< draft-ietf-dime-ovli-05.txt   draft-ietf-dime-ovli-06.txt >
Diameter Maintenance and Extensions (DIME) J. Korhonen, Ed. Diameter Maintenance and Extensions (DIME) J. Korhonen, Ed.
Internet-Draft Broadcom Internet-Draft Broadcom
Intended status: Standards Track S. Donovan, Ed. Intended status: Standards Track S. Donovan, Ed.
Expires: June 6, 2015 B. Campbell Expires: July 12, 2015 B. Campbell
Oracle Oracle
L. Morand L. Morand
Orange Labs Orange Labs
December 3, 2014 January 8, 2015
Diameter Overload Indication Conveyance Diameter Overload Indication Conveyance
draft-ietf-dime-ovli-05.txt draft-ietf-dime-ovli-06.txt
Abstract Abstract
This specification defines a base solution for Diameter overload This specification defines a base solution for Diameter overload
control, referred to as Diameter Overload Indication Conveyance control, referred to as Diameter Overload Indication Conveyance
(DOIC). (DOIC).
Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 6, 2015. This Internet-Draft will expire on July 12, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Abbreviations . . . . . . . . . . . . . . . . 4 2. Terminology and Abbreviations . . . . . . . . . . . . . . . . 4
3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 5 3. Conventions Used in This Document . . . . . . . . . . . . . . 5
3.1. Piggybacking . . . . . . . . . . . . . . . . . . . . . . 7 4. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 5
3.2. DOIC Capability Announcement . . . . . . . . . . . . . . 8 4.1. Piggybacking . . . . . . . . . . . . . . . . . . . . . . 7
3.3. DOIC Overload Condition Reporting . . . . . . . . . . . . 9 4.2. DOIC Capability Announcement . . . . . . . . . . . . . . 7
3.4. DOIC Extensibility . . . . . . . . . . . . . . . . . . . 11 4.3. DOIC Overload Condition Reporting . . . . . . . . . . . . 9
3.5. Simplified Example Architecture . . . . . . . . . . . . . 12 4.4. DOIC Extensibility . . . . . . . . . . . . . . . . . . . 11
4. Solution Procedures . . . . . . . . . . . . . . . . . . . . . 12 4.5. Simplified Example Architecture . . . . . . . . . . . . . 11
4.1. Capability Announcement . . . . . . . . . . . . . . . . . 12 5. Solution Procedures . . . . . . . . . . . . . . . . . . . . . 12
4.1.1. Reacting Node Behavior . . . . . . . . . . . . . . . 13 5.1. Capability Announcement . . . . . . . . . . . . . . . . . 12
4.1.2. Reporting Node Behavior . . . . . . . . . . . . . . . 13 5.1.1. Reacting Node Behavior . . . . . . . . . . . . . . . 13
4.1.3. Agent Behavior . . . . . . . . . . . . . . . . . . . 14 5.1.2. Reporting Node Behavior . . . . . . . . . . . . . . . 13
4.2. Overload Report Processing . . . . . . . . . . . . . . . 15 5.1.3. Agent Behavior . . . . . . . . . . . . . . . . . . . 14
4.2.1. Overload Control State . . . . . . . . . . . . . . . 15 5.2. Overload Report Processing . . . . . . . . . . . . . . . 15
4.2.2. Reacting Node Behavior . . . . . . . . . . . . . . . 19 5.2.1. Overload Control State . . . . . . . . . . . . . . . 15
4.2.3. Reporting Node Behavior . . . . . . . . . . . . . . . 20 5.2.2. Reacting Node Behavior . . . . . . . . . . . . . . . 19
4.3. Protocol Extensibility . . . . . . . . . . . . . . . . . 21 5.2.3. Reporting Node Behavior . . . . . . . . . . . . . . . 20
5. Loss Algorithm . . . . . . . . . . . . . . . . . . . . . . . 22 5.3. Protocol Extensibility . . . . . . . . . . . . . . . . . 21
5.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 22 6. Loss Algorithm . . . . . . . . . . . . . . . . . . . . . . . 22
5.2. Reporting Node Behavior . . . . . . . . . . . . . . . . . 23 6.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 22
5.3. Reacting Node Behavior . . . . . . . . . . . . . . . . . 24 6.2. Reporting Node Behavior . . . . . . . . . . . . . . . . . 23
6. Attribute Value Pairs . . . . . . . . . . . . . . . . . . . . 25 6.3. Reacting Node Behavior . . . . . . . . . . . . . . . . . 24
6.1. OC-Supported-Features AVP . . . . . . . . . . . . . . . . 25 7. Attribute Value Pairs . . . . . . . . . . . . . . . . . . . . 24
6.2. OC-Feature-Vector AVP . . . . . . . . . . . . . . . . . . 25 7.1. OC-Supported-Features AVP . . . . . . . . . . . . . . . . 25
6.3. OC-OLR AVP . . . . . . . . . . . . . . . . . . . . . . . 26 7.2. OC-Feature-Vector AVP . . . . . . . . . . . . . . . . . . 25
6.4. OC-Sequence-Number AVP . . . . . . . . . . . . . . . . . 26 7.3. OC-OLR AVP . . . . . . . . . . . . . . . . . . . . . . . 25
6.5. OC-Validity-Duration AVP . . . . . . . . . . . . . . . . 27 7.4. OC-Sequence-Number AVP . . . . . . . . . . . . . . . . . 26
6.6. OC-Report-Type AVP . . . . . . . . . . . . . . . . . . . 27 7.5. OC-Validity-Duration AVP . . . . . . . . . . . . . . . . 26
6.7. OC-Reduction-Percentage AVP . . . . . . . . . . . . . . . 27 7.6. OC-Report-Type AVP . . . . . . . . . . . . . . . . . . . 26
6.8. Attribute Value Pair flag rules . . . . . . . . . . . . . 27 7.7. OC-Reduction-Percentage AVP . . . . . . . . . . . . . . . 27
7. Error Response Codes . . . . . . . . . . . . . . . . . . . . 28 7.8. Attribute Value Pair flag rules . . . . . . . . . . . . . 27
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 8. Error Response Codes . . . . . . . . . . . . . . . . . . . . 28
8.1. AVP codes . . . . . . . . . . . . . . . . . . . . . . . . 29 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
8.2. New registries . . . . . . . . . . . . . . . . . . . . . 29 9.1. AVP codes . . . . . . . . . . . . . . . . . . . . . . . . 28
9. Security Considerations . . . . . . . . . . . . . . . . . . . 30 9.2. New registries . . . . . . . . . . . . . . . . . . . . . 28
9.1. Potential Threat Modes . . . . . . . . . . . . . . . . . 30 10. Security Considerations . . . . . . . . . . . . . . . . . . . 29
9.2. Denial of Service Attacks . . . . . . . . . . . . . . . . 31 10.1. Potential Threat Modes . . . . . . . . . . . . . . . . . 29
9.3. Non-Compliant Nodes . . . . . . . . . . . . . . . . . . . 32 10.2. Denial of Service Attacks . . . . . . . . . . . . . . . 31
9.4. End-to End-Security Issues . . . . . . . . . . . . . . . 32 10.3. Non-Compliant Nodes . . . . . . . . . . . . . . . . . . 31
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 33 10.4. End-to End-Security Issues . . . . . . . . . . . . . . . 31
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 34 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 33
11.1. Normative References . . . . . . . . . . . . . . . . . . 34 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 33
11.2. Informative References . . . . . . . . . . . . . . . . . 34 12.1. Normative References . . . . . . . . . . . . . . . . . . 33
12.2. Informative References . . . . . . . . . . . . . . . . . 33
Appendix A. Issues left for future specifications . . . . . . . 34 Appendix A. Issues left for future specifications . . . . . . . 34
A.1. Additional traffic abatement algorithms . . . . . . . . . 35 A.1. Additional traffic abatement algorithms . . . . . . . . . 34
A.2. Agent Overload . . . . . . . . . . . . . . . . . . . . . 35 A.2. Agent Overload . . . . . . . . . . . . . . . . . . . . . 34
A.3. New Error Diagnostic AVP . . . . . . . . . . . . . . . . 35 A.3. New Error Diagnostic AVP . . . . . . . . . . . . . . . . 34
Appendix B. Deployment Considerations . . . . . . . . . . . . . 35 Appendix B. Deployment Considerations . . . . . . . . . . . . . 34
Appendix C. Requirements Conformance Analysis . . . . . . . . . 35 Appendix C. Requirements Conformance Analysis . . . . . . . . . 35
C.1. Deferred Requirements . . . . . . . . . . . . . . . . . . 36 C.1. Deferred Requirements . . . . . . . . . . . . . . . . . . 35
C.2. Detection of non-supporting Intermediaries . . . . . . . 36 C.2. Detection of non-supporting Intermediaries . . . . . . . 35
C.3. Implicit Application Indication . . . . . . . . . . . . . 36 C.3. Implicit Application Indication . . . . . . . . . . . . . 36
C.4. Stateless Operation . . . . . . . . . . . . . . . . . . . 37 C.4. Stateless Operation . . . . . . . . . . . . . . . . . . . 36
C.5. No New Vulnerabilities . . . . . . . . . . . . . . . . . 37 C.5. No New Vulnerabilities . . . . . . . . . . . . . . . . . 36
C.6. Detailed Requirements . . . . . . . . . . . . . . . . . . 37 C.6. Detailed Requirements . . . . . . . . . . . . . . . . . . 36
C.6.1. General . . . . . . . . . . . . . . . . . . . . . . . 37 C.6.1. General . . . . . . . . . . . . . . . . . . . . . . . 36
C.6.2. Performance . . . . . . . . . . . . . . . . . . . . . 39 C.6.2. Performance . . . . . . . . . . . . . . . . . . . . . 38
C.6.3. Heterogeneous Support for Solution . . . . . . . . . 41 C.6.3. Heterogeneous Support for Solution . . . . . . . . . 40
C.6.4. Granular Control . . . . . . . . . . . . . . . . . . 43 C.6.4. Granular Control . . . . . . . . . . . . . . . . . . 42
C.6.5. Priority and Policy . . . . . . . . . . . . . . . . . 43 C.6.5. Priority and Policy . . . . . . . . . . . . . . . . . 43
C.6.6. Security . . . . . . . . . . . . . . . . . . . . . . 44 C.6.6. Security . . . . . . . . . . . . . . . . . . . . . . 43
C.6.7. Flexibility and Extensibility . . . . . . . . . . . . 45 C.6.7. Flexibility and Extensibility . . . . . . . . . . . . 44
Appendix D. Considerations for Applications Integrating the DOIC Appendix D. Considerations for Applications Integrating the DOIC
Solution . . . . . . . . . . . . . . . . . . . . . . 46 Solution . . . . . . . . . . . . . . . . . . . . . . 46
D.1. Application Classification . . . . . . . . . . . . . . . 47 D.1. Application Classification . . . . . . . . . . . . . . . 46
D.2. Application Type Overload Implications . . . . . . . . . 48 D.2. Application Type Overload Implications . . . . . . . . . 47
D.3. Request Transaction Classification . . . . . . . . . . . 49 D.3. Request Transaction Classification . . . . . . . . . . . 48
D.4. Request Type Overload Implications . . . . . . . . . . . 50 D.4. Request Type Overload Implications . . . . . . . . . . . 49
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 50
1. Introduction 1. Introduction
This specification defines a base solution for Diameter overload This specification defines a base solution for Diameter overload
control, referred to as Diameter Overload Indication Conveyance control, referred to as Diameter Overload Indication Conveyance
(DOIC), based on the requirements identified in [RFC7068]. (DOIC), based on the requirements identified in [RFC7068].
