within a Failed-AVP AVP.
4142 DIAMETER_MISSING_AVP 5005
4144 The request did not contain an AVP that is required by the Command
4145 Code definition. If this value is sent in the Result-Code AVP, a
4146 Failed-AVP AVP SHOULD be included in the message. The Failed-AVP
4147 AVP MUST contain an example of the missing AVP complete with the
4148 Vendor-Id if applicable. The value field of the missing AVP
4149 should be of correct minimum length and contain zeroes.
4151 DIAMETER_RESOURCES_EXCEEDED 5006
4153 A request was received that cannot be authorized because the user
4154 has already expended allowed resources. An example of this error
4155 condition is a user that is restricted to one dial-up PPP port,
4156 attempts to establish a second PPP connection.
4158 DIAMETER_CONTRADICTING_AVPS 5007
4160 The Home Diameter server has detected AVPs in the request that
4161 contradicted each other, and is not willing to provide service to
4162 the user. The Failed-AVP AVPs MUST be present which contains the
4163 AVPs that contradicted each other.
4165 DIAMETER_AVP_NOT_ALLOWED 5008
4167 A message was received with an AVP that MUST NOT be present. The
4168 Failed-AVP AVP MUST be included and contain a copy of the
4169 offending AVP.
4171 DIAMETER_AVP_OCCURS_TOO_MANY_TIMES 5009
4173 A message was received that included an AVP that appeared more
4174 often than permitted in the message definition. The Failed-AVP
4175 AVP MUST be included and contain a copy of the first instance of
4176 the offending AVP that exceeded the maximum number of occurrences
4178 DIAMETER_NO_COMMON_APPLICATION 5010
4180 This error is returned by a Diameter node that is not acting as a
4181 relay when it receives a CER which advertises a set of
4182 applications that it does not support.
4184 DIAMETER_UNSUPPORTED_VERSION 5011
4186 This error is returned when a request was received, whose version
4187 number is unsupported.
4189 DIAMETER_UNABLE_TO_COMPLY 5012
4191 This error is returned when a request is rejected for unspecified
4192 reasons.
4194 DIAMETER_INVALID_AVP_LENGTH 5014
4196 The request contained an AVP with an invalid length. A Diameter
4197 message indicating this error MUST include the offending AVPs
4198 within a Failed-AVP AVP. In cases where the erroneous avp length
4199 value exceeds the message length or is less than the minimum AVP
4200 header length, it is sufficient to include the offending AVP
4201 header and a zero filled payload of the minimum required length
4202 for the payloads data type. If the AVP is a grouped AVP, the
4203 grouped AVP header with an empty payload would be sufficient to
4204 indicate the offending AVP. In the case where the offending AVP
4205 header cannot be fully decoded when avp length is less than the
4206 minimum AVP header length, it is sufficient to include an
4207 offending AVP header that is formulated by padding the incomplete
4208 AVP header with zero up to the minimum AVP header length.
4210 DIAMETER_NO_COMMON_SECURITY 5017
4212 This error is returned when a CER message is received, and there
4213 are no common security mechanisms supported between the peers. A
4214 Capabilities-Exchange-Answer (CEA) MUST be returned with the
4215 Result-Code AVP set to DIAMETER_NO_COMMON_SECURITY.
4217 DIAMETER_UNKNOWN_PEER 5018
4219 A CER was received from an unknown peer.
4221 DIAMETER_COMMAND_UNSUPPORTED 5019
4223 The Request contained a Command-Code that the receiver did not
4224 recognize or support. This MUST be used when a Diameter node
4225 receives an experimental command that it does not understand.
4227 DIAMETER_INVALID_HDR_BITS 5020
4229 A request was received whose bits in the Diameter header were
4230 either set to an invalid combination, or to a value that is
4231 inconsistent with the command code's definition.
4233 DIAMETER_INVALID_AVP_BITS 5021
4235 A request was received that included an AVP whose flag bits are
4236 set to an unrecognized value, or that is inconsistent with the
4237 AVP's definition.
4239 7.2. Error Bit
4241 The 'E' (Error Bit) in the Diameter header is set when the request
4242 caused a protocol-related error (see Section 7.1.3). A message with
4243 the 'E' bit MUST NOT be sent as a response to an answer message.
4244 Note that a message with the 'E' bit set is still subjected to the
4245 processing rules defined in Section 6.2. When set, the answer
4246 message will not conform to the ABNF specification for the command,
4247 and will instead conform to the following ABNF:
4249 Message Format
4251 ::= < Diameter Header: code, ERR [PXY] >
4252 0*1< Session-Id >
4253 { Origin-Host }
4254 { Origin-Realm }
4255 { Result-Code }
4256 [ Origin-State-Id ]
4257 [ Error-Message ]
4258 [ Error-Reporting-Host ]
4259 [ Failed-AVP ]
4260 * [ Proxy-Info ]
4261 * [ AVP ]
4263 Note that the code used in the header is the same than the one found
4264 in the request message, but with the 'R' bit cleared and the 'E' bit
4265 set. The 'P' bit in the header is set to the same value as the one
4266 found in the request message.
4268 7.3. Error-Message AVP
4270 The Error-Message AVP (AVP Code 281) is of type UTF8String. It MAY
4271 accompany a Result-Code AVP as a human readable error message. The
4272 Error-Message AVP is not intended to be useful in real-time, and
4273 SHOULD NOT be expected to be parsed by network entities.
4275 7.4. Error-Reporting-Host AVP
4277 The Error-Reporting-Host AVP (AVP Code 294) is of type
4278 DiameterIdentity. This AVP contains the identity of the Diameter
4279 host that sent the Result-Code AVP to a value other than 2001
4280 (Success), only if the host setting the Result-Code is different from
4281 the one encoded in the Origin-Host AVP. This AVP is intended to be
4282 used for troubleshooting purposes, and MUST be set when the Result-
4283 Code AVP indicates a failure.
4285 7.5. Failed-AVP AVP
4287 The Failed-AVP AVP (AVP Code 279) is of type Grouped and provides
4288 debugging information in cases where a request is rejected or not
4289 fully processed due to erroneous information in a specific AVP. The
4290 value of the Result-Code AVP will provide information on the reason
4291 for the Failed-AVP AVP. A Diameter message SHOULD contain only one
4292 Failed-AVP that corresponds to the error indicated by the Result-Code
4293 AVP. For practical purposes, this Failed-AVP would typically refer
4294 to the first AVP processing error that a Diameter node encounters.
4296 The possible reasons for this AVP are the presence of an improperly
4297 constructed AVP, an unsupported or unrecognized AVP, an invalid AVP
4298 value, the omission of a required AVP, the presence of an explicitly
4299 excluded AVP (see tables in Section 10), or the presence of two or
4300 more occurrences of an AVP which is restricted to 0, 1, or 0-1
4301 occurrences.
4303 A Diameter message SHOULD contain one Failed-AVP AVP, containing the
4304 entire AVP that could not be processed successfully. If the failure
4305 reason is omission of a required AVP, an AVP with the missing AVP
4306 code, the missing vendor id, and a zero filled payload of the minimum
4307 required length for the omitted AVP will be added. If the failure
4308 reason is an invalid AVP length where the reported length is less
4309 than the minimum AVP header length or greater than the reported
4310 message length, a copy of the offending AVP header and a zero filled
4311 payload of the minimum required length SHOULD be added.
4313 In the case where the offending AVP is embedded within a grouped AVP,
4314 the Failed-AVP MAY contain the grouped AVP which in turn contains the
4315 single offending AVP. The same method MAY be employed if the grouped
4316 AVP itself is embedded in yet another grouped AVP and so on. In this
4317 case, the Failed-AVP MAY contain the grouped AVP heirarchy up to the
4318 single offending AVP. This enables the recipient to detect the
4319 location of the offending AVP when embedded in a group.
4321 AVP Format
4323 ::= < AVP Header: 279 >
4324 1* {AVP}
4326 7.6. Experimental-Result AVP
4328 The Experimental-Result AVP (AVP Code 297) is of type Grouped, and
4329 indicates whether a particular vendor-specific request was completed
4330 successfully or whether an error occurred. Its Data field has the
4331 following ABNF grammar:
4333 AVP Format
4335 Experimental-Result ::= < AVP Header: 297 >
4336 { Vendor-Id }
4337 { Experimental-Result-Code }
4339 The Vendor-Id AVP (see Section 5.3.3) in this grouped AVP identifies
4340 the vendor responsible for the assignment of the result code which
4341 follows. All Diameter answer messages defined in vendor-specific
4342 applications MUST include either one Result-Code AVP or one
4343 Experimental-Result AVP.
4345 7.7. Experimental-Result-Code AVP
4347 The Experimental-Result-Code AVP (AVP Code 298) is of type Unsigned32
4348 and contains a vendor-assigned value representing the result of
4349 processing the request.
4351 It is recommended that vendor-specific result codes follow the same
4352 conventions given for the Result-Code AVP regarding the different
4353 types of result codes and the handling of errors (for non 2xxx
4354 values).
4356 8. Diameter User Sessions
4358 In general, Diameter can provide two different types of services to
4359 applications. The first involves authentication and authorization,
4360 and can optionally make use of accounting. The second only makes use
4361 of accounting.
4363 When a service makes use of the authentication and/or authorization
4364 portion of an application, and a user requests access to the network,
4365 the Diameter client issues an auth request to its local server. The
4366 auth request is defined in a service specific Diameter application
4367 (e.g., NASREQ). The request contains a Session-Id AVP, which is used
4368 in subsequent messages (e.g., subsequent authorization, accounting,
4369 etc) relating to the user's session. The Session-Id AVP is a means
4370 for the client and servers to correlate a Diameter message with a
4371 user session.
4373 When a Diameter server authorizes a user to use network resources for
4374 a finite amount of time, and it is willing to extend the
4375 authorization via a future request, it MUST add the Authorization-
4376 Lifetime AVP to the answer message. The Authorization-Lifetime AVP
4377 defines the maximum number of seconds a user MAY make use of the
4378 resources before another authorization request is expected by the
4379 server. The Auth-Grace-Period AVP contains the number of seconds
4380 following the expiration of the Authorization-Lifetime, after which
4381 the server will release all state information related to the user's
4382 session. Note that if payment for services is expected by the
4383 serving realm from the user's home realm, the Authorization-Lifetime
4384 AVP, combined with the Auth-Grace-Period AVP, implies the maximum
4385 length of the session the home realm is willing to be fiscally
4386 responsible for. Services provided past the expiration of the
4387 Authorization-Lifetime and Auth-Grace-Period AVPs are the
4388 responsibility of the access device. Of course, the actual cost of
4389 services rendered is clearly outside the scope of the protocol.
4391 An access device that does not expect to send a re-authorization or a
4392 session termination request to the server MAY include the Auth-
4393 Session-State AVP with the value set to NO_STATE_MAINTAINED as a hint
4394 to the server. If the server accepts the hint, it agrees that since
4395 no session termination message will be received once service to the
4396 user is terminated, it cannot maintain state for the session. If the
4397 answer message from the server contains a different value in the
4398 Auth-Session-State AVP (or the default value if the AVP is absent),
4399 the access device MUST follow the server's directives. Note that the
4400 value NO_STATE_MAINTAINED MUST NOT be set in subsequent re-
4401 authorization requests and answers.
4403 The base protocol does not include any authorization request
4404 messages, since these are largely application-specific and are
4405 defined in a Diameter application document. However, the base
4406 protocol does define a set of messages that is used to terminate user
4407 sessions. These are used to allow servers that maintain state
4408 information to free resources.
4410 When a service only makes use of the Accounting portion of the
4411 Diameter protocol, even in combination with an application, the
4412 Session-Id is still used to identify user sessions. However, the
4413 session termination messages are not used, since a session is
4414 signaled as being terminated by issuing an accounting stop message.
4416 Diameter may also be used for services that cannot be easily
4417 categorized as authentication, authorization or accounting (e.g.,
4418 certain 3GPP IMS interfaces). In such cases, the finite state
4419 machine defined in subsequent sections may not be applicable.
4420 Therefore, the applications itself MAY need to define its own finite
4421 state machine. However, such application specific statemachines MUST
4422 comply with general Diameter user session requirements such co-
4423 relating all message exchanges via Session-Id AVP.
4425 8.1. Authorization Session State Machine
4427 This section contains a set of finite state machines, representing
4428 the life cycle of Diameter sessions, and which MUST be observed by
4429 all Diameter implementations that make use of the authentication
4430 and/or authorization portion of a Diameter application. The term
4431 Service-Specific below refers to a message defined in a Diameter
4432 application (e.g., Mobile IPv4, NASREQ).
4434 There are four different authorization session state machines
4435 supported in the Diameter base protocol. The first two describe a
4436 session in which the server is maintaining session state, indicated
4437 by the value of the Auth-Session-State AVP (or its absence). One
4438 describes the session from a client perspective, the other from a
4439 server perspective. The second two state machines are used when the
4440 server does not maintain session state. Here again, one describes
4441 the session from a client perspective, the other from a server
4442 perspective.
4444 When a session is moved to the Idle state, any resources that were
4445 allocated for the particular session must be released. Any event not
4446 listed in the state machines MUST be considered as an error
4447 condition, and an answer, if applicable, MUST be returned to the
4448 originator of the message.