This specification addresses Diameter overload control between This specification addresses Diameter overload control between
Diameter nodes that support the DOIC solution. The solution, which Diameter nodes that support the DOIC solution. The solution, which
is designed to apply to existing and future Diameter applications, is designed to apply to existing and future Diameter applications,
requires no changes to the Diameter base protocol [RFC6733] and is requires no changes to the Diameter base protocol [RFC6733] and is
deployable in environments where some Diameter nodes do not implement deployable in environments where some Diameter nodes do not implement
the Diameter overload control solution defined in this specification. the Diameter overload control solution defined in this specification.
A new application specification can incorporate the overload control
mechanism specified in this document by making it mandatory to
implement for the application and referencing this specification
normatively. It is the responsibility of the Diameter application
designers to define how overload control mechanisms works on that
application.
Note that the overload control solution defined in this specification Note that the overload control solution defined in this specification
does not address all the requirements listed in [RFC7068]. A number does not address all the requirements listed in [RFC7068]. A number
of overload control related features are left for future of overload control related features are left for future
specifications. See Appendix A for a list of extensions that are specifications. See Appendix A for a list of extensions that are
currently being considered. See Appendix C for an analysis of currently being considered. See Appendix C for an analysis of
conformance to the requirements specified in [RFC7068]. conformance to the requirements specified in [RFC7068].
2. Terminology and Abbreviations 2. Terminology and Abbreviations
Abatement Abatement
Reaction to receipt of an overload report resulting in a reduction Reaction to receipt of an overload report resulting in a reduction
in traffic sent to the reporting node. Abatement actions include in traffic sent to the reporting node. Abatement actions include
diversion and throttling. diversion and throttling.
Abatement Algorithm Abatement Algorithm
A mechanism requested by reporting nodes and used by reacting An extensible mechanism requested by reporting nodes and used by
nodes to reduce the amount of traffic sent during an occurrence of reacting nodes to reduce the amount of traffic sent during an
overload control. occurrence of overload control.
Diversion Diversion
A mechanism used for overload abatement by selecting a different An overload abatement mechanism, where the reacting node selects
path for requests. alternate destinations or paths for for requests.
Host-Routed Requests Host-Routed Requests
Requests that a reacting node knows will be served by a particular Requests that a reacting node knows will be served by a particular
host, either due to the presence of a Destination-Host AVP, or by host, either due to the presence of a Destination-Host AVP, or by
some other local knowledge on the part of the reacting node. some other local knowledge on the part of the reacting node.
Overload Control State (OCS) Overload Control State (OCS)
Reporting and reacting node internally maintained state describing Internal state maintained by a reporting or reacting node
occurrences of overload control. describing occurrences of overload control.
Overload Report (OLR) Overload Report (OLR)
Overload control information for a particular overload occurrence Overload control information for a particular overload occurrence
sent by a reporting node. sent by a reporting node.
Reacting Node Reacting Node
A Diameter node that acts upon an overload report. A Diameter node that acts upon an overload report.
Realm-Routed Requests Realm-Routed Requests
Requests that a reacting node does not know the host that will Requests that a reacting node does not know which host will
service the request. service the request.
Reporting Node Reporting Node
A Diameter node that generates an overload report. (This may or A Diameter node that generates an overload report. (This may or
may not be the overloaded node.) may not be the overloaded node.)
Throttling Throttling
A mechanism for overload abatement that limits the number of A mechanism for overload abatement that limits the number of
requests sent by the DIOC reacting node. Throttling can include a requests sent by the DIOC reacting node. Throttling can include a
Diameter Client not sending requests, or a Diameter Agent or Diameter Client choosing to not send requests, or a Diameter Agent
Server rejecting requests with appropriate error responses. In or Server rejecting requests with appropriate error responses. In
both cases the result of the throttling is a permanent rejection both cases the result of the throttling is a permanent rejection
of the transaction. of the transaction.
3. Solution Overview 3. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
4. Solution Overview
The Diameter Overload Information Conveyance (DOIC) solution allows The Diameter Overload Information Conveyance (DOIC) solution allows
Diameter nodes to request other Diameter nodes to perform overload Diameter nodes to request other Diameter nodes to perform overload
abatement actions, that is, actions to reduce the load offered to the abatement actions, that is, actions to reduce the load offered to the
overloaded node or realm. overloaded node or realm.
A Diameter node that supports DOIC is known as a "DOIC node". Any A Diameter node that supports DOIC is known as a "DOIC node". Any
Diameter node can act as a DOIC node, including Diameter Clients, Diameter node can act as a DOIC node, including Diameter Clients,
Diameter Servers, and Diameter Agents. DOIC nodes are further Diameter Servers, and Diameter Agents. DOIC nodes are further
divided into "Reporting Nodes" and "Reacting Nodes." A reporting divided into "Reporting Nodes" and "Reacting Nodes." A reporting
skipping to change at page 6, line 10 skipping to change at page 6, line 16
Likewise, a Diameter Agent may act as a reacting node from the Likewise, a Diameter Agent may act as a reacting node from the
perspective of upstream nodes, and a reporting node from the perspective of upstream nodes, and a reporting node from the
perspective of downstream nodes. perspective of downstream nodes.
DOIC nodes do not generate new messages to carry DOIC related DOIC nodes do not generate new messages to carry DOIC related
information. Rather, they "piggyback" DOIC information over existing information. Rather, they "piggyback" DOIC information over existing
Diameter messages by inserting new AVPs into existing Diameter Diameter messages by inserting new AVPs into existing Diameter
requests and responses. Nodes indicate support for DOIC, and any requests and responses. Nodes indicate support for DOIC, and any
needed DOIC parameters, by inserting an OC-Supported-Features AVP needed DOIC parameters, by inserting an OC-Supported-Features AVP
(Section 6.2) into existing requests and responses. Reporting nodes (Section 7.2) into existing requests and responses. Reporting nodes
send OLRs by inserting OC-OLR AVPs (Section 6.3). send OLRs by inserting OC-OLR AVPs (Section 7.3).
A given OLR applies to the Diameter realm and application of the A given OLR applies to the Diameter realm and application of the
Diameter message that carries it. If a reporting node supports more Diameter message that carries it. If a reporting node supports more
than one realm and/or application, it reports independently for each than one realm and/or application, it reports independently for each
combination of realm and application. Similarly, the OC-Supported- combination of realm and application. Similarly, the OC-Supported-
Features AVP applies to the realm and application of the enclosing Features AVP applies to the realm and application of the enclosing
message. This implies that a node may support DOIC for one message. This implies that a node may support DOIC for one
application and/or realm, but not another, and may indicate different application and/or realm, but not another, and may indicate different
DOIC parameters for each application and realm for which it supports DOIC parameters for each application and realm for which it supports
DOIC. DOIC.