4450 In the case that an application does not support re-auth, the state
4451 transitions related to server-initiated re-auth when both client and
4452 server sessions maintains state (e.g., Send RAR, Pending, Receive
4453 RAA) MAY be ignored.
4455 In the state table, the event 'Failure to send X' means that the
4456 Diameter agent is unable to send command X to the desired
4457 destination. This could be due to the peer being down, or due to the
4458 peer sending back a transient failure or temporary protocol error
4459 notification DIAMETER_TOO_BUSY or DIAMETER_LOOP_DETECTED in the
4460 Result-Code AVP of the corresponding Answer command. The event 'X
4461 successfully sent' is the complement of 'Failure to send X'.
4463 The following state machine is observed by a client when state is
4464 maintained on the server:
4466 CLIENT, STATEFUL
4467 State Event Action New State
4468 -------------------------------------------------------------
4469 Idle Client or Device Requests Send Pending
4470 access service
4471 specific
4472 auth req
4474 Idle ASR Received Send ASA Idle
4475 for unknown session with
4476 Result-Code
4477 = UNKNOWN_
4478 SESSION_ID
4480 Idle RAR Received Send RAA Idle
4481 for unknown session with
4482 Result-Code
4483 = UNKNOWN_
4484 SESSION_ID
4486 Pending Successful Service-specific Grant Open
4487 authorization answer Access
4488 received with default
4489 Auth-Session-State value
4491 Pending Successful Service-specific Sent STR Discon
4492 authorization answer received
4493 but service not provided
4495 Pending Error processing successful Sent STR Discon
4496 Service-specific authorization
4497 answer
4499 Pending Failed Service-specific Cleanup Idle
4500 authorization answer received
4502 Open User or client device Send Open
4503 requests access to service service
4504 specific
4505 auth req
4507 Open Successful Service-specific Provide Open
4508 authorization answer received Service
4510 Open Failed Service-specific Discon. Idle
4511 authorization answer user/device
4512 received.
4514 Open RAR received and client will Send RAA Open
4515 perform subsequent re-auth with
4516 Result-Code
4517 = SUCCESS
4519 Open RAR received and client will Send RAA Idle
4520 not perform subsequent with
4521 re-auth Result-Code
4522 != SUCCESS,
4523 Discon.
4524 user/device
4526 Open Session-Timeout Expires on Send STR Discon
4527 Access Device
4529 Open ASR Received, Send ASA Discon
4530 client will comply with with
4531 request to end the session Result-Code
4532 = SUCCESS,
4533 Send STR.
4535 Open ASR Received, Send ASA Open
4536 client will not comply with with
4537 request to end the session Result-Code
4538 != SUCCESS
4540 Open Authorization-Lifetime + Send STR Discon
4541 Auth-Grace-Period expires on
4542 access device
4544 Discon ASR Received Send ASA Discon
4546 Discon STA Received Discon. Idle
4547 user/device
4549 The following state machine is observed by a server when it is
4550 maintaining state for the session:
4552 SERVER, STATEFUL
4553 State Event Action New State
4554 -------------------------------------------------------------
4555 Idle Service-specific authorization Send Open
4556 request received, and successful
4557 user is authorized serv.
4558 specific
4559 answer
4561 Idle Service-specific authorization Send Idle
4562 request received, and failed serv.
4563 user is not authorized specific
4564 answer
4566 Open Service-specific authorization Send Open
4567 request received, and user successful
4568 is authorized serv. specific
4569 answer
4571 Open Service-specific authorization Send Idle
4572 request received, and user failed serv.
4573 is not authorized specific
4574 answer,
4575 Cleanup
4577 Open Home server wants to confirm Send RAR Pending
4578 authentication and/or
4579 authorization of the user
4581 Pending Received RAA with a failed Cleanup Idle
4582 Result-Code
4584 Pending Received RAA with Result-Code Update Open
4585 = SUCCESS session
4587 Open Home server wants to Send ASR Discon
4588 terminate the service
4590 Open Authorization-Lifetime (and Cleanup Idle
4591 Auth-Grace-Period) expires
4592 on home server.
4594 Open Session-Timeout expires on Cleanup Idle
4595 home server
4597 Discon Failure to send ASR Wait, Discon
4598 resend ASR
4600 Discon ASR successfully sent and Cleanup Idle
4601 ASA Received with Result-Code
4603 Not ASA Received None No Change.
4604 Discon
4606 Any STR Received Send STA, Idle
4607 Cleanup.
4609 The following state machine is observed by a client when state is not
4610 maintained on the server:
4612 CLIENT, STATELESS
4613 State Event Action New State
4614 -------------------------------------------------------------
4615 Idle Client or Device Requests Send Pending
4616 access service
4617 specific
4618 auth req
4620 Pending Successful Service-specific Grant Open
4621 authorization answer Access
4622 received with Auth-Session-
4623 State set to
4624 NO_STATE_MAINTAINED
4626 Pending Failed Service-specific Cleanup Idle
4627 authorization answer
4628 received
4630 Open Session-Timeout Expires on Discon. Idle
4631 Access Device user/device
4633 Open Service to user is terminated Discon. Idle
4634 user/device
4636 The following state machine is observed by a server when it is not
4637 maintaining state for the session:
4639 SERVER, STATELESS
4640 State Event Action New State
4641 -------------------------------------------------------------
4642 Idle Service-specific authorization Send serv. Idle
4643 request received, and specific
4644 successfully processed answer
4646 8.2. Accounting Session State Machine
4648 The following state machines MUST be supported for applications that
4649 have an accounting portion or that require only accounting services.
4650 The first state machine is to be observed by clients.
4652 See Section 9.7 for Accounting Command Codes and Section 9.8 for
4653 Accounting AVPs.
4655 The server side in the accounting state machine depends in some cases
4656 on the particular application. The Diameter base protocol defines a
4657 default state machine that MUST be followed by all applications that
4658 have not specified other state machines. This is the second state
4659 machine in this section described below.
4661 The default server side state machine requires the reception of
4662 accounting records in any order and at any time, and does not place
4663 any standards requirement on the processing of these records.
4664 Implementations of Diameter MAY perform checking, ordering,
4665 correlation, fraud detection, and other tasks based on these records.
4666 Both base Diameter AVPs as well as application specific AVPs MAY be
4667 inspected as a part of these tasks. The tasks can happen either
4668 immediately after record reception or in a post-processing phase.
4669 However, as these tasks are typically application or even policy
4670 dependent, they are not standardized by the Diameter specifications.
4671 Applications MAY define requirements on when to accept accounting
4672 records based on the used value of Accounting-Realtime-Required AVP,
4673 credit limits checks, and so on.
4675 However, the Diameter base protocol defines one optional server side
4676 state machine that MAY be followed by applications that require
4677 keeping track of the session state at the accounting server. Note
4678 that such tracking is incompatible with the ability to sustain long
4679 duration connectivity problems. Therefore, the use of this state
4680 machine is recommended only in applications where the value of the
4681 Accounting-Realtime-Required AVP is DELIVER_AND_GRANT, and hence
4682 accounting connectivity problems are required to cause the serviced
4683 user to be disconnected. Otherwise, records produced by the client
4684 may be lost by the server which no longer accepts them after the
4685 connectivity is re-established. This state machine is the third
4686 state machine in this section. The state machine is supervised by a
4687 supervision session timer Ts, which the value should be reasonably
4688 higher than the Acct_Interim_Interval value. Ts MAY be set to two
4689 times the value of the Acct_Interim_Interval so as to avoid the
4690 accounting session in the Diameter server to change to Idle state in
4691 case of short transient network failure.
4693 Any event not listed in the state machines MUST be considered as an
4694 error condition, and a corresponding answer, if applicable, MUST be
4695 returned to the originator of the message.
4697 In the state table, the event 'Failure to send' means that the
4698 Diameter client is unable to communicate with the desired
4699 destination. This could be due to the peer being down, or due to the
4700 peer sending back a transient failure or temporary protocol error
4701 notification DIAMETER_OUT_OF_SPACE, DIAMETER_TOO_BUSY, or
4702 DIAMETER_LOOP_DETECTED in the Result-Code AVP of the Accounting
4703 Answer command.
4705 The event 'Failed answer' means that the Diameter client received a
4706 non-transient failure notification in the Accounting Answer command.
4708 Note that the action 'Disconnect user/dev' MUST have an effect also
4709 to the authorization session state table, e.g., cause the STR message
4710 to be sent, if the given application has both authentication/
4711 authorization and accounting portions.
4713 The states PendingS, PendingI, PendingL, PendingE and PendingB stand
4714 for pending states to wait for an answer to an accounting request
4715 related to a Start, Interim, Stop, Event or buffered record,
4716 respectively.
4718 CLIENT, ACCOUNTING
4719 State Event Action New State
4720 -------------------------------------------------------------
4721 Idle Client or device requests Send PendingS
4722 access accounting
4723 start req.
4725 Idle Client or device requests Send PendingE
4726 a one-time service accounting
4727 event req
4729 Idle Records in storage Send PendingB
4730 record
4732 PendingS Successful accounting Open
4733 start answer received
4735 PendingS Failure to send and buffer Store Open
4736 space available and realtime Start
4737 not equal to DELIVER_AND_GRANT Record
4739 PendingS Failure to send and no buffer Open
4740 space available and realtime
4741 equal to GRANT_AND_LOSE
4743 PendingS Failure to send and no buffer Disconnect Idle
4744 space available and realtime user/dev
4745 not equal to
4746 GRANT_AND_LOSE
4748 PendingS Failed accounting start answer Open
4749 received and realtime equal
4750 to GRANT_AND_LOSE
4752 PendingS Failed accounting start answer Disconnect Idle
4753 received and realtime not user/dev
4754 equal to GRANT_AND_LOSE
4756 PendingS User service terminated Store PendingS
4757 stop
4758 record
4760 Open Interim interval elapses Send PendingI
4761 accounting
4762 interim
4763 record
4764 Open User service terminated Send PendingL
4765 accounting
4766 stop req.
4768 PendingI Successful accounting interim Open
4769 answer received
4771 PendingI Failure to send and (buffer Store Open
4772 space available or old record interim
4773 can be overwritten) and record
4774 realtime not equal to
4775 DELIVER_AND_GRANT
4777 PendingI Failure to send and no buffer Open
4778 space available and realtime
4779 equal to GRANT_AND_LOSE
4781 PendingI Failure to send and no buffer Disconnect Idle
4782 space available and realtime user/dev
4783 not equal to GRANT_AND_LOSE
4785 PendingI Failed accounting interim Open
4786 answer received and realtime
4787 equal to GRANT_AND_LOSE
4789 PendingI Failed accounting interim Disconnect Idle
4790 answer received and realtime user/dev
4791 not equal to GRANT_AND_LOSE
4793 PendingI User service terminated Store PendingI
4794 stop
4795 record
4796 PendingE Successful accounting Idle
4797 event answer received
4799 PendingE Failure to send and buffer Store Idle
4800 space available event
4801 record
4803 PendingE Failure to send and no buffer Idle
4804 space available
4806 PendingE Failed accounting event answer Idle
4807 received
4809 PendingB Successful accounting answer Delete Idle
4810 received record
4812 PendingB Failure to send Idle
4814 PendingB Failed accounting answer Delete Idle
4815 received record
4817 PendingL Successful accounting Idle
4818 stop answer received
4820 PendingL Failure to send and buffer Store Idle
4821 space available stop
4822 record
4824 PendingL Failure to send and no buffer Idle
4825 space available
4827 PendingL Failed accounting stop answer Idle
4828 received
4830 SERVER, STATELESS ACCOUNTING
4831 State Event Action New State
4832 -------------------------------------------------------------
4834 Idle Accounting start request Send Idle
4835 received, and successfully accounting
4836 processed. start
4837 answer
4839 Idle Accounting event request Send Idle
4840 received, and successfully accounting
4841 processed. event
4842 answer
4844 Idle Interim record received, Send Idle
4845 and successfully processed. accounting
4846 interim
4847 answer
4849 Idle Accounting stop request Send Idle
4850 received, and successfully accounting
4851 processed stop answer
4853 Idle Accounting request received, Send Idle
4854 no space left to store accounting
4855 records answer,
4856 Result-Code
4857 = OUT_OF_
4858 SPACE
4860 SERVER, STATEFUL ACCOUNTING
4861 State Event Action New State
4862 -------------------------------------------------------------
4864 Idle Accounting start request Send Open
4865 received, and successfully accounting
4866 processed. start
4867 answer,
4868 Start Ts
4870 Idle Accounting event request Send Idle
4871 received, and successfully accounting
4872 processed. event
4873 answer
4875 Idle Accounting request received, Send Idle
4876 no space left to store accounting
4877 records answer,
4878 Result-Code
4879 = OUT_OF_
4880 SPACE
4882 Open Interim record received, Send Open
4883 and successfully processed. accounting
4884 interim
4885 answer,
4886 Restart Ts
4888 Open Accounting stop request Send Idle
4889 received, and successfully accounting
4890 processed stop answer,
4891 Stop Ts
4893 Open Accounting request received, Send Idle
4894 no space left to store accounting
4895 records answer,
4896 Result-Code
4897 = OUT_OF_
4898 SPACE,
4899 Stop Ts
4901 Open Session supervision timer Ts Stop Ts Idle
4902 expired
4904 8.3. Server-Initiated Re-Auth
4906 A Diameter server may initiate a re-authentication and/or re-
4907 authorization service for a particular session by issuing a Re-Auth-
4908 Request (RAR).
4910 For example, for pre-paid services, the Diameter server that
4911 originally authorized a session may need some confirmation that the
4912 user is still using the services.
4914 An access device that receives a RAR message with Session-Id equal to
4915 a currently active session MUST initiate a re-auth towards the user,
4916 if the service supports this particular feature. Each Diameter
4917 application MUST state whether service-initiated re-auth is
4918 supported, since some applications do not allow access devices to
4919 prompt the user for re-auth.
4921 8.3.1. Re-Auth-Request
4923 The Re-Auth-Request (RAR), indicated by the Command-Code set to 258
4924 and the message flags' 'R' bit set, may be sent by any server to the
4925 access device that is providing session service, to request that the
4926 user be re-authenticated and/or re-authorized.
4928 Message Format
4930 ::= < Diameter Header: 258, REQ, PXY >
4931 < Session-Id >
4932 { Origin-Host }
4933 { Origin-Realm }
4934 { Destination-Realm }
4935 { Destination-Host }
4936 { Auth-Application-Id }
4937 { Re-Auth-Request-Type }
4938 [ User-Name ]
4939 [ Origin-State-Id ]
4940 * [ Proxy-Info ]
4941 * [ Route-Record ]
4942 * [ AVP ]
4944 8.3.2. Re-Auth-Answer
4946 The Re-Auth-Answer (RAA), indicated by the Command-Code set to 258
4947 and the message flags' 'R' bit clear, is sent in response to the RAR.
4948 The Result-Code AVP MUST be present, and indicates the disposition of
4949 the request.
4951 A successful RAA message MUST be followed by an application-specific
4952 authentication and/or authorization message.
4954 Message Format
4956 ::= < Diameter Header: 258, PXY >
4957 < Session-Id >
4958 { Result-Code }
4959 { Origin-Host }
4960 { Origin-Realm }
4961 [ User-Name ]
4962 [ Origin-State-Id ]
4963 [ Error-Message ]
4964 [ Error-Reporting-Host ]
4965 [ Failed-AVP ]
4966 * [ Redirect-Host ]
4967 [ Redirect-Host-Usage ]
4968 [ Redirect-Max-Cache-Time ]
4969 * [ Proxy-Info ]
4970 * [ AVP ]
4972 8.4. Session Termination
4974 It is necessary for a Diameter server that authorized a session, for
4975 which it is maintaining state, to be notified when that session is no
4976 longer active, both for tracking purposes as well as to allow
4977 stateful agents to release any resources that they may have provided
4978 for the user's session. For sessions whose state is not being
4979 maintained, this section is not used.
4981 When a user session that required Diameter authorization terminates,
4982 the access device that provided the service MUST issue a Session-
4983 Termination-Request (STR) message to the Diameter server that
4984 authorized the service, to notify it that the session is no longer
4985 active. An STR MUST be issued when a user session terminates for any
4986 reason, including user logoff, expiration of Session-Timeout,
4987 administrative action, termination upon receipt of an Abort-Session-
4988 Request (see below), orderly shutdown of the access device, etc.
4990 The access device also MUST issue an STR for a session that was
4991 authorized but never actually started. This could occur, for
4992 example, due to a sudden resource shortage in the access device, or
4993 because the access device is unwilling to provide the type of service
4994 requested in the authorization, or because the access device does not
4995 support a mandatory AVP returned in the authorization, etc.
4997 It is also possible that a session that was authorized is never
4998 actually started due to action of a proxy. For example, a proxy may
4999 modify an authorization answer, converting the result from success to
5000 failure, prior to forwarding the message to the access device. If
5001 the answer did not contain an Auth-Session-State AVP with the value
5002 NO_STATE_MAINTAINED, a proxy that causes an authorized session not to
5003 be started MUST issue an STR to the Diameter server that authorized
5004 the session, since the access device has no way of knowing that the
5005 session had been authorized.
5007 A Diameter server that receives an STR message MUST clean up
5008 resources (e.g., session state) associated with the Session-Id
5009 specified in the STR, and return a Session-Termination-Answer.
5011 A Diameter server also MUST clean up resources when the Session-
5012 Timeout expires, or when the Authorization-Lifetime and the Auth-
5013 Grace-Period AVPs expires without receipt of a re-authorization
5014 request, regardless of whether an STR for that session is received.
5015 The access device is not expected to provide service beyond the
5016 expiration of these timers; thus, expiration of either of these
5017 timers implies that the access device may have unexpectedly shut
5018 down.
5020 8.4.1. Session-Termination-Request
5022 The Session-Termination-Request (STR), indicated by the Command-Code
5023 set to 275 and the Command Flags' 'R' bit set, is sent by the access
5024 device to inform the Diameter Server that an authenticated and/or
5025 authorized session is being terminated.
5027 Message Format
5029 ::= < Diameter Header: 275, REQ, PXY >
5030 < Session-Id >
5031 { Origin-Host }
5032 { Origin-Realm }
5033 { Destination-Realm }
5034 { Auth-Application-Id }
5035 { Termination-Cause }
5036 [ User-Name ]
5037 [ Destination-Host ]
5038 * [ Class ]
5039 [ Origin-State-Id ]
5040 * [ Proxy-Info ]
5041 * [ Route-Record ]
5042 * [ AVP ]
5044 8.4.2. Session-Termination-Answer
5046 The Session-Termination-Answer (STA), indicated by the Command-Code
5047 set to 275 and the message flags' 'R' bit clear, is sent by the
5048 Diameter Server to acknowledge the notification that the session has
5049 been terminated. The Result-Code AVP MUST be present, and MAY
5050 contain an indication that an error occurred while servicing the STR.
5052 Upon sending or receipt of the STA, the Diameter Server MUST release
5053 all resources for the session indicated by the Session-Id AVP. Any
5054 intermediate server in the Proxy-Chain MAY also release any
5055 resources, if necessary.
5057 Message Format
5059 ::= < Diameter Header: 275, PXY >
5060 < Session-Id >
5061 { Result-Code }
5062 { Origin-Host }
5063 { Origin-Realm }
5064 [ User-Name ]
5065 * [ Class ]
5066 [ Error-Message ]
5067 [ Error-Reporting-Host ]
5068 [ Failed-AVP ]
5069 [ Origin-State-Id ]
5070 * [ Redirect-Host ]
5071 [ Redirect-Host-Usage ]
5072 ^
5073 [ Redirect-Max-Cache-Time ]
5074 * [ Proxy-Info ]
5075 * [ AVP ]
5077 8.5. Aborting a Session
5079 A Diameter server may request that the access device stop providing
5080 service for a particular session by issuing an Abort-Session-Request
5081 (ASR).
5083 For example, the Diameter server that originally authorized the
5084 session may be required to cause that session to be stopped for
5085 credit or other reasons that were not anticipated when the session
5086 was first authorized. On the other hand, an operator may maintain a
5087 management server for the purpose of issuing ASRs to administratively
5088 remove users from the network.
5090 An access device that receives an ASR with Session-ID equal to a
5091 currently active session MAY stop the session. Whether the access
5092 device stops the session or not is implementation- and/or
5093 configuration-dependent. For example, an access device may honor
5094 ASRs from certain agents only. In any case, the access device MUST
5095 respond with an Abort-Session-Answer, including a Result-Code AVP to
5096 indicate what action it took.
5098 Note that if the access device does stop the session upon receipt of
5099 an ASR, it issues an STR to the authorizing server (which may or may
5100 not be the agent issuing the ASR) just as it would if the session
5101 were terminated for any other reason.
5103 8.5.1. Abort-Session-Request
5105 The Abort-Session-Request (ASR), indicated by the Command-Code set to
5106 274 and the message flags' 'R' bit set, may be sent by any server to
5107 the access device that is providing session service, to request that
5108 the session identified by the Session-Id be stopped.
5110 Message Format
5112 ::= < Diameter Header: 274, REQ, PXY >
5113 < Session-Id >
5114 { Origin-Host }
5115 { Origin-Realm }
5116 { Destination-Realm }
5117 { Destination-Host }
5118 { Auth-Application-Id }
5119 [ User-Name ]
5120 [ Origin-State-Id ]
5121 * [ Proxy-Info ]
5122 * [ Route-Record ]
5123 * [ AVP ]
5125 8.5.2. Abort-Session-Answer
5127 The Abort-Session-Answer (ASA), indicated by the Command-Code set to
5128 274 and the message flags' 'R' bit clear, is sent in response to the
5129 ASR. The Result-Code AVP MUST be present, and indicates the
5130 disposition of the request.
5132 If the session identified by Session-Id in the ASR was successfully
5133 terminated, Result-Code is set to DIAMETER_SUCCESS. If the session
5134 is not currently active, Result-Code is set to
5135 DIAMETER_UNKNOWN_SESSION_ID. If the access device does not stop the
5136 session for any other reason, Result-Code is set to
5137 DIAMETER_UNABLE_TO_COMPLY.
5139 Message Format
5141 ::= < Diameter Header: 274, PXY >
5142 < Session-Id >
5143 { Result-Code }
5144 { Origin-Host }
5145 { Origin-Realm }
5146 [ User-Name ]
5147 [ Origin-State-Id ]
5148 [ Error-Message ]
5149 [ Error-Reporting-Host ]
5150 [ Failed-AVP ]
5151 * [ Redirect-Host ]
5152 [ Redirect-Host-Usage ]
5153 [ Redirect-Max-Cache-Time ]
5154 * [ Proxy-Info ]
5155 * [ AVP ]
5157 8.6. Inferring Session Termination from Origin-State-Id
5159 Origin-State-Id is used to allow rapid detection of terminated
5160 sessions for which no STR would have been issued, due to
5161 unanticipated shutdown of an access device.
5163 By including Origin-State-Id in CER/CEA messages, an access device
5164 allows a next-hop server to determine immediately upon connection
5165 whether the device has lost its sessions since the last connection.
5167 By including Origin-State-Id in request messages, an access device
5168 also allows a server with which it communicates via proxy to make
5169 such a determination. However, a server that is not directly
5170 connected with the access device will not discover that the access
5171 device has been restarted unless and until it receives a new request
5172 from the access device. Thus, use of this mechanism across proxies
5173 is opportunistic rather than reliable, but useful nonetheless.
5175 When a Diameter server receives an Origin-State-Id that is greater
5176 than the Origin-State-Id previously received from the same issuer, it
5177 may assume that the issuer has lost state since the previous message
5178 and that all sessions that were active under the lower Origin-State-
5179 Id have been terminated. The Diameter server MAY clean up all
5180 session state associated with such lost sessions, and MAY also issues
5181 STRs for all such lost sessions that were authorized on upstream
5182 servers, to allow session state to be cleaned up globally.
5184 8.7. Auth-Request-Type AVP
5186 The Auth-Request-Type AVP (AVP Code 274) is of type Enumerated and is
5187 included in application-specific auth requests to inform the peers
5188 whether a user is to be authenticated only, authorized only or both.
5189 Note any value other than both MAY cause RADIUS interoperability
5190 issues. The following values are defined:
5192 AUTHENTICATE_ONLY 1
5194 The request being sent is for authentication only, and MUST
5195 contain the relevant application specific authentication AVPs that
5196 are needed by the Diameter server to authenticate the user.
5198 AUTHORIZE_ONLY 2
5200 The request being sent is for authorization only, and MUST contain
5201 the application specific authorization AVPs that are necessary to
5202 identify the service being requested/offered.
5204 AUTHORIZE_AUTHENTICATE 3
5206 The request contains a request for both authentication and
5207 authorization. The request MUST include both the relevant
5208 application specific authentication information, and authorization
5209 information necessary to identify the service being requested/
5210 offered.
5212 8.8. Session-Id AVP
5214 The Session-Id AVP (AVP Code 263) is of type UTF8String and is used
5215 to identify a specific session (see Section 8). All messages
5216 pertaining to a specific session MUST include only one Session-Id AVP
5217 and the same value MUST be used throughout the life of a session.
5218 When present, the Session-Id SHOULD appear immediately following the
5219 Diameter Header (see Section 3).
5221 The Session-Id MUST be globally and eternally unique, as it is meant
5222 to uniquely identify a user session without reference to any other
5223 information, and may be needed to correlate historical authentication
5224 information with accounting information. The Session-Id includes a
5225 mandatory portion and an implementation-defined portion; a
5226 recommended format for the implementation-defined portion is outlined
5227 below.
5229 The Session-Id MUST begin with the sender's identity encoded in the
5230 DiameterIdentity type (see Section 4.4). The remainder of the
5231 Session-Id is delimited by a ";" character, and MAY be any sequence
5232 that the client can guarantee to be eternally unique; however, the
5233 following format is recommended, (square brackets [] indicate an
5234 optional element):
5236 ;;[;]
5238 and are decimal representations of the
5239 high and low 32 bits of a monotonically increasing 64-bit value. The
5240 64-bit value is rendered in two part to simplify formatting by 32-bit
5241 processors. At startup, the high 32 bits of the 64-bit value MAY be
5242 initialized to the time, and the low 32 bits MAY be initialized to
5243 zero. This will for practical purposes eliminate the possibility of
5244 overlapping Session-Ids after a reboot, assuming the reboot process
5245 takes longer than a second. Alternatively, an implementation MAY
5246 keep track of the increasing value in non-volatile memory.
5248 is implementation specific but may include a modem's
5249 device Id, a layer 2 address, timestamp, etc.