Reacting nodes perform overload abatement according to an agreed-upon Reacting nodes perform overload abatement according to an agreed-upon
abatement algorithm. An abatement algorithm defines the meaning of abatement algorithm. An abatement algorithm defines the meaning of
some of the parameters of an OLR and the procedures required for some of the parameters of an OLR and the procedures required for
overload abatement. An overload abatement algorithm separates overload abatement. An overload abatement algorithm separates
Diameter requests into two sets. The first set contains the requests Diameter requests into two sets. The first set contains the requests
that are to undergo overload abatement treatment of either throttling that are to undergo overload abatement treatment of either throttling
or diversion. The second set contains the requests that are to be or diversion. The second set contains the requests that are to be
given normal routing treatment. This document specifies a single given normal routing treatment. This document specifies a single
must-support algorithm, namely the "loss" algorithm (Section 5). must-support algorithm, namely the "loss" algorithm (Section 6).
Future specifications may introduce new algorithms. Future specifications may introduce new algorithms.
Overload conditions may vary in scope. For example, a single Overload conditions may vary in scope. For example, a single
Diameter node may be overloaded, in which case reacting nodes may Diameter node may be overloaded, in which case reacting nodes may
attempt to send requests to other destinations. On the other hand, attempt to send requests to other destinations. On the other hand,
an entire Diameter realm may be overloaded, in which case such an entire Diameter realm may be overloaded, in which case such
attempts would do harm. DOIC OLRs have a concept of "report type" attempts would do harm. DOIC OLRs have a concept of "report type"
(Section 6.6), where the type defines such behaviors. Report types (Section 7.6), where the type defines such behaviors. Report types
are extensible. This document defines report types for overload of a are extensible. This document defines report types for overload of a
specific host, and for overload of an entire realm. specific host, and for overload of an entire realm.
A report of type "HOST_REPORT" is sent to indicate the overload of a DOIC works through non supporting Diameter Agents that properly pass
specific host, identified by the Origin-Host AVP of the message unknown AVPs unchanged.
containing the OLR, for the application-id indicated in the
transaction. When receiving an OLR of type "HOST_REPORT", a reacting
node applies overload abatement treatment to the host-routed requests
identified by the overload abatement algorithm (see definition in
Section 2) sent for this application to the overloaded host.
A report of type "REALM_REPORT" is sent to indicate the overload of a
realm for the application-id indicated in the transaction. The
overloaded realm is identified by the Destination-Realm AVP of the
message containing the OLR. When receiving an OLR of type
"REALM_REPORT", a reacting node applies overload abatement treatment
to realm-routed requests identified by the overload abatement
algorithm (see definition in Section 2) sent for this application to
the overloaded realm.
While a reporting node sends OLRs to "adjacent" reacting nodes, nodes
that are "adjacent" for DOIC purposes may not be adjacent from a
Diameter, or transport, perspective. For example, one or more
Diameter agents that do not support DOIC may exist between a given
pair of reporting and reacting nodes, as long as those agents pass
unknown AVPs through unchanged. The report types described in this
document can safely pass through non-supporting agents. This may not
be true for report types defined in future specifications.
3.1. Piggybacking 4.1. Piggybacking
There is no new Diameter application defined to carry overload There is no new Diameter application defined to carry overload
related AVPs. The overload control AVPs defined in this related AVPs. The overload control AVPs defined in this
specification have been designed to be piggybacked on top of existing specification have been designed to be piggybacked on top of existing
application messages. This is made possible by adding overload application messages. This is made possible by adding the optional
control AVPs, the OC-OLR AVP and the OC-Supported-Features AVP, as overload control AVPs OC-OLR and OC-Supported-Features into existing
optional AVPs into existing commands when the corresponding Command commands.
Code Format (CCF) specification allows adding new optional AVPs (see
Section 1.3.4 of [RFC6733]).
Reacting nodes indicate support for DOIC by including the OC- Reacting nodes indicate support for DOIC by including the OC-
Supported-Features AVP in all request messages originated or relayed Supported-Features AVP in all request messages originated or relayed
by the reacting node. by the reacting node.
Reporting nodes indicate support for DOIC by including the OC- Reporting nodes indicate support for DOIC by including the OC-
Supported-Features AVP in all answer messages originated or relayed Supported-Features AVP in all answer messages originated or relayed
by the reporting node that are in response to a request that by the reporting node that are in response to a request that
contained the OC-Supported-Features AVP. Reporting nodes also contained the OC-Supported-Features AVP. Reporting nodes may include
include overload reports using the OC-OLR AVP in answer messages. overload reports using the OC-OLR AVP in answer messages.
Note that the overload control solution does not have fixed server Note that the overload control solution does not have fixed server
and client roles. The DOIC node role is determined based on the and client roles. The DOIC node role is determined based on the
message type: whether the message is a request (i.e. sent by a message type: whether the message is a request (i.e. sent by a
"reacting node") or an answer (i.e. send by a "reporting node"). "reacting node") or an answer (i.e. sent by a "reporting node").
Therefore, in a typical "client-server" deployment, the Diameter Therefore, in a typical "client-server" deployment, the Diameter
Client MAY report its overload condition to the Diameter Server for Client may report its overload condition to the Diameter Server for
any Diameter Server initiated message exchange. An example of such any Diameter Server initiated message exchange. An example of such
is the Diameter Server requesting a re-authentication from a Diameter is the Diameter Server requesting a re-authentication from a Diameter
Client. Client.
3.2. DOIC Capability Announcement 4.2. DOIC Capability Announcement
The DOIC solution supports the ability for Diameter nodes to The DOIC solution supports the ability for Diameter nodes to
determine if other nodes in the path of a request support the determine if other nodes in the path of a request support the
solution. This capability is referred to as DOIC Capability solution. This capability is referred to as DOIC Capability
Announcement (DCA) and is separate from Diameter Capability Exchange. Announcement (DCA) and is separate from Diameter Capability Exchange.
The DCA mechanism uses the OC-Supported-Features AVPs to indicate the The DCA mechanism uses the OC-Supported-Features AVPs to indicate the
Diameter overload features supported. Diameter overload features supported.
The first node in the path of a Diameter request that supports the The first node in the path of a Diameter request that supports the
DOIC solution inserts the OC-Supported-Features AVP in the request DOIC solution inserts the OC-Supported-Features AVP in the request
message. message.
The individual features supported by the DOIC nodes are indicated in
the OC-Feature-Vector AVP. Any semantics associated with the
features will be defined in extension specifications that introduce
the features.
Note: As discussed elsewhere in the document, agents in the path Note: As discussed elsewhere in the document, agents in the path
of the request can modify the OC-Supported-Features AVP. of the request can modify the OC-Supported-Features AVP.
Note: The DOIC solution must support deployments where Diameter Note: The DOIC solution must support deployments where Diameter
Clients and/or Diameter Servers do not support the DOIC solution. Clients and/or Diameter Servers do not support the DOIC solution.
In this scenario, Diameter Agents that support the DOIC solution In this scenario, Diameter Agents that support the DOIC solution
may handle overload abatement for the non supporting Diameter may handle overload abatement for the non supporting Diameter
nodes. In this case the DOIC agent will insert the OC-Supported- nodes. In this case the DOIC agent will insert the OC-Supported-
Features AVP in requests that do not already contain one, telling Features AVP in requests that do not already contain one, telling
the reporting node that there is a DOIC node that will handle the reporting node that there is a DOIC node that will handle
overload abatement. For transactions where there was an OC- overload abatement. For transactions where there was an OC-
Supporting-Features AVP in the request, the agent will insert the Supporting-Features AVP in the request, the agent will insert the
OC-Supported-Features AVP in answers, telling the reacting node OC-Supported-Features AVP in answers, telling the reacting node
that there is a reporting node. that there is a reporting node.
The OC-Feature-Vector AVP will contain an indication of support for The OC-Feature-Vector AVP will always contain an indication of
the loss overload abatement algorithm defined in this specification support for the loss overload abatement algorithm defined in this
(see Section 5). This ensures that there is at least one commonly specification (see Section 6). This ensures that a reporting node
supported overload abatement algorithm between the reporting node and always supports at least one of the advertized abatement algorithms
the reacting node(s) in the path of the request. received in a request messages.
The reporting node inserts the OC-Supported-Features AVP in all The reporting node inserts the OC-Supported-Features AVP in all
answer messages to requests that contained the OC-Supported-Features answer messages to requests that contained the OC-Supported-Features
AVP. The contents of the reporting node's OC-Supported-Features AVP AVP. The contents of the reporting node's OC-Supported-Features AVP
indicate the set of Diameter overload features supported by the indicate the set of Diameter overload features supported by the
reporting node. This specification defines one exception - the reporting node. This specification defines one exception - the
reporting node only includes an indication of support for one reporting node only includes an indication of support for one
overload abatement algorithm, independent of the number of overload overload abatement algorithm, independent of the number of overload
abatement algorithms actually supported by the reacting node. The abatement algorithms actually supported by the reacting node. The
overload abatement algorithm indicated is the algorithm that the overload abatement algorithm indicated is the algorithm that the
skipping to change at page 9, line 15 skipping to change at page 8, line 49
requested. requested.