5251 Example, in which there is no optional value:
5253 accesspoint7.acme.com;1876543210;523
5255 Example, in which there is an optional value:
5257 accesspoint7.acme.com;1876543210;523;mobile@200.1.1.88
5259 The Session-Id is created by the Diameter application initiating the
5260 session, which in most cases is done by the client. Note that a
5261 Session-Id MAY be used for both the authorization and accounting
5262 commands of a given application.
5264 8.9. Authorization-Lifetime AVP
5266 The Authorization-Lifetime AVP (AVP Code 291) is of type Unsigned32
5267 and contains the maximum number of seconds of service to be provided
5268 to the user before the user is to be re-authenticated and/or re-
5269 authorized. Great care should be taken when the Authorization-
5270 Lifetime value is determined, since a low, non-zero, value could
5271 create significant Diameter traffic, which could congest both the
5272 network and the agents.
5274 A value of zero (0) means that immediate re-auth is necessary by the
5275 access device. This is typically used in cases where multiple
5276 authentication methods are used, and a successful auth response with
5277 this AVP set to zero is used to signal that the next authentication
5278 method is to be immediately initiated. The absence of this AVP, or a
5279 value of all ones (meaning all bits in the 32 bit field are set to
5280 one) means no re-auth is expected.
5282 If both this AVP and the Session-Timeout AVP are present in a
5283 message, the value of the latter MUST NOT be smaller than the
5284 Authorization-Lifetime AVP.
5286 An Authorization-Lifetime AVP MAY be present in re-authorization
5287 messages, and contains the number of seconds the user is authorized
5288 to receive service from the time the re-auth answer message is
5289 received by the access device.
5291 This AVP MAY be provided by the client as a hint of the maximum
5292 lifetime that it is willing to accept. However, the server MAY
5293 return a value that is equal to, or smaller, than the one provided by
5294 the client.
5296 8.10. Auth-Grace-Period AVP
5298 The Auth-Grace-Period AVP (AVP Code 276) is of type Unsigned32 and
5299 contains the number of seconds the Diameter server will wait
5300 following the expiration of the Authorization-Lifetime AVP before
5301 cleaning up resources for the session.
5303 8.11. Auth-Session-State AVP
5305 The Auth-Session-State AVP (AVP Code 277) is of type Enumerated and
5306 specifies whether state is maintained for a particular session. The
5307 client MAY include this AVP in requests as a hint to the server, but
5308 the value in the server's answer message is binding. The following
5309 values are supported:
5311 STATE_MAINTAINED 0
5313 This value is used to specify that session state is being
5314 maintained, and the access device MUST issue a session termination
5315 message when service to the user is terminated. This is the
5316 default value.
5318 NO_STATE_MAINTAINED 1
5320 This value is used to specify that no session termination messages
5321 will be sent by the access device upon expiration of the
5322 Authorization-Lifetime.
5324 8.12. Re-Auth-Request-Type AVP
5326 The Re-Auth-Request-Type AVP (AVP Code 285) is of type Enumerated and
5327 is included in application-specific auth answers to inform the client
5328 of the action expected upon expiration of the Authorization-Lifetime.
5329 If the answer message contains an Authorization-Lifetime AVP with a
5330 positive value, the Re-Auth-Request-Type AVP MUST be present in an
5331 answer message. The following values are defined:
5333 AUTHORIZE_ONLY 0
5335 An authorization only re-auth is expected upon expiration of the
5336 Authorization-Lifetime. This is the default value if the AVP is
5337 not present in answer messages that include the Authorization-
5338 Lifetime.
5340 AUTHORIZE_AUTHENTICATE 1
5342 An authentication and authorization re-auth is expected upon
5343 expiration of the Authorization-Lifetime.
5345 8.13. Session-Timeout AVP
5347 The Session-Timeout AVP (AVP Code 27) [RFC2865] is of type Unsigned32
5348 and contains the maximum number of seconds of service to be provided
5349 to the user before termination of the session. When both the
5350 Session-Timeout and the Authorization-Lifetime AVPs are present in an
5351 answer message, the former MUST be equal to or greater than the value
5352 of the latter.
5354 A session that terminates on an access device due to the expiration
5355 of the Session-Timeout MUST cause an STR to be issued, unless both
5356 the access device and the home server had previously agreed that no
5357 session termination messages would be sent (see Section 8.9).
5359 A Session-Timeout AVP MAY be present in a re-authorization answer
5360 message, and contains the remaining number of seconds from the
5361 beginning of the re-auth.
5363 A value of zero, or the absence of this AVP, means that this session
5364 has an unlimited number of seconds before termination.
5366 This AVP MAY be provided by the client as a hint of the maximum
5367 timeout that it is willing to accept. However, the server MAY return
5368 a value that is equal to, or smaller, than the one provided by the
5369 client.
5371 8.14. User-Name AVP
5373 The User-Name AVP (AVP Code 1) [RFC2865] is of type UTF8String, which
5374 contains the User-Name, in a format consistent with the NAI
5375 specification [RFC4282].
5377 8.15. Termination-Cause AVP
5379 The Termination-Cause AVP (AVP Code 295) is of type Enumerated, and
5380 is used to indicate the reason why a session was terminated on the
5381 access device. The following values are defined:
5383 DIAMETER_LOGOUT 1
5385 The user initiated a disconnect
5387 DIAMETER_SERVICE_NOT_PROVIDED 2
5389 This value is used when the user disconnected prior to the receipt
5390 of the authorization answer message.
5392 DIAMETER_BAD_ANSWER 3
5394 This value indicates that the authorization answer received by the
5395 access device was not processed successfully.
5397 DIAMETER_ADMINISTRATIVE 4
5399 The user was not granted access, or was disconnected, due to
5400 administrative reasons, such as the receipt of a Abort-Session-
5401 Request message.
5403 DIAMETER_LINK_BROKEN 5
5405 The communication to the user was abruptly disconnected.
5407 DIAMETER_AUTH_EXPIRED 6
5409 The user's access was terminated since its authorized session time
5410 has expired.
5412 DIAMETER_USER_MOVED 7
5414 The user is receiving services from another access device.
5416 DIAMETER_SESSION_TIMEOUT 8
5418 The user's session has timed out, and service has been terminated.
5420 8.16. Origin-State-Id AVP
5422 The Origin-State-Id AVP (AVP Code 278), of type Unsigned32, is a
5423 monotonically increasing value that is advanced whenever a Diameter
5424 entity restarts with loss of previous state, for example upon reboot.
5425 Origin-State-Id MAY be included in any Diameter message, including
5426 CER.
5428 A Diameter entity issuing this AVP MUST create a higher value for
5429 this AVP each time its state is reset. A Diameter entity MAY set
5430 Origin-State-Id to the time of startup, or it MAY use an incrementing
5431 counter retained in non-volatile memory across restarts.
5433 The Origin-State-Id, if present, MUST reflect the state of the entity
5434 indicated by Origin-Host. If a proxy modifies Origin-Host, it MUST
5435 either remove Origin-State-Id or modify it appropriately as well.
5436 Typically, Origin-State-Id is used by an access device that always
5437 starts up with no active sessions; that is, any session active prior
5438 to restart will have been lost. By including Origin-State-Id in a
5439 message, it allows other Diameter entities to infer that sessions
5440 associated with a lower Origin-State-Id are no longer active. If an
5441 access device does not intend for such inferences to be made, it MUST
5442 either not include Origin-State-Id in any message, or set its value
5443 to 0.
5445 8.17. Session-Binding AVP
5447 The Session-Binding AVP (AVP Code 270) is of type Unsigned32, and MAY
5448 be present in application-specific authorization answer messages. If
5449 present, this AVP MAY inform the Diameter client that all future
5450 application-specific re-auth messages for this session MUST be sent
5451 to the same authorization server. This AVP MAY also specify that a
5452 Session-Termination-Request message for this session MUST be sent to
5453 the same authorizing server.
5455 This field is a bit mask, and the following bits have been defined:
5457 RE_AUTH 1
5459 When set, future re-auth messages for this session MUST NOT
5460 include the Destination-Host AVP. When cleared, the default
5461 value, the Destination-Host AVP MUST be present in all re-auth
5462 messages for this session.
5464 STR 2
5466 When set, the STR message for this session MUST NOT include the
5467 Destination-Host AVP. When cleared, the default value, the
5468 Destination-Host AVP MUST be present in the STR message for this
5469 session.
5471 ACCOUNTING 4
5473 When set, all accounting messages for this session MUST NOT
5474 include the Destination-Host AVP. When cleared, the default
5475 value, the Destination-Host AVP, if known, MUST be present in all
5476 accounting messages for this session.
5478 8.18. Session-Server-Failover AVP
5480 The Session-Server-Failover AVP (AVP Code 271) is of type Enumerated,
5481 and MAY be present in application-specific authorization answer
5482 messages that either do not include the Session-Binding AVP or
5483 include the Session-Binding AVP with any of the bits set to a zero
5484 value. If present, this AVP MAY inform the Diameter client that if a
5485 re-auth or STR message fails due to a delivery problem, the Diameter
5486 client SHOULD issue a subsequent message without the Destination-Host
5487 AVP. When absent, the default value is REFUSE_SERVICE.
5489 The following values are supported:
5491 REFUSE_SERVICE 0
5493 If either the re-auth or the STR message delivery fails, terminate
5494 service with the user, and do not attempt any subsequent attempts.
5496 TRY_AGAIN 1
5498 If either the re-auth or the STR message delivery fails, resend
5499 the failed message without the Destination-Host AVP present.
5501 ALLOW_SERVICE 2
5503 If re-auth message delivery fails, assume that re-authorization
5504 succeeded. If STR message delivery fails, terminate the session.
5506 TRY_AGAIN_ALLOW_SERVICE 3
5508 If either the re-auth or the STR message delivery fails, resend
5509 the failed message without the Destination-Host AVP present. If
5510 the second delivery fails for re-auth, assume re-authorization
5511 succeeded. If the second delivery fails for STR, terminate the
5512 session.
5514 8.19. Multi-Round-Time-Out AVP
5516 The Multi-Round-Time-Out AVP (AVP Code 272) is of type Unsigned32,
5517 and SHOULD be present in application-specific authorization answer
5518 messages whose Result-Code AVP is set to DIAMETER_MULTI_ROUND_AUTH.
5519 This AVP contains the maximum number of seconds that the access
5520 device MUST provide the user in responding to an authentication
5521 request.
5523 8.20. Class AVP
5525 The Class AVP (AVP Code 25) is of type OctetString and is used to by
5526 Diameter servers to return state information to the access device.
5527 When one or more Class AVPs are present in application-specific
5528 authorization answer messages, they MUST be present in subsequent re-
5529 authorization, session termination and accounting messages. Class
5530 AVPs found in a re-authorization answer message override the ones
5531 found in any previous authorization answer message. Diameter server
5532 implementations SHOULD NOT return Class AVPs that require more than
5533 4096 bytes of storage on the Diameter client. A Diameter client that
5534 receives Class AVPs whose size exceeds local available storage MUST
5535 terminate the session.
5537 8.21. Event-Timestamp AVP
5539 The Event-Timestamp (AVP Code 55) is of type Time, and MAY be
5540 included in an Accounting-Request and Accounting-Answer messages to
5541 record the time that the reported event occurred, in seconds since
5542 January 1, 1900 00:00 UTC.
5544 9. Accounting
5546 This accounting protocol is based on a server directed model with
5547 capabilities for real-time delivery of accounting information.
5548 Several fault resilience methods [RFC2975] have been built in to the
5549 protocol in order minimize loss of accounting data in various fault
5550 situations and under different assumptions about the capabilities of
5551 the used devices.
5553 9.1. Server Directed Model
5555 The server directed model means that the device generating the
5556 accounting data gets information from either the authorization server
5557 (if contacted) or the accounting server regarding the way accounting
5558 data shall be forwarded. This information includes accounting record
5559 timeliness requirements.
5561 As discussed in [RFC2975], real-time transfer of accounting records
5562 is a requirement, such as the need to perform credit limit checks and
5563 fraud detection. Note that batch accounting is not a requirement,
5564 and is therefore not supported by Diameter. Should batched
5565 accounting be required in the future, a new Diameter application will
5566 need to be created, or it could be handled using another protocol.
5567 Note, however, that even if at the Diameter layer accounting requests
5568 are processed one by one, transport protocols used under Diameter
5569 typically batch several requests in the same packet under heavy
5570 traffic conditions. This may be sufficient for many applications.
5572 The authorization server (chain) directs the selection of proper
5573 transfer strategy, based on its knowledge of the user and
5574 relationships of roaming partnerships. The server (or agents) uses
5575 the Acct-Interim-Interval and Accounting-Realtime-Required AVPs to
5576 control the operation of the Diameter peer operating as a client.
5577 The Acct-Interim-Interval AVP, when present, instructs the Diameter
5578 node acting as a client to produce accounting records continuously
5579 even during a session. Accounting-Realtime-Required AVP is used to
5580 control the behavior of the client when the transfer of accounting
5581 records from the Diameter client is delayed or unsuccessful.
5583 The Diameter accounting server MAY override the interim interval or
5584 the realtime requirements by including the Acct-Interim-Interval or
5585 Accounting-Realtime-Required AVP in the Accounting-Answer message.
5586 When one of these AVPs is present, the latest value received SHOULD
5587 be used in further accounting activities for the same session.