Note that the loss algorithm defined in this document is a Note that the loss algorithm defined in this document is a
stateless abatement algorithm. As a result it does not require stateless abatement algorithm. As a result it does not require
any actions by reacting nodes prior to the receipt of an overload any actions by reacting nodes prior to the receipt of an overload
report. Stateful abatement algorithms that base the abatement report. Stateful abatement algorithms that base the abatement
logic on a history of request messages sent might require reacting logic on a history of request messages sent might require reacting
nodes to maintain state in advance of receiving an overload report nodes to maintain state in advance of receiving an overload report
to ensure that the overload reports can be properly handled. to ensure that the overload reports can be properly handled.
Reporting nodes are allowed to change the overload abatement Reporting nodes can change the overload abatement algorithm indicated
algorithm indicated in the OC-Feature-Vector AVP if the reporting in the OC-Feature-Vector AVP if the reporting node is not currently
node is not currently in an overload condition and sending overload in an overload condition and sending overload reports. The reporting
reports. The reporting node is not allowed to change the overload node is not allowed to change the overload abatement algorithm while
abatement algorithm while the reporting node is in an overload the reporting node is in an overload condition.
condition.
The individual features supported by the DOIC nodes are indicated in
the OC-Feature-Vector AVP. Any semantics associated with the
features will be defined in extension specifications that introduce
the features.
The DCA mechanism must also allow the scenario where the set of The DCA mechanism must also allow the scenario where the set of
features supported by the sender of a request and by agents in the features supported by the sender of a request and by agents in the
path of a request differ. In this case, the agent updates the OC- path of a request differ. In this case, the agent can update the OC-
Supported-Features AVP to reflect the mixture of the two sets of Supported-Features AVP to reflect the mixture of the two sets of
supported features. supported features.
Note: The logic to determine the content of the modified OC- Note: The logic to determine if the content of the OC-Supported-
Supported-Features AVP is out-of-scope for this specification and Features AVP should be changed is out-of-scope for this document,
is left to implementation decisions. Care must be taken not to as is the logic to determine the content of a modified OC-
introduce interoperability issues for downstream or upstream DOIC Supported-Features AVP. These are left to implementation
nodes. decisions. Care must be taken not to introduce interoperability
issues for downstream or upstream DOIC nodes.
3.3. DOIC Overload Condition Reporting 4.3. DOIC Overload Condition Reporting
As with DOIC capability announcement, overload condition reporting As with DOIC capability announcement, overload condition reporting
uses new AVPs (Section 6.3) to indicate an overload condition. uses new AVPs (Section 7.3) to indicate an overload condition.
The OC-OLR AVP is referred to as an overload report. The OC-OLR AVP The OC-OLR AVP is referred to as an overload report. The OC-OLR AVP
includes the type of report, a sequence number, the length of time includes the type of report, a sequence number, the length of time
that the report is valid and abatement algorithm specific AVPs. that the report is valid and abatement algorithm specific AVPs.
Two types of overload reports are defined in this document, host Two types of overload reports are defined in this document: host
reports and realm reports. reports and realm reports.
A report of type "HOST_REPORT" is sent to indicate the overload of a A report of type "HOST_REPORT" is sent to indicate the overload of a
specific Diameter node for the application-id indicated in the specific host, identified by the Origin-Host AVP of the message
transaction. When receiving an OLR of type host, a reacting node containing the OLR, for the application-id indicated in the
applies overload abatement to what is referred to in this document as transaction. When receiving an OLR of type "HOST_REPORT", a reacting
host-routed requests. The reacting node applies overload abatement node applies overload abatement treatment to the host-routed requests
on those host-routed requests which the reacting node knows will be identified by the overload abatement algorithm (see definition in
served by the server that matches the Origin-Host AVP of the received Section 2) sent for this application to the overloaded host.
message that contained the received OLR of type host.
A report of type "REALM_REPORT" applies to realm-routed requests for A report of type "REALM_REPORT" is sent to indicate the overload of a
a specific realm as indicated in the Destination-Realm AVP. realm for the application-id indicated in the transaction. The
overloaded realm is identified by the Destination-Realm AVP of the
message containing the OLR. When receiving an OLR of type
"REALM_REPORT", a reacting node applies overload abatement treatment
to realm-routed requests identified by the overload abatement
algorithm (see definition in Section 2) sent for this application to
the overloaded realm.
This document assumes that there is a single source for realm-reports This document assumes that there is a single source for realm-reports
for a given realm, or that if multiple nodes can send realm reports, for a given realm, or that if multiple nodes can send realm reports,
that each such node has full knowledge of the overload state of the that each such node has full knowledge of the overload state of the
entire realm. A reacting node cannot distinguish between receiving entire realm. A reacting node cannot distinguish between receiving
realm-reports from a single node, or from multiple nodes. realm-reports from a single node, or from multiple nodes.
Note: Known issues exist if multiple sources for overload reports Note: Known issues exist if multiple sources for overload reports
which apply to the same Diameter entity exist. Reacting nodes which apply to the same Diameter entity exist. Reacting nodes
have no way of determining the source and, as such, will treat have no way of determining the source and, as such, will treat
them as coming from a single source. Variance in sequence numbers them as coming from a single source. Variance in sequence numbers
between the two sources can then cause incorrect overload between the two sources can then cause incorrect overload
abatement treatment to be applied for indeterminate periods of abatement treatment to be applied for indeterminate periods of
time. time.
Reporting nodes are responsible for determining the need for a Reporting nodes are responsible for determining the need for a
reduction of traffic. The method for making this determination is reduction of traffic. The method for making this determination is
implementation specific and depend on the type of overload report implementation specific and depend on the type of overload report
being generated. A host-report, for instance, will generally be being generated. A host-report might be generated by tracking use of
generated by tracking utilization of resources required by the host resources required by the host to handle transactions for the
to handle transactions for the Diameter application. A realm-report Diameter application. A realm-report generally impacts the traffic
generally impacts the traffic sent to multiple hosts and, as such, sent to multiple hosts and, as such, requires tracking the capacity
requires tracking the capacity all servers for realm-routed requests of all servers able to handle realm- routed requests for the
for the application and realm. application and realm.
Once a reporting node determines the need for a reduction in traffic, Once a reporting node determines the need for a reduction in traffic,
it uses the DOIC defined AVPs to report on the condition. These AVPs it uses the DOIC defined AVPs to report on the condition. These AVPs
are included in answer messages sent or relayed by the reporting are included in answer messages sent or relayed by the reporting
node. The reporting node indicates the overload abatement algorithm node. The reporting node indicates the overload abatement algorithm
that is to be used to handle the traffic reduction in the OC- that is to be used to handle the traffic reduction in the OC-
Supported-Features AVP. The OC-OLR AVP is used to communicate Supported-Features AVP. The OC-OLR AVP is used to communicate
information about the requested reduction. information about the requested reduction.
Reacting nodes, upon receipt of an overload report, are responsible Reacting nodes, upon receipt of an overload report, applying the
for applying the overload abatement algorithm to traffic impacted by overload abatement algorithm to traffic impacted by the overload
the overload report. The method used to determine the requests that report. The method used to determine the requests that are to
are to receive overload abatement treatment is dependent on the receive overload abatement treatment is dependent on the abatement
abatement algorithm. The loss abatement algorithm is defined in this algorithm. The loss abatement algorithm is defined in this document
document (Section 5). Other abatement algorithms can be defined in (Section 6). Other abatement algorithms can be defined in extensions
extensions to the DOIC solutions. to the DOIC solutions.
Two types of overload abatement treatment are defined, diversion and Two types of overload abatement treatment are defined, diversion and
throttling. Reacting nodes are responsible for determining which throttling. Reacting nodes are responsible for determining which
treatment is appropriate for individual requests. treatment is appropriate for individual requests.
As the conditions that lead to the generation of the overload report As the conditions that lead to the generation of the overload report
change the reporting node can send new overload reports requesting change the reporting node can send new overload reports requesting
greater reduction if the condition gets worse or less reduction if greater reduction if the condition gets worse or less reduction if
the condition improves. The reporting node sends an overload report the condition improves. The reporting node sends an overload report
with a duration of zero to indicate that the overload condition has with a duration of zero to indicate that the overload condition has
ended and need for use of the abatement algorithm to reduce traffic ended and abatement is no longer needed.
sent is no longer needed.
The reacting node also determines when the overload report expires The reacting node also determines when the overload report expires
based on the OC-Validity-Duration AVP in the overload report and based on the OC-Validity-Duration AVP in the overload report and
stops applying the abatement algorithm when the report expires. stops applying the abatement algorithm when the report expires.
3.4. DOIC Extensibility 4.4. DOIC Extensibility
The DOIC solution is designed to be extensible. This extensibility The DOIC solution is designed to be extensible. This extensibility
is based on existing Diameter based extensibility mechanisms, along is based on existing Diameter based extensibility mechanisms, along
with the DOIC capability announcement mechanism. with the DOIC capability announcement mechanism.