5589 9.2. Protocol Messages
5591 A Diameter node that receives a successful authentication and/or
5592 authorization messages from the Home AAA server MUST collect
5593 accounting information for the session. The Accounting-Request
5594 message is used to transmit the accounting information to the Home
5595 AAA server, which MUST reply with the Accounting-Answer message to
5596 confirm reception. The Accounting-Answer message includes the
5597 Result-Code AVP, which MAY indicate that an error was present in the
5598 accounting message. A rejected Accounting-Request message MAY cause
5599 the user's session to be terminated, depending on the value of the
5600 Accounting-Realtime-Required AVP received earlier for the session in
5601 question.
5603 Each Diameter Accounting protocol message MAY be compressed, in order
5604 to reduce network bandwidth usage. If TLS is used to secure the
5605 Diameter session, then TLS compression [RFC4346] MAY be used.
5607 9.3. Accounting Application Extension and Requirements
5609 Each Diameter application (e.g., NASREQ, MobileIP), MUST define their
5610 Service-Specific AVPs that MUST be present in the Accounting-Request
5611 message in a section entitled "Accounting AVPs". The application
5612 MUST assume that the AVPs described in this document will be present
5613 in all Accounting messages, so only their respective service-specific
5614 AVPs need to be defined in this section.
5616 Applications have the option of using one or both of the following
5617 accounting application extension models:
5619 Split Accounting Service
5621 The accounting message will carry the application identifier of
5622 the Diameter base accounting application (see Section 2.4).
5623 Accounting messages maybe routed to Diameter nodes other than the
5624 corresponding Diameter application. These nodes might be
5625 centralized accounting servers that provide accounting service for
5626 multiple different Diameter applications. These nodes MUST
5627 advertise the Diameter base accounting application identifier
5628 during capabilities exchange.
5630 Accounting messages which uses the Diameter base accounting
5631 application identifier in its header MUST include the application
5632 identifier of the Diameter application it is providing service for
5633 in the Acct-Application-Id AVP. This allows the accounting server
5634 to determine which Diameter application the accounting records are
5635 for.
5637 Coupled Accounting Service
5639 The accounting messages will carry the application identifier of
5640 the application that is using it. The application itself will
5641 process the received accounting records or forward them to an
5642 accounting server. There is no accounting application
5643 advertisement required during capabilities exchange and the
5644 accounting messages will be routed the same as any of the other
5645 application messages.
5647 In cases where an application does not define its own accounting
5648 service, it is preferred that the split accounting model be used.
5650 9.4. Fault Resilience
5652 Diameter Base protocol mechanisms are used to overcome small message
5653 loss and network faults of temporary nature.
5655 Diameter peers acting as clients MUST implement the use of failover
5656 to guard against server failures and certain network failures.
5657 Diameter peers acting as agents or related off-line processing
5658 systems MUST detect duplicate accounting records caused by the
5659 sending of same record to several servers and duplication of messages
5660 in transit. This detection MUST be based on the inspection of the
5661 Session-Id and Accounting-Record-Number AVP pairs. Appendix C
5662 discusses duplicate detection needs and implementation issues.
5664 Diameter clients MAY have non-volatile memory for the safe storage of
5665 accounting records over reboots or extended network failures, network
5666 partitions, and server failures. If such memory is available, the
5667 client SHOULD store new accounting records there as soon as the
5668 records are created and until a positive acknowledgement of their
5669 reception from the Diameter Server has been received. Upon a reboot,
5670 the client MUST starting sending the records in the non-volatile
5671 memory to the accounting server with appropriate modifications in
5672 termination cause, session length, and other relevant information in
5673 the records.
5675 A further application of this protocol may include AVPs to control
5676 how many accounting records may at most be stored in the Diameter
5677 client without committing them to the non-volatile memory or
5678 transferring them to the Diameter server.
5680 The client SHOULD NOT remove the accounting data from any of its
5681 memory areas before the correct Accounting-Answer has been received.
5682 The client MAY remove oldest, undelivered or yet unacknowledged
5683 accounting data if it runs out of resources such as memory. It is an
5684 implementation dependent matter for the client to accept new sessions
5685 under this condition.
5687 9.5. Accounting Records
5689 In all accounting records, the Session-Id AVP MUST be present; the
5690 User-Name AVP MUST be present if it is available to the Diameter
5691 client.
5693 Different types of accounting records are sent depending on the
5694 actual type of accounted service and the authorization server's
5695 directions for interim accounting. If the accounted service is a
5696 one-time event, meaning that the start and stop of the event are
5697 simultaneous, then the Accounting-Record-Type AVP MUST be present and
5698 set to the value EVENT_RECORD.
5700 If the accounted service is of a measurable length, then the AVP MUST
5701 use the values START_RECORD, STOP_RECORD, and possibly,
5702 INTERIM_RECORD. If the authorization server has not directed interim
5703 accounting to be enabled for the session, two accounting records MUST
5704 be generated for each service of type session. When the initial
5705 Accounting-Request for a given session is sent, the Accounting-
5706 Record-Type AVP MUST be set to the value START_RECORD. When the last
5707 Accounting-Request is sent, the value MUST be STOP_RECORD.
5709 If the authorization server has directed interim accounting to be
5710 enabled, the Diameter client MUST produce additional records between
5711 the START_RECORD and STOP_RECORD, marked INTERIM_RECORD. The
5712 production of these records is directed by Acct-Interim-Interval as
5713 well as any re-authentication or re-authorization of the session.
5714 The Diameter client MUST overwrite any previous interim accounting
5715 records that are locally stored for delivery, if a new record is
5716 being generated for the same session. This ensures that only one
5717 pending interim record can exist on an access device for any given
5718 session.
5720 A particular value of Accounting-Sub-Session-Id MUST appear only in
5721 one sequence of accounting records from a DIAMETER client, except for
5722 the purposes of retransmission. The one sequence that is sent MUST
5723 be either one record with Accounting-Record-Type AVP set to the value
5724 EVENT_RECORD, or several records starting with one having the value
5725 START_RECORD, followed by zero or more INTERIM_RECORD and a single
5726 STOP_RECORD. A particular Diameter application specification MUST
5727 define the type of sequences that MUST be used.
5729 9.6. Correlation of Accounting Records
5731 The Diameter protocol's Session-Id AVP, which is globally unique (see
5732 Section 8.8), is used during the authorization phase to identify a
5733 particular session. Services that do not require any authorization
5734 still use the Session-Id AVP to identify sessions. Accounting
5735 messages MAY use a different Session-Id from that sent in
5736 authorization messages. Specific applications MAY require different
5737 a Session-ID for accounting messages.
5739 However, there are certain applications that require multiple
5740 accounting sub-sessions. Such applications would send messages with
5741 a constant Session-Id AVP, but a different Accounting-Sub-Session-Id
5742 AVP. In these cases, correlation is performed using the Session-Id.
5743 It is important to note that receiving a STOP_RECORD with no
5744 Accounting-Sub-Session-Id AVP when sub-sessions were originally used
5745 in the START_RECORD messages implies that all sub-sessions are
5746 terminated.
5748 Furthermore, there are certain applications where a user receives
5749 service from different access devices (e.g., Mobile IPv4), each with
5750 their own unique Session-Id. In such cases, the Acct-Multi-Session-
5751 Id AVP is used for correlation. During authorization, a server that
5752 determines that a request is for an existing session SHOULD include
5753 the Acct-Multi-Session-Id AVP, which the access device MUST include
5754 in all subsequent accounting messages.
5756 The Acct-Multi-Session-Id AVP MAY include the value of the original
5757 Session-Id. It's contents are implementation specific, but MUST be
5758 globally unique across other Acct-Multi-Session-Id, and MUST NOT
5759 change during the life of a session.
5761 A Diameter application document MUST define the exact concept of a
5762 session that is being accounted, and MAY define the concept of a
5763 multi-session. For instance, the NASREQ DIAMETER application treats
5764 a single PPP connection to a Network Access Server as one session,
5765 and a set of Multilink PPP sessions as one multi-session.
5767 9.7. Accounting Command-Codes
5769 This section defines Command-Code values that MUST be supported by
5770 all Diameter implementations that provide Accounting services.
5772 9.7.1. Accounting-Request
5774 The Accounting-Request (ACR) command, indicated by the Command-Code
5775 field set to 271 and the Command Flags' 'R' bit set, is sent by a
5776 Diameter node, acting as a client, in order to exchange accounting
5777 information with a peer.
5779 One of Acct-Application-Id and Vendor-Specific-Application-Id AVPs
5780 MUST be present. If the Vendor-Specific-Application-Id grouped AVP
5781 is present, it must have an Acct-Application-Id inside.
5783 The AVP listed below SHOULD include service specific accounting AVPs,
5784 as described in Section 9.3.
5786 Message Format
5788 ::= < Diameter Header: 271, REQ, PXY >
5789 < Session-Id >
5790 { Origin-Host }
5791 { Origin-Realm }
5792 { Destination-Realm }
5793 { Accounting-Record-Type }
5794 { Accounting-Record-Number }
5795 [ Acct-Application-Id ]
5796 [ Vendor-Specific-Application-Id ]
5797 [ User-Name ]
5798 [ Destination-Host ]
5799 [ Accounting-Sub-Session-Id ]
5800 [ Acct-Session-Id ]
5801 [ Acct-Multi-Session-Id ]
5802 [ Acct-Interim-Interval ]
5803 [ Accounting-Realtime-Required ]
5804 [ Origin-State-Id ]
5805 [ Event-Timestamp ]
5806 * [ Proxy-Info ]
5807 * [ Route-Record ]
5808 * [ AVP ]
5810 9.7.2. Accounting-Answer
5812 The Accounting-Answer (ACA) command, indicated by the Command-Code
5813 field set to 271 and the Command Flags' 'R' bit cleared, is used to
5814 acknowledge an Accounting-Request command. The Accounting-Answer
5815 command contains the same Session-Id as the corresponding request.
5817 Only the target Diameter Server, known as the home Diameter Server,
5818 SHOULD respond with the Accounting-Answer command.
5820 One of Acct-Application-Id and Vendor-Specific-Application-Id AVPs
5821 MUST be present. If the Vendor-Specific-Application-Id grouped AVP
5822 is present, it must have an Acct-Application-Id inside.
5824 The AVP listed below SHOULD include service specific accounting AVPs,
5825 as described in Section 9.3.
5827 Message Format
5829 ::= < Diameter Header: 271, PXY >
5830 < Session-Id >
5831 { Result-Code }
5832 { Origin-Host }
5833 { Origin-Realm }
5834 { Accounting-Record-Type }
5835 { Accounting-Record-Number }
5836 [ Acct-Application-Id ]
5837 [ Vendor-Specific-Application-Id ]
5838 [ User-Name ]
5839 [ Accounting-Sub-Session-Id ]
5840 [ Acct-Session-Id ]
5841 [ Acct-Multi-Session-Id ]
5842 [ Error-Message ]
5843 [ Error-Reporting-Host ]
5844 [ Failed-AVP ]
5845 [ Acct-Interim-Interval ]
5846 [ Accounting-Realtime-Required ]
5847 [ Origin-State-Id ]
5848 [ Event-Timestamp ]
5849 * [ Proxy-Info ]
5850 * [ AVP ]
5852 9.8. Accounting AVPs
5854 This section contains AVPs that describe accounting usage information
5855 related to a specific session.
5857 9.8.1. Accounting-Record-Type AVP
5859 The Accounting-Record-Type AVP (AVP Code 480) is of type Enumerated
5860 and contains the type of accounting record being sent. The following
5861 values are currently defined for the Accounting-Record-Type AVP:
5863 EVENT_RECORD 1
5865 An Accounting Event Record is used to indicate that a one-time
5866 event has occurred (meaning that the start and end of the event
5867 are simultaneous). This record contains all information relevant
5868 to the service, and is the only record of the service.
5870 START_RECORD 2
5872 An Accounting Start, Interim, and Stop Records are used to
5873 indicate that a service of a measurable length has been given. An
5874 Accounting Start Record is used to initiate an accounting session,
5875 and contains accounting information that is relevant to the
5876 initiation of the session.
5878 INTERIM_RECORD 3
5880 An Interim Accounting Record contains cumulative accounting
5881 information for an existing accounting session. Interim
5882 Accounting Records SHOULD be sent every time a re-authentication
5883 or re-authorization occurs. Further, additional interim record
5884 triggers MAY be defined by application-specific Diameter
5885 applications. The selection of whether to use INTERIM_RECORD
5886 records is done by the Acct-Interim-Interval AVP.
5888 STOP_RECORD 4
5890 An Accounting Stop Record is sent to terminate an accounting
5891 session and contains cumulative accounting information relevant to
5892 the existing session.
5894 9.8.2. Acct-Interim-Interval
5896 The Acct-Interim-Interval AVP (AVP Code 85) is of type Unsigned32 and
5897 is sent from the Diameter home authorization server to the Diameter
5898 client. The client uses information in this AVP to decide how and
5899 when to produce accounting records. With different values in this
5900 AVP, service sessions can result in one, two, or two+N accounting
5901 records, based on the needs of the home-organization. The following
5902 accounting record production behavior is directed by the inclusion of
5903 this AVP:
5905 1. The omission of the Acct-Interim-Interval AVP or its inclusion
5906 with Value field set to 0 means that EVENT_RECORD, START_RECORD,
5907 and STOP_RECORD are produced, as appropriate for the service.
5909 2. The inclusion of the AVP with Value field set to a non-zero value
5910 means that INTERIM_RECORD records MUST be produced between the
5911 START_RECORD and STOP_RECORD records. The Value field of this
5912 AVP is the nominal interval between these records in seconds.
5914 The Diameter node that originates the accounting information,
5915 known as the client, MUST produce the first INTERIM_RECORD record
5916 roughly at the time when this nominal interval has elapsed from
5917 the START_RECORD, the next one again as the interval has elapsed
5918 once more, and so on until the session ends and a STOP_RECORD
5919 record is produced.
5921 The client MUST ensure that the interim record production times
5922 are randomized so that large accounting message storms are not
5923 created either among records or around a common service start
5924 time.
5926 9.8.3. Accounting-Record-Number AVP
5928 The Accounting-Record-Number AVP (AVP Code 485) is of type Unsigned32
5929 and identifies this record within one session. As Session-Id AVPs
5930 are globally unique, the combination of Session-Id and Accounting-
5931 Record-Number AVPs is also globally unique, and can be used in
5932 matching accounting records with confirmations. An easy way to
5933 produce unique numbers is to set the value to 0 for records of type
5934 EVENT_RECORD and START_RECORD, and set the value to 1 for the first
5935 INTERIM_RECORD, 2 for the second, and so on until the value for
5936 STOP_RECORD is one more than for the last INTERIM_RECORD.
5938 9.8.4. Acct-Session-Id AVP
5940 The Acct-Session-Id AVP (AVP Code 44) is of type OctetString is only
5941 used when RADIUS/Diameter translation occurs. This AVP contains the
5942 contents of the RADIUS Acct-Session-Id attribute.
5944 9.8.5. Acct-Multi-Session-Id AVP
5946 The Acct-Multi-Session-Id AVP (AVP Code 50) is of type UTF8String,
5947 following the format specified in Section 8.8. The Acct-Multi-
5948 Session-Id AVP is used to link together multiple related accounting
5949 sessions, where each session would have a unique Session-Id, but the
5950 same Acct-Multi-Session-Id AVP. This AVP MAY be returned by the
5951 Diameter server in an authorization answer, and MUST be used in all
5952 accounting messages for the given session.
5954 9.8.6. Accounting-Sub-Session-Id AVP
5956 The Accounting-Sub-Session-Id AVP (AVP Code 287) is of type
5957 Unsigned64 and contains the accounting sub-session identifier. The
5958 combination of the Session-Id and this AVP MUST be unique per sub-
5959 session, and the value of this AVP MUST be monotonically increased by
5960 one for all new sub-sessions. The absence of this AVP implies no
5961 sub-sessions are in use, with the exception of an Accounting-Request
5962 whose Accounting-Record-Type is set to STOP_RECORD. A STOP_RECORD
5963 message with no Accounting-Sub-Session-Id AVP present will signal the
5964 termination of all sub-sessions for a given Session-Id.
5966 9.8.7. Accounting-Realtime-Required AVP
5968 The Accounting-Realtime-Required AVP (AVP Code 483) is of type
5969 Enumerated and is sent from the Diameter home authorization server to
5970 the Diameter client or in the Accounting-Answer from the accounting
5971 server. The client uses information in this AVP to decide what to do
5972 if the sending of accounting records to the accounting server has
5973 been temporarily prevented due to, for instance, a network problem.
5975 DELIVER_AND_GRANT 1
5977 The AVP with Value field set to DELIVER_AND_GRANT means that the
5978 service MUST only be granted as long as there is a connection to
5979 an accounting server. Note that the set of alternative accounting
5980 servers are treated as one server in this sense. Having to move
5981 the accounting record stream to a backup server is not a reason to
5982 discontinue the service to the user.
5984 GRANT_AND_STORE 2
5986 The AVP with Value field set to GRANT_AND_STORE means that service
5987 SHOULD be granted if there is a connection, or as long as records
5988 can still be stored as described in Section 9.4.
5990 This is the default behavior if the AVP isn't included in the
5991 reply from the authorization server.
5993 GRANT_AND_LOSE 3
5995 The AVP with Value field set to GRANT_AND_LOSE means that service
5996 SHOULD be granted even if the records can not be delivered or
5997 stored.
5999 10. AVP Occurrence Table
6001 The following tables presents the AVPs defined in this document, and
6002 specifies in which Diameter messages they MAY be present or not.
6003 AVPs that occur only inside a Grouped AVP are not shown in this
6004 table.
6006 The table uses the following symbols:
6008 0 The AVP MUST NOT be present in the message.
6010 0+ Zero or more instances of the AVP MAY be present in the
6011 message.
6013 0-1 Zero or one instance of the AVP MAY be present in the message.
6014 It is considered an error if there are more than one instance of
6015 the AVP.
6017 1 One instance of the AVP MUST be present in the message.
6019 1+ At least one instance of the AVP MUST be present in the
6020 message.
6022 10.1. Base Protocol Command AVP Table
6024 The table in this section is limited to the non-accounting Command
6025 Codes defined in this specification.
6027 +-----------------------------------------------+
6028 | Command-Code |
6029 +---+---+---+---+---+---+---+---+---+---+---+---+
6030 Attribute Name |CER|CEA|DPR|DPA|DWR|DWA|RAR|RAA|ASR|ASA|STR|STA|
6031 --------------------+---+---+---+---+---+---+---+---+---+---+---+---+
6032 Acct-Interim- |0 |0 |0 |0 |0 |0 |0-1|0 |0 |0 |0 |0 |
6033 Interval | | | | | | | | | | | | |
6034 Accounting-Realtime-|0 |0 |0 |0 |0 |0 |0-1|0 |0 |0 |0 |0 |
6035 Required | | | | | | | | | | | | |
6036 Acct-Application-Id |0+ |0+ |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6037 Auth-Application-Id |0+ |0+ |0 |0 |0 |0 |1 |0 |1 |0 |1 |0 |
6038 Auth-Grace-Period |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6039 Auth-Request-Type |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6040 Auth-Session-State |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6041 Authorization- |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6042 Lifetime | | | | | | | | | | | | |
6043 Class |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0+ |0+ |
6044 Destination-Host |0 |0 |0 |0 |0 |0 |1 |0 |1 |0 |0-1|0 |
6045 Destination-Realm |0 |0 |0 |0 |0 |0 |1 |0 |1 |0 |1 |0 |
6046 Disconnect-Cause |0 |0 |1 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6047 Error-Message |0 |0-1|0 |0-1|0 |0-1|0 |0-1|0 |0-1|0 |0-1|
6048 Error-Reporting-Host|0 |0 |0 |0 |0 |0 |0 |0-1|0 |0-1|0 |0-1|
6049 Failed-AVP |0 |0+ |0 |0+ |0 |0+ |0 |0+ |0 |0+ |0 |0+ |
6050 Firmware-Revision |0-1|0-1|0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6051 Host-IP-Address |1+ |1+ |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6052 Inband-Security-Id |0+ |0+ |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6053 Multi-Round-Time-Out|0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6054 Origin-Host |1 |1 |1 |1 |1 |1 |1 |1 |1 |1 |1 |1 |
6055 Origin-Realm |1 |1 |1 |1 |1 |1 |1 |1 |1 |1 |1 |1 |
6056 Origin-State-Id |0-1|0-1|0 |0 |0-1|0-1|0-1|0-1|0-1|0-1|0-1|0-1|
6057 Product-Name |1 |1 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6058 Proxy-Info |0 |0 |0 |0 |0 |0 |0+ |0+ |0+ |0+ |0+ |0+ |
6059 Redirect-Host |0 |0 |0 |0 |0 |0 |0 |0+ |0 |0+ |0 |0+ |
6060 Redirect-Host-Usage |0 |0 |0 |0 |0 |0 |0 |0-1|0 |0-1|0 |0-1|
6061 Redirect-Max-Cache- |0 |0 |0 |0 |0 |0 |0 |0-1|0 |0-1|0 |0-1|
6062 Time | | | | | | | | | | | | |
6063 Result-Code |0 |1 |0 |1 |0 |1 |0 |1 |0 |1 |0 |1 |
6064 Re-Auth-Request-Type|0 |0 |0 |0 |0 |0 |1 |0 |0 |0 |0 |0 |
6065 Route-Record |0 |0 |0 |0 |0 |0 |0+ |0 |0+ |0 |0+ |0 |
6066 Session-Binding |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6067 Session-Id |0 |0 |0 |0 |0 |0 |1 |1 |1 |1 |1 |1 |
6068 Session-Server- |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6069 Failover | | | | | | | | | | | | |
6070 Session-Timeout |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6071 Supported-Vendor-Id |0+ |0+ |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6072 Termination-Cause |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |1 |0 |
6073 User-Name |0 |0 |0 |0 |0 |0 |0-1|0-1|0-1|0-1|0-1|0-1|
6074 Vendor-Id |1 |1 |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6075 Vendor-Specific- |0+ |0+ |0 |0 |0 |0 |0 |0 |0 |0 |0 |0 |
6076 Application-Id | | | | | | | | | | | | |
6077 --------------------+---+---+---+---+---+---+---+---+---+---+---+---+
6079 10.2. Accounting AVP Table
6081 The table in this section is used to represent which AVPs defined in
6082 this document are to be present in the Accounting messages. These
6083 AVP occurrence requirements are guidelines, which may be expanded,
6084 and/or overridden by application-specific requirements in the
6085 Diameter applications documents.
6087 +-----------+
6088 | Command |
6089 | Code |
6090 +-----+-----+
6091 Attribute Name | ACR | ACA |
6092 ------------------------------+-----+-----+
6093 Acct-Interim-Interval | 0-1 | 0-1 |
6094 Acct-Multi-Session-Id | 0-1 | 0-1 |
6095 Accounting-Record-Number | 1 | 1 |
6096 Accounting-Record-Type | 1 | 1 |
6097 Acct-Session-Id | 0-1 | 0-1 |
6098 Accounting-Sub-Session-Id | 0-1 | 0-1 |
6099 Accounting-Realtime-Required | 0-1 | 0-1 |
6100 Acct-Application-Id | 0-1 | 0-1 |
6101 Auth-Application-Id | 0 | 0 |
6102 Class | 0+ | 0+ |
6103 Destination-Host | 0-1 | 0 |
6104 Destination-Realm | 1 | 0 |
6105 Error-Reporting-Host | 0 | 0+ |
6106 Event-Timestamp | 0-1 | 0-1 |
6107 Origin-Host | 1 | 1 |
6108 Origin-Realm | 1 | 1 |
6109 Proxy-Info | 0+ | 0+ |
6110 Route-Record | 0+ | 0 |
6111 Result-Code | 0 | 1 |
6112 Session-Id | 1 | 1 |
6113 Termination-Cause | 0 | 0 |
6114 User-Name | 0-1 | 0-1 |
6115 Vendor-Specific-Application-Id| 0-1 | 0-1 |
6116 ------------------------------+-----+-----+
6118 11. IANA Considerations
6120 This section provides guidance to the Internet Assigned Numbers
6121 Authority (IANA) regarding registration of values related to the
6122 Diameter protocol, in accordance with BCP 26 [RFC2434]. The
6123 following policies are used here with the meanings defined in BCP 26:
6124 "Private Use", "First Come First Served", "Expert Review",
6125 "Specification Required", "IETF Consensus", "Standards Action".
6127 This section explains the criteria to be used by the IANA for
6128 assignment of numbers within namespaces defined within this document.
6130 Diameter is not intended as a general purpose protocol, and
6131 allocations SHOULD NOT be made for purposes unrelated to
6132 authentication, authorization or accounting.
6134 For registration requests where a Designated Expert should be
6135 consulted, the responsible IESG area director should appoint the
6136 Designated Expert. For Designated Expert with Specification
6137 Required, the request is posted to the DIME WG mailing list (or, if
6138 it has been disbanded, a successor designated by the Area Director)
6139 for comment and review, and MUST include a pointer to a public
6140 specification. Before a period of 30 days has passed, the Designated
6141 Expert will either approve or deny the registration request and
6142 publish a notice of the decision to the DIME WG mailing list or its
6143 successor. A denial notice must be justified by an explanation and,
6144 in the cases where it is possible, concrete suggestions on how the
6145 request can be modified so as to become acceptable.
6147 11.1. AVP Header
6149 As defined in Section 4, the AVP header contains three fields that
6150 requires IANA namespace management; the AVP Code, Vendor-ID and Flags
6151 field.
6153 11.1.1. AVP Codes
6155 The AVP Code namespace is used to identify attributes. There are
6156 multiple namespaces. Vendors can have their own AVP Codes namespace
6157 which will be identified by their Vendor-ID (also known as
6158 Enterprise-Number) and they control the assignments of their vendor-
6159 specific AVP codes within their own namespace. The absence of a
6160 Vendor-ID or a Vendor-ID value of zero (0) identifies the IETF IANA
6161 controlled AVP Codes namespace. The AVP Codes and sometimes also
6162 possible values in an AVP are controlled and maintained by IANA.
6164 AVP Code 0 is not used. AVP Codes 1-255 are managed separately as
6165 RADIUS Attribute Types [RADTYPE]. This document defines the AVP
6166 Codes 257-274, 276-285, 287, 291-300, 480, 483 and 485-486. See
6167 Section 4.5 for the assignment of the namespace in this
6168 specification.
6170 AVPs may be allocated following Designated Expert with Specification
6171 Required [RFC2434]. Release of blocks of AVPs (more than 3 at a time
6172 for a given purpose) should require IETF Consensus.