There are multiple categories of extensions that are expected. This There are multiple categories of extensions that are expected. This
includes the definition of new overload abatement algorithms, the includes the definition of new overload abatement algorithms, the
definition of new report types and the definition of new scopes of definition of new report types and the definition of new scopes of
messages impacted by an overload report. messages impacted by an overload report.
The DOIC solution uses the OC-Supported-Features AVP for DOIC nodes A DOIC node communicates supported features by including them in the
to communicate supported features. The specific features supported OC-Feature-Vector AVP, as a sub-AVP of OC-Supported-Features. Any
by the DOIC node are indicated in the OC-Feature-Vector AVP. DOIC non-backwards compatible DOIC extensions define new values for the
extensions that require new normative behavior define new values for OC-Feature-Vector AVP. DOIC extensions also have the ability to add
the OC-Feature-Vector AVP. DOIC extensions also have the ability to new AVPs to the OC-Supported-Features AVP, if additional information
add new AVPs to the OC-Supported-Features AVP, if additional about the new feature is required.
information about the new feature is required.
Reporting nodes use the OC-OLR AVP to communicate overload Overload reports can be also extended by adding new sub-AVPs to the
occurrences. This AVP can also be extended to add new AVPs allowing OC-OLR AVP, allowing reporting nodes to communicate additional
reporting nodes to communicate additional information about handling information about handling an overload condition.
an overload condition.
If necessary, new extensions can also define new AVPs that are not If necessary, new extensions can also define new AVPs that are not
part of the OC-Supported-Features and OC-OLR group AVPs. It is, part of the OC-Supported-Features and OC-OLR group AVPs. It is,
however, recommended that DOIC extensions use the OC-Supported- however, recommended that DOIC extensions use the OC-Supported-
Features AVP and OC-OLR AVP to carry all DOIC related AVPs. Features AVP and OC-OLR AVP to carry all DOIC related AVPs.
3.5. Simplified Example Architecture 4.5. Simplified Example Architecture
Figure 1 illustrates the simplified architecture for Diameter Figure 1 illustrates the simplified architecture for Diameter
overload information conveyance. overload information conveyance.
Realm X Same or other Realms Realm X Same or other Realms
<--------------------------------------> <----------------------> <--------------------------------------> <---------------------->
+--^-----+ : (optional) : +--^-----+ : (optional) :
|Diameter| : : |Diameter| : :
|Server A|--+ .--. : +---^----+ : .--. |Server A|--+ .--. : +---^----+ : .--.
skipping to change at page 12, line 39 skipping to change at page 12, line 34
Diameter Application Y Diameter Application Y Diameter Application Y Diameter Application Y
Figure 1: Simplified architecture choices for overload indication Figure 1: Simplified architecture choices for overload indication
delivery delivery
In Figure 1, the Diameter overload indication can be conveyed (1) In Figure 1, the Diameter overload indication can be conveyed (1)
end-to-end between servers and clients or (2) between servers and end-to-end between servers and clients or (2) between servers and
Diameter agent inside the realm and then between the Diameter agent Diameter agent inside the realm and then between the Diameter agent
and the clients. and the clients.
4. Solution Procedures 5. Solution Procedures
This section outlines the normative behavior for the DOIC solution. This section outlines the normative behavior for the DOIC solution.
4.1. Capability Announcement 5.1. Capability Announcement
This section defines DOIC Capability Announcement (DCA) behavior. This section defines DOIC Capability Announcement (DCA) behavior.
4.1.1. Reacting Node Behavior Note: This specification assumes that changes in DOIC node
capabilities are relatively rare events that occur as a result of
administrative action. Reacting nodes ought to minimize changes
that force the reporting node to change the features being used,
especially during active overload conditions. But even if
reacting nodes avoid such changes, reporting nodes still have to
be prepared for them to occur. For example, differing
capabilities between multiple reacting nodes may still force a
reporting node to select different features on a per-transaction
basis.
5.1.1. Reacting Node Behavior
A reacting node MUST include the OC-Supported-Features AVP in all A reacting node MUST include the OC-Supported-Features AVP in all
requests. It MAY include the OC-Feature-Vector AVP. If it does so, requests. It MAY include the OC-Feature-Vector AVP, as a sub-avp of
it MUST indicate support for the "loss" algorithm. If the reacting OC-Supported-Features. If it does so, it MUST indicate support for
node is configured to support features (including other algorithms) the "loss" algorithm. If the reacting node is configured to support
in addition to the loss algorithm, it MUST indicate such support in features (including other algorithms) in addition to the loss
an OC-Feature-Vector AVP. algorithm, it MUST indicate such support in an OC-Feature-Vector AVP.
An OC-Supported-Features AVP in answer messages indicates there is a An OC-Supported-Features AVP in answer messages indicates there is a
reporting node for the transaction. The reacting node MAY take reporting node for the transaction. The reacting node MAY take
action, for example creating state for some stateful abatement action, for example creating state for some stateful abatement
algorithm, based on the features indicated in the OC-Feature-Vector algorithm, based on the features indicated in the OC-Feature-Vector
AVP. AVP.
Note: The loss abatement algorithm does not require stateful Note: The loss abatement algorithm does not require stateful
behavior when there is no active overload report. This behavior behavior when there is no active overload report.
is described in Section 4.2 and Section 5.
4.1.2. Reporting Node Behavior 5.1.2. Reporting Node Behavior
Upon receipt of a request message, a reporting node determines if Upon receipt of a request message, a reporting node determines if
there is a reacting node for the transaction based on the presence of there is a reacting node for the transaction based on the presence of
the OC-Supported-Features AVP in the request message. the OC-Supported-Features AVP in the request message.
If the request message contains an OC-Supported-Features AVP then a If the request message contains an OC-Supported-Features AVP then a
reporting node MUST include the OC-Supported-Features AVP in the reporting node MUST include the OC-Supported-Features AVP in the
answer message for that transaction. answer message for that transaction.
Note: Capability announcement is done on a per transaction basis.
The reporting node cannot assume that the capabilities announced
by a reacting node will be the same between transactions.
A reporting node MUST NOT include the OC-Supported-Features AVP, OC- A reporting node MUST NOT include the OC-Supported-Features AVP, OC-
OLR AVP or any other overload control AVPs defined in extension OLR AVP or any other overload control AVPs defined in extension
drafts in response messages for transactions where the request drafts in response messages for transactions where the request
message does not include the OC-Supported-Features AVP. Lack of the message does not include the OC-Supported-Features AVP. Lack of the
OC-Supported-Features AVP in the request message indicates that there OC-Supported-Features AVP in the request message indicates that there
is no reacting node for the transaction. is no reacting node for the transaction.
A reporting node knows what overload control functionality is A reporting node knows what overload control functionality is
supported by the reacting node based on the content of the OC- supported by the reacting node based on the content or absence of the
Feature-Vector AVP in the request message. OC-Feature-Vector AVP within the OC-Supported-Features AVP in the
request message.
A reporting node MUST indicate support for one and only one abatement A reporting node MUST indicate support for one and only one abatement
algorithm in the OC-Feature-Vector AVP. The abatement algorithm algorithm in the OC-Feature-Vector AVP. The abatement algorithm
selected MUST indicate the abatement algorithm the reporting node selected MUST indicate the abatement algorithm the reporting node
wants the reacting node to use when the reporting node enters an wants the reacting node to use when the reporting node enters an
overload condition. overload condition.
The abatement algorithm selected MUST be from the set of abatement The abatement algorithm selected MUST be from the set of abatement
algorithms contained in the request message's OC-Feature-Vector AVP. algorithms contained in the request message's OC-Feature-Vector AVP.
A reporting node that selects the loss algorithm may do so by A reporting node that selects the loss algorithm may do so by
including the OC-Feature-Vector AVP with an explicit indication of including the OC-Feature-Vector AVP with an explicit indication of
the loss algorithm, or it MAY omit OC-Feature-Vector. If it selects the loss algorithm, or it MAY omit OC-Feature-Vector. If it selects
a different algorithm, it MUST include the OC-Feature-Vector AVP with a different algorithm, it MUST include the OC-Feature-Vector AVP with
an explicit indication of the selected algorithm. an explicit indication of the selected algorithm.
For an ongoing overload condition, a reporting node MUST NOT change A reporting node MUST NOT change the selected algorithm during the
the selected algorithm during the period of time that it is in an period of time that starts when entering an overload condition and
overload condition and, as a result, is sending OC-OLR AVPs in answer ends when the associated OCS becomes invalid in all reacting nodes.
messages.
The reporting node MAY change the overload abatement algorithm The reporting node MAY change the overload abatement algorithm
indicated in the OC-Supported-Features AVP at any time as long as no indicated in the OC-Supported-Features AVP at any time as long as no
previously sent OLRs may be active. previously sent OLRs may be active.
The reporting node SHOULD indicate support for other DOIC features The reporting node SHOULD indicate support for other DOIC features
defined in extension drafts that it supports and that apply to the defined in extension drafts that it supports and that apply to the
transaction. transaction. It does so using the OC-Feature-Vector AVP.