6174 Note that Diameter defines a mechanism for Vendor-Specific AVPs,
6175 where the Vendor-Id field in the AVP header is set to a non-zero
6176 value. Vendor-Specific AVPs codes are for Private Use and should be
6177 encouraged instead of allocation of global attribute types, for
6178 functions specific only to one vendor's implementation of Diameter,
6179 where no interoperability is deemed useful. Where a Vendor-Specific
6180 AVP is implemented by more than one vendor, allocation of global AVPs
6181 should be encouraged instead.
6183 11.1.2. AVP Flags
6185 There are 8 bits in the AVP Flags field of the AVP header, defined in
6186 Section 4. This document assigns bit 0 ('V'endor Specific), bit 1
6187 ('M'andatory) and bit 2 ('P'rotected). The remaining bits should
6188 only be assigned via a Standards Action [RFC2434].
6190 11.2. Diameter Header
6192 As defined in Section 3, the Diameter header contains two fields that
6193 require IANA namespace management; Command Code and Command Flags.
6195 11.2.1. Command Codes
6197 The Command Code namespace is used to identify Diameter commands.
6198 The values 0-255 (0x00-0xff) are reserved for RADIUS backward
6199 compatibility, and are defined as "RADIUS Packet Type Codes" in
6200 [RADTYPE]. Values 256 - 8,388,607 (0x100 to 0x7fffff) are for
6201 permanent, standard commands, allocated by IETF Consensus [RFC2434].
6202 This document defines the Command Codes 257, 258, 271, 274-275, 280
6203 and 282. See Section 3.1 for the assignment of the namespace in this
6204 specification.
6206 The values 8,388,608 - 16,777,213 (0x800000 - 0xfffffd) are reserved
6207 for vendor-specific command codes, to be allocated on a First Come,
6208 First Served basis by IANA [RFC2434]. The request to IANA for a
6209 Vendor-Specific Command Code SHOULD include a reference to a publicly
6210 available specification which documents the command in sufficient
6211 detail to aid in interoperability between independent
6212 implementations. If the specification cannot be made publicly
6213 available, the request for a vendor-specific command code MUST
6214 include the contact information of persons and/or entities
6215 responsible for authoring and maintaining the command.
6217 The values 16,777,214 and 16,777,215 (hexadecimal values 0xfffffe -
6218 0xffffff) are reserved for experimental commands. As these codes are
6219 only for experimental and testing purposes, no guarantee is made for
6220 interoperability between Diameter peers using experimental commands,
6221 as outlined in [IANA-EXP].
6223 11.2.2. Command Flags
6225 There are eight bits in the Command Flags field of the Diameter
6226 header. This document assigns bit 0 ('R'equest), bit 1 ('P'roxy),
6227 bit 2 ('E'rror) and bit 3 ('T'). Bits 4 through 7 MUST only be
6228 assigned via a Standards Action [RFC2434].
6230 11.3. Application Identifiers
6232 As defined in Section 2.4, the Application Identifier is used to
6233 identify a specific Diameter Application. There are standards-track
6234 application ids and vendor specific application ids.
6236 IANA [RFC2434] has assigned the range 0x00000001 to 0x00ffffff for
6237 standards-track applications; and 0x01000000 - 0xfffffffe for vendor
6238 specific applications, on a first-come, first-served basis. The
6239 following values are allocated.
6241 Diameter Common Messages 0
6242 NASREQ 1 [RFC4005]
6243 Mobile-IP 2 [RFC4004]
6244 Diameter Base Accounting 3
6245 Relay 0xffffffff
6247 Assignment of standards-track application IDs are by Designated
6248 Expert with Specification Required [RFC2434].
6250 Both Auth-Application-Id and Acct-Application-Id AVPs use the same
6251 Application Identifier space. A diameter node advertising itself as
6252 a relay agent MUST set either Application-Id or Acct-Application-Id
6253 to 0xffffffff.
6255 Vendor-Specific Application Identifiers, are for Private Use. Vendor-
6256 Specific Application Identifiers are assigned on a First Come, First
6257 Served basis by IANA.
6259 11.4. AVP Values
6261 Certain AVPs in Diameter define a list of values with various
6262 meanings. For attributes other than those specified in this section,
6263 adding additional values to the list can be done on a First Come,
6264 First Served basis by IANA.
6266 11.4.1. Result-Code AVP Values
6268 As defined in Section 7.1, the Result-Code AVP (AVP Code 268) defines
6269 the values 1001, 2001-2002, 3001-3012, 4001-4003 and 5001-5021.
6271 All remaining values are available for assignment via IETF Consensus
6272 [RFC2434].
6274 11.4.2. Accounting-Record-Type AVP Values
6276 As defined in Section 9.8.1, the Accounting-Record-Type AVP (AVP Code
6277 480) defines the values 1-4. All remaining values are available for
6278 assignment via IETF Consensus [RFC2434].
6280 11.4.3. Termination-Cause AVP Values
6282 As defined in Section 8.15, the Termination-Cause AVP (AVP Code 295)
6283 defines the values 1-8. All remaining values are available for
6284 assignment via IETF Consensus [RFC2434].
6286 11.4.4. Redirect-Host-Usage AVP Values
6288 As defined in Section 6.13, the Redirect-Host-Usage AVP (AVP Code
6289 261) defines the values 0-5. All remaining values are available for
6290 assignment via IETF Consensus [RFC2434].
6292 11.4.5. Session-Server-Failover AVP Values
6294 As defined in Section 8.18, the Session-Server-Failover AVP (AVP Code
6295 271) defines the values 0-3. All remaining values are available for
6296 assignment via IETF Consensus [RFC2434].
6298 11.4.6. Session-Binding AVP Values
6300 As defined in Section 8.17, the Session-Binding AVP (AVP Code 270)
6301 defines the bits 1-4. All remaining bits are available for
6302 assignment via IETF Consensus [RFC2434].
6304 11.4.7. Disconnect-Cause AVP Values
6306 As defined in Section 5.4.3, the Disconnect-Cause AVP (AVP Code 273)
6307 defines the values 0-2. All remaining values are available for
6308 assignment via IETF Consensus [RFC2434].
6310 11.4.8. Auth-Request-Type AVP Values
6312 As defined in Section 8.7, the Auth-Request-Type AVP (AVP Code 274)
6313 defines the values 1-3. All remaining values are available for
6314 assignment via IETF Consensus [RFC2434].
6316 11.4.9. Auth-Session-State AVP Values
6318 As defined in Section 8.11, the Auth-Session-State AVP (AVP Code 277)
6319 defines the values 0-1. All remaining values are available for
6320 assignment via IETF Consensus [RFC2434].
6322 11.4.10. Re-Auth-Request-Type AVP Values
6324 As defined in Section 8.12, the Re-Auth-Request-Type AVP (AVP Code
6325 285) defines the values 0-1. All remaining values are available for
6326 assignment via IETF Consensus [RFC2434].
6328 11.4.11. Accounting-Realtime-Required AVP Values
6330 As defined in Section 9.8.7, the Accounting-Realtime-Required AVP
6331 (AVP Code 483) defines the values 1-3. All remaining values are
6332 available for assignment via IETF Consensus [RFC2434].
6334 11.4.12. Inband-Security-Id AVP (code 299)
6336 As defined in Section 6.10, the Inband-Security-Id AVP (AVP Code 299)
6337 defines the values 0-1. All remaining values are available for
6338 assignment via IETF Consensus [RFC2434].
6340 11.5. Diameter TCP/SCTP Port Numbers
6342 The IANA has assigned TCP and SCTP port number 3868 to Diameter.
6344 11.6. NAPTR Service Fields
6346 The registration in the RFC MUST include the following information:
6348 Service Field: The service field being registered. An example for a
6349 new fictitious transport protocol called NCTP might be "AAA+D2N".
6351 Protocol: The specific transport protocol associated with that
6352 service field. This MUST include the name and acronym for the
6353 protocol, along with reference to a document that describes the
6354 transport protocol. For example - "New Connectionless Transport
6355 Protocol (NCTP), RFC 5766".
6357 Name and Contact Information: The name, address, email address and
6358 telephone number for the person performing the registration.
6360 The following values have been placed into the registry:
6362 Services Field Protocol
6364 AAA+D2T TCP
6365 AAA+D2S SCTP
6367 12. Diameter protocol related configurable parameters
6369 This section contains the configurable parameters that are found
6370 throughout this document:
6372 Diameter Peer
6374 A Diameter entity MAY communicate with peers that are statically
6375 configured. A statically configured Diameter peer would require
6376 that either the IP address or the fully qualified domain name
6377 (FQDN) be supplied, which would then be used to resolve through
6378 DNS.
6380 Routing Table
6382 A Diameter proxy server routes messages based on the realm portion
6383 of a Network Access Identifier (NAI). The server MUST have a
6384 table of Realm Names, and the address of the peer to which the
6385 message must be forwarded to. The routing table MAY also include
6386 a "default route", which is typically used for all messages that
6387 cannot be locally processed.
6389 Tc timer
6391 The Tc timer controls the frequency that transport connection
6392 attempts are done to a peer with whom no active transport
6393 connection exists. The recommended value is 30 seconds.
6395 13. Security Considerations
6397 The Diameter base protocol assumes that messages maybe secured by
6398 using TLS. As an alternative, IPSec can be also be used to secure
6399 Diameter peer connections but its usage is transparent from the
6400 Diameter node and Diameter protocol perspective. These security
6401 mechanism is acceptable in environments where there is no untrusted
6402 third party agent.
6404 Diameter clients, such as Network Access Servers (NASes) and Mobility
6405 Agents MAY support TLS [RFC4346]. Diameter servers MUST support TLS.
6406 Diameter implementations SHOULD use transmission-level security of
6407 some kind (IPsec or TLS) on each connection.
6409 If a Diameter connection is to be protected via TLS, then the CER/CEA
6410 exchange MUST include an Inband-Security-ID AVP with a value of TLS.
6411 For TLS usage, a TLS handshake will begin when both ends are in the
6412 open state, after completion of the CER/CEA exchange. If the TLS
6413 handshake is successful, all further messages will be sent via TLS.
6414 If the handshake fails, both ends move to the closed state. See
6415 Sections 13.1 for more details.
6417 13.1. TLS Usage
6419 A Diameter node that initiates a connection to another Diameter node
6420 acts as a TLS client according to [RFC4346], and a Diameter node that
6421 accepts a connection acts as a TLS server. Diameter nodes
6422 implementing TLS for security MUST mutually authenticate as part of
6423 TLS session establishment. In order to ensure mutual authentication,
6424 the Diameter node acting as TLS server must request a certificate
6425 from the Diameter node acting as TLS client, and the Diameter node
6426 acting as TLS client MUST be prepared to supply a certificate on
6427 request.
6429 Diameter nodes MUST be able to negotiate the following TLS cipher
6430 suites:
6432 TLS_RSA_WITH_RC4_128_MD5
6433 TLS_RSA_WITH_RC4_128_SHA
6434 TLS_RSA_WITH_3DES_EDE_CBC_SHA
6436 Diameter nodes SHOULD be able to negotiate the following TLS cipher
6437 suite:
6439 TLS_RSA_WITH_AES_128_CBC_SHA
6441 Diameter nodes MAY negotiate other TLS cipher suites.
6443 13.2. Peer-to-Peer Considerations
6445 As with any peer-to-peer protocol, proper configuration of the trust
6446 model within a Diameter peer is essential to security. When
6447 certificates are used, it is necessary to configure the root
6448 certificate authorities trusted by the Diameter peer. These root CAs
6449 are likely to be unique to Diameter usage and distinct from the root
6450 CAs that might be trusted for other purposes such as Web browsing.
6451 In general, it is expected that those root CAs will be configured so
6452 as to reflect the business relationships between the organization
6453 hosting the Diameter peer and other organizations. As a result, a
6454 Diameter peer will typically not be configured to allow connectivity
6455 with any arbitrary peer. With certificate authentication, Diameter
6456 peers may not be known beforehand and therefore peer discovery may be
6457 required.
6459 14. References
6461 14.1. Normative References
6463 [FLOATPOINT]
6464 Institute of Electrical and Electronics Engineers, "IEEE
6465 Standard for Binary Floating-Point Arithmetic, ANSI/IEEE
6466 Standard 754-1985", August 1985.
6468 [IANAADFAM]
6469 IANA,, "Address Family Numbers",
6470 http://www.iana.org/assignments/address-family-numbers.
6472 [RADTYPE] IANA,, "RADIUS Types",
6473 http://www.iana.org/assignments/radius-types.
6475 [IPV4] Postel, J., "Internet Protocol", RFC 791, September 1981.
6477 [TCP] Postel, J., "Transmission Control Protocol", RFC 793,
6478 January 1981.
6480 [RFC3539] Aboba, B. and J. Wood, "Authentication, Authorization and
6481 Accounting (AAA) Transport Profile", RFC 3539, June 2003.
6483 [RFC4004] Calhoun, P., Johansson, T., Perkins, C., Hiller, T., and
6484 P. McCann, "Diameter Mobile IPv4 Application", RFC 4004,
6485 August 2005.
6487 [RFC4005] Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
6488 "Diameter Network Access Server Application", RFC 4005,
6489 August 2005.
6491 [RFC4006] Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J.
6492 Loughney, "Diameter Credit-Control Application", RFC 4006,
6493 August 2005.
6495 [RFC4072] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible
6496 Authentication Protocol (EAP) Application", RFC 4072,
6497 August 2005.
6499 [RFC4740] Garcia-Martin, M., Belinchon, M., Pallares-Lopez, M.,
6500 Canales-Valenzuela, C., and K. Tammi, "Diameter Session
6501 Initiation Protocol (SIP) Application", RFC 4740,
6502 November 2006.
6504 [RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
6505 Specifications: ABNF", RFC 4234, October 2005.
6507 [RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
6508 Arkko, "Diameter Base Protocol", RFC 3588, September 2003.
6510 [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
6511 Levkowetz, "Extensible Authentication Protocol (EAP)",
6512 RFC 3748, June 2004.
6514 [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
6515 IANA Considerations Section in RFCs", BCP 26, RFC 2434,
6516 October 1998.
6518 [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
6519 RFC 4306, December 2005.
6521 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
6522 Architecture", RFC 4291, February 2006.
6524 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
6525 Requirement Levels", BCP 14, RFC 2119, March 1997.
6527 [RFC4282] Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The
6528 Network Access Identifier", RFC 4282, December 2005.
6530 [RFC3403] Mealling, M., "Dynamic Delegation Discovery System (DDDS)
6531 Part Three: The Domain Name System (DNS) Database",
6532 RFC 3403, October 2002.
6534 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
6535 A., Peterson, J., Sparks, R., Handley, M., and E.
6536 Schooler, "SIP: Session Initiation Protocol", RFC 3261,
6537 June 2002.
6539 [RFC2960] Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
6540 Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M.,
6541 Zhang, L., and V. Paxson, "Stream Control Transmission
6542 Protocol", RFC 2960, October 2000.
6544 [RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
6545 (TLS) Protocol Version 1.1", RFC 4346, April 2006.
6547 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
6548 Resource Identifier (URI): Generic Syntax", STD 66,
6549 RFC 3986, January 2005.
6551 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
6552 10646", STD 63, RFC 3629, November 2003.
6554 14.2. Informational References
6556 [RFC2989] Aboba, B., Calhoun, P., Glass, S., Hiller, T., McCann, P.,
6557 Shiino, H., Zorn, G., Dommety, G., C.Perkins, B.Patil,
6558 D.Mitton, S.Manning, M.Beadles, P.Walsh, X.Chen,
6559 S.Sivalingham, A.Hameed, M.Munson, S.Jacobs, B.Lim,
6560 B.Hirschman, R.Hsu, Y.Xu, E.Campell, S.Baba, and E.Jaques,
6561 "Criteria for Evaluating AAA Protocols for Network
6562 Access", RFC 2989, November 2000.
6564 [RFC2975] Aboba, B., Arkko, J., and D. Harrington, "Introduction to
6565 Accounting Management", RFC 2975, October 2000.
6567 [RFC3232] Reynolds, J., "Assigned Numbers: RFC 1700 is Replaced by
6568 an On-line Database", RFC 3232, January 2002.
6570 [RFC3576] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
6571 Aboba, "Dynamic Authorization Extensions to Remote
6572 Authentication Dial In User Service (RADIUS)", RFC 3576,
6573 July 2003.
6575 [RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,
6576 RFC 1661, July 1994.
6578 [RFC2607] Aboba, B. and J. Vollbrecht, "Proxy Chaining and Policy
6579 Implementation in Roaming", RFC 2607, June 1999.
6581 [RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.
6583 [RFC2869] Rigney, C., Willats, W., and P. Calhoun, "RADIUS
6584 Extensions", RFC 2869, June 2000.
6586 [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
6587 "Remote Authentication Dial In User Service (RADIUS)",
6588 RFC 2865, June 2000.
6590 [RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6",
6591 RFC 3162, August 2001.
6593 [RFC2194] Aboba, B., Lu, J., Alsop, J., Ding, J., and W. Wang,
6594 "Review of Roaming Implementations", RFC 2194,
6595 September 1997.
6597 [RFC2477] Aboba, B. and G. Zorn, "Criteria for Evaluating Roaming
6598 Protocols", RFC 2477, January 1999.
6600 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
6601 Internet Protocol", RFC 4301, December 2005.
6603 [RFC4330] Mills, D., "Simple Network Time Protocol (SNTP) Version 4
6604 for IPv4, IPv6 and OSI", RFC 4330, January 2006.
6606 [RFC1492] Finseth, C., "An Access Control Protocol, Sometimes Called
6607 TACACS", RFC 1492, July 1993.
6609 [IANA-EXP]
6610 Narten, T., "Assigning Experimental and Testing Numbers
6611 Considered Useful, Work in Progress.".
6613 Appendix A. Acknowledgements
6615 The authors would like to thank the following people that have
6616 provided proposals and contributions to this document:
6618 To Vishnu Ram and Satendra Gera for their contributions on
6619 Capabilities Updates, Predictive Loop Avoidance as well as many other
6620 technical proposals. To Tolga Asveren for his insights and
6621 contributions on almost all of the proposed solutions incorporated
6622 into this document. To Timothy Smith for helping on the Capabilities
6623 Updates and other topics. To Tony Zhang for providing fixes to loop
6624 holes on composing Failed-AVPs as well as many other issues and
6625 topics. To Jan Nordqvist for clearly stating the usage of
6626 application ids. To Anders Kristensen for providing needed technical
6627 opinions. To David Frascone for providing invaluable review of the
6628 document. To Mark Jones for providing clarifying text on vendor
6629 command codes and other vendor specific indicators.
6631 Special thanks also to people who have provided invaluable comments
6632 and inputs especially in resolving controversial issues:
6634 Glen Zorn, Yoshihiro Ohba, Marco Stura, and Pasi Eronen.
6636 Finally, we would like to thank the original authors of this
6637 document:
6639 Pat Calhoun, John Loughney, Jari Arkko, Erik Guttman and Glen Zorn.
6641 Their invaluable knowledge and experience has given us a robust and
6642 flexible AAA protocol that many people have seen great value in
6643 adopting. We greatly appreciate their support and stewardship for
6644 the continued improvements of Diameter as a protocol. We would also
6645 like to extend our gratitude to folks aside from the authors who have
6646 assisted and contributed to the original version of this document.
6647 Their efforts significantly contributed to the success of Diameter.
6649 Appendix B. NAPTR Example
6651 As an example, consider a client that wishes to resolve aaa:ex.com.
6652 The client performs a NAPTR query for that domain, and the following
6653 NAPTR records are returned:
6655 ;; order pref flags service regexp replacement
6656 IN NAPTR 50 50 "s" "AAA+D2S" ""
6657 _diameter._sctp.example.com IN NAPTR 100 50 "s" "AAA+D2T"
6658 "" _aaa._tcp.example.com
6660 This indicates that the server supports SCTP, and TCP, in that order.
6661 If the client supports over SCTP, SCTP will be used, targeted to a
6662 host determined by an SRV lookup of _diameter._sctp.ex.com. That
6663 lookup would return:
6665 ;; Priority Weight Port Target
6666 IN SRV 0 1 5060 server1.example.com IN SRV 0
6667 2 5060 server2.example.com
6669 Appendix C. Duplicate Detection
6671 As described in Section 9.4, accounting record duplicate detection is
6672 based on session identifiers. Duplicates can appear for various
6673 reasons:
6675 o Failover to an alternate server. Where close to real-time
6676 performance is required, failover thresholds need to be kept low
6677 and this may lead to an increased likelihood of duplicates.
6678 Failover can occur at the client or within Diameter agents.
6680 o Failure of a client or agent after sending of a record from non-
6681 volatile memory, but prior to receipt of an application layer ACK
6682 and deletion of the record. record to be sent. This will result
6683 in retransmission of the record soon after the client or agent has
6684 rebooted.
6686 o Duplicates received from RADIUS gateways. Since the
6687 retransmission behavior of RADIUS is not defined within [RFC2865],
6688 the likelihood of duplication will vary according to the
6689 implementation.
6691 o Implementation problems and misconfiguration.
6693 The T flag is used as an indication of an application layer
6694 retransmission event, e.g., due to failover to an alternate server.
6695 It is defined only for request messages sent by Diameter clients or
6696 agents. For instance, after a reboot, a client may not know whether
6697 it has already tried to send the accounting records in its non-
6698 volatile memory before the reboot occurred. Diameter servers MAY use
6699 the T flag as an aid when processing requests and detecting duplicate
6700 messages. However, servers that do this MUST ensure that duplicates
6701 are found even when the first transmitted request arrives at the
6702 server after the retransmitted request. It can be used only in cases
6703 where no answer has been received from the Server for a request and
6704 the request is sent again, (e.g., due to a failover to an alternate
6705 peer, due to a recovered primary peer or due to a client re-sending a
6706 stored record from non-volatile memory such as after reboot of a
6707 client or agent).
6709 In some cases the Diameter accounting server can delay the duplicate
6710 detection and accounting record processing until a post-processing
6711 phase takes place. At that time records are likely to be sorted
6712 according to the included User-Name and duplicate elimination is easy
6713 in this case. In other situations it may be necessary to perform
6714 real-time duplicate detection, such as when credit limits are imposed
6715 or real-time fraud detection is desired.
6717 In general, only generation of duplicates due to failover or re-
6718 sending of records in non-volatile storage can be reliably detected
6719 by Diameter clients or agents. In such cases the Diameter client or
6720 agents can mark the message as possible duplicate by setting the T
6721 flag. Since the Diameter server is responsible for duplicate
6722 detection, it can choose to make use of the T flag or not, in order
6723 to optimize duplicate detection. Since the T flag does not affect
6724 interoperability, and may not be needed by some servers, generation
6725 of the T flag is REQUIRED for Diameter clients and agents, but MAY be
6726 implemented by Diameter servers.
6728 As an example, it can be usually be assumed that duplicates appear
6729 within a time window of longest recorded network partition or device
6730 fault, perhaps a day. So only records within this time window need
6731 to be looked at in the backward direction. Secondly, hashing
6732 techniques or other schemes, such as the use of the T flag in the
6733 received messages, may be used to eliminate the need to do a full
6734 search even in this set except for rare cases.
6736 The following is an example of how the T flag may be used by the
6737 server to detect duplicate requests.
6739 A Diameter server MAY check the T flag of the received message to
6740 determine if the record is a possible duplicate. If the T flag is
6741 set in the request message, the server searches for a duplicate
6742 within a configurable duplication time window backward and
6743 forward. This limits database searching to those records where
6744 the T flag is set. In a well run network, network partitions and
6745 device faults will presumably be rare events, so this approach
6746 represents a substantial optimization of the duplicate detection
6747 process. During failover, it is possible for the original record
6748 to be received after the T flag marked record, due to differences
6749 in network delays experienced along the path by the original and
6750 duplicate transmissions. The likelihood of this occurring
6751 increases as the failover interval is decreased. In order to be
6752 able to detect out of order duplicates, the Diameter server should
6753 use backward and forward time windows when performing duplicate
6754 checking for the T flag marked request. For example, in order to
6755 allow time for the original record to exit the network and be
6756 recorded by the accounting server, the Diameter server can delay
6757 processing records with the T flag set until a time period
6758 TIME_WAIT + RECORD_PROCESSING_TIME has elapsed after the closing
6759 of the original transport connection. After this time period has
6760 expired, then it may check the T flag marked records against the
6761 database with relative assurance that the original records, if
6762 sent, have been received and recorded.
6764 Authors' Addresses
6766 Victor Fajardo (editor)
6767 Toshiba America Research
6768 One Telcordia Drive, 1S-222
6769 Piscataway, NJ 08854
6770 USA
6772 Phone: 1 908-421-1845
6773 Email: vfajardo@tari.toshiba.com
6775 Jari Arkko
6776 Ericsson Research
6777 02420 Jorvas
6778 Finland
6780 Phone: +358 40 5079256
6781 Email: jari.arkko@ericsson.com
6783 John Loughney
6784 Nokia Research Center
6785 955 Page Mill Road
6786 Palo Alto, CA 94304
6787 US
6789 Phone: 1-650-283-8068
6790 Email: john.loughney@nokia.com
6792 Full Copyright Statement
6794 Copyright (C) The IETF Trust (2007).
6796 This document is subject to the rights, licenses and restrictions
6797 contained in BCP 78, and except as set forth therein, the authors
6798 retain all their rights.
6800 This document and the information contained herein are provided on an
6801 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
6802 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
6803 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
6804 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
6805 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
6806 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
6808 Intellectual Property
6810 The IETF takes no position regarding the validity or scope of any
6811 Intellectual Property Rights or other rights that might be claimed to
6812 pertain to the implementation or use of the technology described in
6813 this document or the extent to which any license under such rights
6814 might or might not be available; nor does it represent that it has
6815 made any independent effort to identify any such rights. Information
6816 on the procedures with respect to rights in RFC documents can be
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6819 Copies of IPR disclosures made to the IETF Secretariat and any
6820 assurances of licenses to be made available, or the result of an
6821 attempt made to obtain a general license or permission for the use of
6822 such proprietary rights by implementers or users of this
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6824 http://www.ietf.org/ipr.
6826 The IETF invites any interested party to bring to its attention any
6827 copyrights, patents or patent applications, or other proprietary
6828 rights that may cover technology that may be required to implement
6829 this standard. Please address the information to the IETF at
6830 ietf-ipr@ietf.org.
6832 Acknowledgment
6834 Funding for the RFC Editor function is provided by the IETF
6835 Administrative Support Activity (IASA).