Note: Not all DOIC features will apply to all Diameter Note: Not all DOIC features will apply to all Diameter
applications or deployment scenarios. The features included in applications or deployment scenarios. The features included in
the OC-Feature-Vector AVP are based on local reporting node the OC-Feature-Vector AVP are based on local reporting node
policy. policy.
4.1.3. Agent Behavior 5.1.3. Agent Behavior
Diameter Agents that support DOIC SHOULD ensure that all messages Diameter Agents that support DOIC MAY ensure that all messages
relayed by the agent contain the OC-Supported-Features AVP. relayed by the agent contain the OC-Supported-Features AVP.
A Diameter Agent SHOULD take on reacting node behavior for Diameter A Diameter Agent SHOULD take on reacting node behavior for Diameter
endpoints that do not support the DOIC solution. A Diameter Agent endpoints that do not support the DOIC solution. A Diameter Agent
detects that a Diameter endpoint does not support DOIC reacting node detects that a Diameter endpoint does not support DOIC reacting node
behavior when there is no OC-Supported-Features AVP in a request behavior when there is no OC-Supported-Features AVP in a request
message. message.
For a Diameter Agent to be a reacting node for a non supporting For a Diameter Agent to be a reacting node for a non supporting
Diameter endpoint, the Diameter Agent MUST include the OC-Supported- Diameter endpoint, the Diameter Agent MUST include the OC-Supported-
Features AVP in request messages it receives that do not contain the Features AVP in request messages it relays that do not contain the
OC-Supported-Features AVP. OC-Supported-Features AVP.
A Diameter Agent SHOULD take on reporting node behavior for Diameter A Diameter Agent MAY take on reporting node behavior for Diameter
endpoints that do not support the DOIC solution. A Diameter Agent endpoints that do not support the DOIC solution. The Diameter Agent
detects that a Diameter endpoint does not support DOIC reporting node MUST have visibility to all traffic destined for the non supporting
behavior when there is no OC-Supported-Features AVP in an answer host in order to become the reporting node for the Diameter endpoint.
message for a transaction that contained the OC-Supported-Features A Diameter Agent detects that a Diameter endpoint does not support
AVP in the request message. DOIC reporting node behavior when there is no OC-Supported-Features
AVP in an answer message for a transaction that contained the OC-
For a Diameter Agent to take on reporting node behavior for a non Supported-Features AVP in the request message.
supporting Diameter endpoint the Diameter Agent MUST include the OC-
Supported-Features AVP in answer messages it receives that do not
contain the OC-Supported-Features AVP.
As with a Diameter endpoint taking on reporting node behavior, a
Diameter Agent MUST only include the OC-Supported-Features AVP in
answer messages for transactions where the request message received
by the Diameter Agent had an OC-Supported-Features AVP.
If a request message already has the OC-Supported-Features AVP then a If a request already has the OC-Supported-Features AVP, a Diameter
Diameter Agent MAY leave it unchanged in the relayed message or MAY agent MAY modify it to reflect the features appropriate for the
modify it to reflect the features appropriate for the transaction. transaction. Otherwise, the agent relays the OC-Supported-Features
AVP without change.
For instance, if the agent supports a superset of the features For instance, if the agent supports a superset of the features
reported by the reacting node then the agent might choose, based reported by the reacting node then the agent might choose, based
on local policy, to advertise that superset of features to the on local policy, to advertise that superset of features to the
reporting node. reporting node.
If the Diameter Agent changes the OC-Supported-Features AVP in a If the Diameter Agent changes the OC-Supported-Features AVP in a
request message then it is likely it will also need to modify the OC- request message then it is likely it will also need to modify the OC-
Supported-Features AVP in the answer message for the transaction. As Supported-Features AVP in the answer message for the transaction. A
such, a Diameter Agent MAY modify the OC-Supported-Features AVP Diameter Agent MAY modify the OC-Supported-Features AVP carried in
carried in answer messages. answer messages.
When making changes to the OC-Supported-Features AVP the Diameter When making changes to the OC-Supported-Features or OC-OLR AVPs, the
Agent needs to ensure that there is no ambiguity in DOIC behavior for Diameter Agent needs to ensure consistency in its behavior with both
both upstream and downstream DOIC nodes. upstream and downstream DOIC nodes.
4.2. Overload Report Processing 5.2. Overload Report Processing
4.2.1. Overload Control State 5.2.1. Overload Control State
Both reacting and reporting nodes maintain Overload Control State Both reacting and reporting nodes maintain Overload Control State
(OCS) for active overload conditions. The following sections define (OCS) for active overload conditions. The following sections define
behavior associated with that OCS. behavior associated with that OCS.
4.2.1.1. Overload Control State for Reacting Nodes 5.2.1.1. Overload Control State for Reacting Nodes
A reacting node SHOULD maintain the following OCS per supported A reacting node SHOULD maintain the following OCS per supported
Diameter application: Diameter application:
o A host-type OCS entry for each Destination-Host to which it sends o A host-type OCS entry for each Destination-Host to which it sends
host-type requests and host-type requests and
o A realm-type OCS entry for each Destination-Realm to which it o A realm-type OCS entry for each Destination-Realm to which it
sends realm-type requests. sends realm-type requests.
A host-type OCS entry is identified by the pair of application-id and A host-type OCS entry is identified by the pair of application-id and
the node's DiameterIdentity. the node's DiameterIdentity.
A realm-type OCS entry is identified by the pair of application-d and A realm-type OCS entry is identified by the pair of application-id
realm. and realm.
The host-type and realm-type OCS entries MAY include the following The host-type and realm-type OCS entries MAY include the following
information (the actual information stored is an implementation information (the actual information stored is an implementation
decision): decision):
o Sequence number (as received in OC-OLR) o Sequence number (as received in OC-OLR)
o Time of expiry (derived from OC-Validity-Duration AVP received in o Time of expiry (derived from OC-Validity-Duration AVP received in
the OC-OLR AVP and time of reception of the message carrying OC- the OC-OLR AVP and time of reception of the message carrying OC-
OLR AVP) OLR AVP)
o Selected Abatement Algorithm (as received in the OC-Supported- o Selected Abatement Algorithm (as received in the OC-Supported-
Features AVP) Features AVP)
o Abatement Algorithm specific input data (as received in the OC-OLR o Abatement Algorithm specific input data (as received in the OC-OLR
AVP, for example, OC-Reduction-Percentage for the Loss abatement AVP, for example, OC-Reduction-Percentage for the Loss abatement
algorithm) algorithm)
4.2.1.2. Overload Control State for Reporting Nodes 5.2.1.2. Overload Control State for Reporting Nodes
A reporting node SHOULD maintain OCS entries per supported Diameter A reporting node SHOULD maintain OCS entries per supported Diameter
application, per supported (and eventually selected) Abatement application, per supported (and eventually selected) Abatement
Algorithm and per report-type. Algorithm and per report-type.
An OCS entry is identified by the tuple of Application-Id, Report- An OCS entry is identified by the tuple of Application-Id, Report-
Type and Abatement Algorithm and MAY include the following Type and Abatement Algorithm and MAY include the following
information (the actual information stored is an implementation information (the actual information stored is an implementation
decision): decision):
o Sequence number o Sequence number
o Validity Duration o Validity Duration
o Expiration Time o Expiration Time
o Algorithm specific input data (for example, the Reduction o Algorithm specific input data (for example, the Reduction
Percentage for the Loss Abatement Algorithm) Percentage for the Loss Abatement Algorithm)
4.2.1.3. Reacting Node Maintenance of Overload Control State 5.2.1.3. Reacting Node Maintenance of Overload Control State
When a reacting node receives an OC-OLR AVP, it MUST determine if it When a reacting node receives an OC-OLR AVP, it MUST determine if it
is for an existing or new overload condition. is for an existing or new overload condition.
Note: For the remainder of this section the term OLR refers to the Note: For the remainder of this section the term OLR refers to the
combination of the contents of the received OC-OLR AVP and the combination of the contents of the received OC-OLR AVP and the
abatement algorithm indicated in the received OC-Supported- abatement algorithm indicated in the received OC-Supported-
Features AVP. Features AVP.
When receiving an answer message with multiple OLRs or different When receiving an answer message with multiple OLRs of different
types, a reporting node MUST process each received OLR. supported report types, a reacting node MUST process each received
OLR.
When receiving an OC-OLR AVPs with unknown values, a reacting node When receiving an answer message with multiple OLRs and multiple of
SHOULD be silently discarded by reacting nodes and the event SHOULD the OLRs are of the same supported report types, a reacting node
be logged. SHOULD ignore the duplicated OLRs.
A reacting node SHOULD ignore an OC-OLR with a OC-Report-Type AVP
that contains an unrecognized value.
The OLR is for an existing overload condition if a reacting node has The OLR is for an existing overload condition if a reacting node has
an OCS that matches the received OLR. an OCS that matches the received OLR.
For a host-report this means it matches the application-id and the For a host-report this means it matches the application-id and the
host's DiameterIdentity in an existing host OCS entry. host's DiameterIdentity in an existing host OCS entry.
For a realm-report this means it matches the application-id and the For a realm-report this means it matches the application-id and the
realm in an existing realm OCS entry. realm in an existing realm OCS entry.
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reacting node MUST update the OCS entry as being expired. reacting node MUST update the OCS entry as being expired.
Note: It is not necessarily appropriate to delete the OCS entry, Note: It is not necessarily appropriate to delete the OCS entry,
as there is recommended behavior that the reacting node slowly as there is recommended behavior that the reacting node slowly
returns to full traffic when ending an overload abatement period. returns to full traffic when ending an overload abatement period.
The reacting node does not delete an OCS when receiving an answer The reacting node does not delete an OCS when receiving an answer
message that does not contain an OC-OLR AVP (i.e. absence of OLR message that does not contain an OC-OLR AVP (i.e. absence of OLR
means "no change"). means "no change").
4.2.1.4. Reporting Node Maintenance of Overload Control State 5.2.1.4. Reporting Node Maintenance of Overload Control State
A reporting node SHOULD create a new OCS entry when entering an A reporting node SHOULD create a new OCS entry when entering an
overload condition. overload condition.
Note: If a reporting node knows through absence of the OC- Note: If a reporting node knows through absence of the OC-
Supported-Features AVP in received messages that there are no Supported-Features AVP in received messages that there are no
reacting nodes supporting DOIC then the reporting node can choose reacting nodes supporting DOIC then the reporting node can choose
to not create OCS entries. to not create OCS entries.
When generating a new OCS entry the sequence number SHOULD be set to When generating a new OCS entry the sequence number SHOULD be set to
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For instance, if a reporting node wishes to instruct reacting For instance, if a reporting node wishes to instruct reacting
nodes to continue overload abatement for a longer period of time nodes to continue overload abatement for a longer period of time
than originally communicated. This also applies if the reporting than originally communicated. This also applies if the reporting
node wishes to shorten the period of time that overload abatement node wishes to shorten the period of time that overload abatement
is to continue. is to continue.
A reporting node MUST NOT update the abatement algorithm in an active A reporting node MUST NOT update the abatement algorithm in an active
OCS entry. OCS entry.
A reporting node MUST update an OCS entry when it wishes to adjust A reporting node MUST update an OCS entry when it wishes to adjust
any abatement algorithm specific parameters, including the reduction any abatement algorithm specific parameters, including, for example,
percentage used for the Loss abatement algorithm. the reduction percentage used for the Loss abatement algorithm.
For instance, if a reporting node wishes to change the reduction For instance, if a reporting node wishes to change the reduction
percentage either higher, if the overload condition has worsened, percentage either higher, if the overload condition has worsened,
or lower, if the overload condition has improved, then the or lower, if the overload condition has improved, then the
reporting node would update the appropriate OCS entry. reporting node would update the appropriate OCS entry.
A reporting node MUST update the sequence number associated with the A reporting node MUST increment the sequence number associated with
OCS entry anytime the contents of the OCS entry are changed. This the OCS entry anytime the contents of the OCS entry are changed.
will result in a new sequence number being sent to reacting nodes, This will result in a new sequence number being sent to reacting
instructing reacting nodes to process the OC-OLR AVP. nodes, instructing reacting nodes to process the OC-OLR AVP.
A reporting node SHOULD update an OCS entry with a validity duration A reporting node SHOULD update an OCS entry with a validity duration
of zero ("0") when the overload condition ends. of zero ("0") when the overload condition ends.
Note: If a reporting node knows that the OCS entries in the Note: If a reporting node knows that the OCS entries in the
reacting nodes are near expiration then the reporting node might reacting nodes are near expiration then the reporting node might
decide not to send an OLR with a validity duration of zero. decide not to send an OLR with a validity duration of zero.
A reporting node MUST keep an OCS entry with a validity duration of A reporting node MUST keep an OCS entry with a validity duration of
zero ("0") for a period of time long enough to ensure that any non- zero ("0") for a period of time long enough to ensure that any non-
expired reacting node's OCS entry created as a result of the overload expired reacting node's OCS entry created as a result of the overload
condition in the reporting node is deleted. condition in the reporting node is deleted.
4.2.2. Reacting Node Behavior 5.2.2. Reacting Node Behavior
When a reacting node sends a request it MUST determine if that When a reacting node sends a request it MUST determine if that
request matches an active OCS. request matches an active OCS.
If the request matches an active OCS then the reacting node MUST use If the request matches an active OCS then the reacting node MUST use
the overload abatement algorithm indicated in the OCS to determine if the overload abatement algorithm indicated in the OCS to determine if
the request is to receive overload abatement treatment. the request is to receive overload abatement treatment.
For the Loss abatement algorithm defined in this specification, see For the Loss abatement algorithm defined in this specification, see
Section 5 for the overload abatement algorithm logic applied. Section 6 for the overload abatement algorithm logic applied.
If the overload abatement algorithm selects the request for overload If the overload abatement algorithm selects the request for overload
abatement treatment then the reacting node MUST apply overload abatement treatment then the reacting node MUST apply overload
abatement treatment on the request. The abatement treatment applied abatement treatment on the request. The abatement treatment applied
depends on the context of the request. depends on the context of the request.
If the request is a host-routed request then the reacting node SHOULD If diversion abatement treatment is possible (i.e. a different path
apply throttling abatement treatment to the request. for the request can be selected where the overloaded node is not part
of the different path), then the reacting node SHOULD apply diversion
If the request is a realm-routed request then the reacting node abatement treatment to the request. Otherwise the reacting node
SHOULD apply diversion abatement treatment to the request. SHOULD apply throttling abatement treatment to the request.
If the overload abatement treatment results in throttling of the If the overload abatement treatment results in throttling of the
request and if the reacting node is an agent then the agent MUST send request and if the reacting node is an agent then the agent MUST send
an appropriate error as defined in Section 7. an appropriate error as defined in Section 8.
The behavior of reacting nodes that are Diameter endpoints when Diameter endpoints that throttle requests need to do so according to
throttling requests depends on the application and is outside the the rules of the client application. Those rules will vary by
scope of this specification. application, and are beyond the scope of this document.
In the case that the OCS entry indicated no traffic was to be sent to In the case that the OCS entry indicated no traffic was to be sent to
the overloaded entity and the validity duration expires or has a the overloaded entity and the validity duration expires then overload
validity duration of zero ("0"), meaning that the reporting node has abatement associated with the overload report MUST be ended in a
explicitly signaled the end of the overload condition then overload
abatement associated with the overload abatement MUST be ended in a
controlled fashion. controlled fashion.
4.2.3. Reporting Node Behavior 5.2.3. Reporting Node Behavior
If there is an active OCS entry then a reporting node SHOULD include If there is an active OCS entry then a reporting node SHOULD include
the OC-OLR AVP in all answer messages to requests that contain the the OC-OLR AVP in all answers to requests that contain the OC-
OC-Supported-Features AVP and that match the active OCS entry. Supported-Features AVP and that match the active OCS entry.
Note: A request matches if the application-id in the request Note: A request matches if the application-id in the request
matches the application-id in any active OCS entry and if the matches the application-id in any active OCS entry and if the
report-type in the OCS entry matches a report-type supported by report-type in the OCS entry matches a report-type supported by
the reporting node as indicated in the OC-Supported-Features AVP. the reporting node as indicated in the OC-Supported-Features AVP.
The contents of the OC-OLR AVP depend on the selected algorithm. The contents of the OC-OLR AVP depend on the selected algorithm.
A reporting node MAY choose to not resend an overload report to a A reporting node MAY choose to not resend an overload report to a
reacting node if it can guarantee that this overload report is reacting node if it can guarantee that this overload report is
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report. report.
A reporting node MUST NOT send overload reports of a type that has A reporting node MUST NOT send overload reports of a type that has
not been advertised as supported by the reacting node. not been advertised as supported by the reacting node.
Note: A reacting node implicitly advertises support for the host Note: A reacting node implicitly advertises support for the host
and realm report types by including the OC-Supported-Features AVP and realm report types by including the OC-Supported-Features AVP
in the request. Support for other report types will be explicitly in the request. Support for other report types will be explicitly
indicated by new feature bits in the OC-Feature-Vector AVP. indicated by new feature bits in the OC-Feature-Vector AVP.
A reporting node MAY rely on the OC-Validity-Duration AVP values for
the implicit overload control state cleanup on the reacting node.
A reporting node SHOULD explicitly indicate the end of an overload A reporting node SHOULD explicitly indicate the end of an overload
occurrence by sending a new OLR with OC-Validity-Duration set to a occurrence by sending a new OLR with OC-Validity-Duration set to a
value of zero ("0"). The reporting node SHOULD ensure that all value of zero ("0"). The reporting node SHOULD ensure that all
reacting nodes receive the updated overload report. reacting nodes receive the updated overload report.
A reporting node MAY rely on the OC-Validity-Duration AVP values for
the implicit overload control state cleanup on the reacting node.
Note: All OLRs sent have an expiration time calculated by adding Note: All OLRs sent have an expiration time calculated by adding
the validity-duration contained in the OLR to the time the message the validity-duration contained in the OLR to the time the message
was sent. Transit time for the OLR can be safely ignored. The was sent. Transit time for the OLR can be safely ignored. The
reporting node can ensure that all reacting nodes have received reporting node can ensure that all reacting nodes have received
the OLR by continuing to send it in answer messages until the the OLR by continuing to send it in answer messages until the
expiration time for all OLRs sent for that overload condition have expiration time for all OLRs sent for that overload condition have
expired. expired.
When a reporting node sends an OLR, it effectively delegates any When a reporting node sends an OLR, it effectively delegates any
necessary throttling to downstream nodes. If the reporting node also necessary throttling to downstream nodes. If the reporting node also
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for reasons other than overload. For example, an agent or server for reasons other than overload. For example, an agent or server
might have a configured rate limit for each client, and throttle might have a configured rate limit for each client, and throttle
requests that exceed that limit, even if such requests had already requests that exceed that limit, even if such requests had already
been candidates for throttling by downstream nodes. The reporting been candidates for throttling by downstream nodes. The reporting
node also has the option to send new OLRs requesting greater node also has the option to send new OLRs requesting greater
reductions in traffic, reducing the need for local throttling. reductions in traffic, reducing the need for local throttling.
A reporting node SHOULD decrease requested overload abatement A reporting node SHOULD decrease requested overload abatement
treatment in a controlled fashion to avoid oscillations in traffic. treatment in a controlled fashion to avoid oscillations in traffic.
4.3. Protocol Extensibility For example, it might wait some period of time after overload ends
before terminating the OLR, or it might send a series of OLRs
indicating progressively less overload severity.
5.3. Protocol Extensibility
The DOIC solution can be extended. Types of potential extensions The DOIC solution can be extended. Types of potential extensions
include new traffic abatement algorithms, new report types or other include new traffic abatement algorithms, new report types or other
new functionality. new functionality.
When defining a new extension that requires new normative behavior, When defining a new extension that requires new normative behavior,
the specification MUST define a new feature for the OC-Feature- the specification MUST define a new feature for the OC-Feature-
Vector. This feature bit is used to communicate support for the new Vector. This feature bit is used to communicate support for the new
feature. feature.
The extension MAY define new AVPs for use in DOIC Capability The extension MAY define new AVPs for use in DOIC Capability
Announcement and for use in DOIC Overload reporting. These new AVPs Announcement and for use in DOIC Overload reporting. These new AVPs
SHOULD be defined to be extensions to the OC-Supported-Features and SHOULD be defined to be extensions to the OC-Supported-Features or
OC-OLR AVPs defined in this document. OC-OLR AVPs defined in this document.
[RFC6733] defined Grouped AVP extension mechanisms apply. This [RFC6733] defined Grouped AVP extension mechanisms apply. This
allows, for example, defining a new feature that is mandatory to be allows, for example, defining a new feature that is mandatory to be
understood even when piggybacked on an existing application. understood even when piggybacked on an existing application.
The handling of feature bits in the OC-Feature-Vector AVP that are
not associated with overload abatement algorithms MUST be specified
by the extensions that define the features.
When defining new report type values, the corresponding specification When defining new report type values, the corresponding specification
MUST define the semantics of the new report types and how they affect MUST define the semantics of the new report types and how they affect
the OC-OLR AVP handling. The specification MUST also reserve a the OC-OLR AVP handling.
corresponding new feature bit in the OC-Feature-Vector AVP.
The OC-OLR AVP can be expanded with optional sub-AVPs only if a The OC-OLR AVP can be expanded with optional sub-AVPs only if a
legacy DOIC implementation can safely ignore them without breaking legacy DOIC implementation can safely ignore them without breaking
backward compatibility for the given OC-Report-Type AVP value. If backward compatibility for the given OC-Report-Type AVP value.
the new sub-AVPs imply new semantics for handling the indicated
report type, then a new OC-Report-Type AVP value MUST be defined.
Documents that introduce new report types MUST describe any Documents that introduce new report types MUST describe any
limitations on their use across non-supporting agents. limitations on their use across non-supporting agents.
As with any Diameter specification, RFC6733 requires all new AVPs to
be registered with IANA. See Section 9 for the required procedures.
New features (feature bits in the OC-Feature-Vector AVP) and report New features (feature bits in the OC-Feature-Vector AVP) and report
types (in the OC-Report-Type AVP) MUST be registered with IANA. As types (in the OC-Report-Type AVP) MUST be registered with IANA.
with any Diameter specification, RFC6733 requires all new AVPs to be
registered with IANA. See Section 8 for the required procedures.
5. Loss Algorithm 6. Loss Algorithm
This section documents the Diameter overload loss abatement This section documents the Diameter overload loss abatement
algorithm. algorithm.
5.1. Overview 6.1. Overview
The DOIC specification supports the ability for multiple overload The DOIC specification supports the ability for multiple overload
abatement algorithms to be specified. The abatement algorithm used abatement algorithms to be specified. The abatement algorithm used
for any instance of overload is determined by the Diameter Overload for any instance of overload is determined by the Diameter Overload
Capability Announcement process documented in Section 4.1. Capability Announcement process documented in Section 5.1.
The loss algorithm described in this section is the default algorithm The loss algorithm described in this section is the default algorithm
that must be supported by all Diameter nodes that support DOIC. that must be supported by all Diameter nodes that support DOIC.
The loss algorithm is designed to be a straightforward and stateless The loss algorithm is designed to be a straightforward and stateless
overload abatement algorithm. It is used by reporting nodes to overload abatement algorithm. It is used by reporting nodes to
request a percentage reduction in the amount of traffic sent. The request a percentage reduction in the amount of traffic sent. The
traffic impacted by the requested reduction depends on the type of traffic impacted by the requested reduction depends on the type of
overload report. overload report.
Reporting nodes use a strategy of applying abatement logic to the Reporting nodes request the stateless reduction of the number of
requested percentage of request messages sent (or handled in the case requests by an indicated percentage. This percentage reduction is in
of agents) by the reacting node that are impacted by the overload comparison to the number of messages the node otherwise would send,
report. regardless of how many requests the node might have sent in the past.
From a conceptual level, the logic at the reacting node could be From a conceptual level, the logic at the reacting node could be
outlined as follows. outlined as follows.
1. An overload report is received and the associated OCS is either 1. An overload report is received and the associated OCS is either
saved or updated (if required) by the reacting node. saved or updated (if required) by the reacting node.
2. A new Diameter request is generated by the application running on 2. A new Diameter request is generated by the application running on
the reacting node. the reacting node.
3. The reacting node determines that an active overload report 3. The reacting node determines that an active overload report
applies to the request, as indicated by the corresponding OCS applies to the request, as indicated by the corresponding OCS
entry. entry.
4. The reacting node determines if overload abatement treatment 4. The reacting node determines if overload abatement treatment
should be applied to the request. One approach that could be should be applied to the request. One approach that could be
taken for each request is to select a random number between 1 and taken for each request is to select a random number between 1 and
100. If the random number is less than the indicated reduction 100. If the random number is less than or equal to the indicated
percentage then the request is given abatement treatment, reduction percentage then the request is given abatement
otherwise the request is given normal routing treatment. treatment, otherwise the request is given normal routing
treatment.
5.2. Reporting Node Behavior 6.2. Reporting Node Behavior
The method a reporting node uses to determine the amount of traffic The method a reporting node uses to determine the amount of traffic
reduction required to address an overload condition is an reduction required to address an overload condition is an
implementation decision. implementation decision.
When a reporting node that has selected the loss abatement algorithm When a reporting node that has selected the loss abatement algorithm
determines the need to request a reduction in traffic, it includes an determines the need to request a reduction in traffic, it includes an
OC-OLR AVP in response messages as described in Section 4.2.3. OC-OLR AVP in answer messages as described in Section 5.2.3.
When sending the OC-OLR AVP, the reporting node MUST indicate a When sending the OC-OLR AVP, the reporting node MUST indicate a
percentage reduction in the OC-Reduction-Percentage AVP. percentage reduction in the OC-Reduction-Percentage AVP.
The reporting node MAY change the reduction percentage in subsequent The reporting node MAY change the reduction percentage in subsequent
overload reports. When doing so the reporting node must conform to overload reports. When doing so the reporting node must conform to
overload report handing specified in Section 4.2.3. overload report handing specified in Section 5.2.3.
5.3. Reacting Node Behavior 6.3. Reacting Node Behavior
The method a reacting node uses to determine which request messages The method a reacting node uses to determine which request messages
are given abatement treatment is an implementation decision. are given abatement treatment is an implementation decision.
When receiving an OC-OLR in an answer message where the algorithm When receiving an OC-OLR in an answer message where the algorithm
indicated in the OC-Supported-Features AVP is the loss algorithm, the indicated in the OC-Supported-Features AVP is the loss algorithm, the
reacting node MUST apply abatement treatment to the requested reacting node MUST apply abatement treatment to the requested
percentage of request messages sent. percentage of request messages sent.
Note: The loss algorithm is a stateless algorithm. As a result, Note: The loss algorithm is a stateless algorithm. As a result,
the reacting node does not guarantee that there will be an the reacting node does not guarantee that there will be an
absolute reduction in traffic sent. Rather, it guarantees that absolute reduction in traffic sent. Rather, it guarantees that
the requested percentage of new requests will be given abatement the requested percentage of new requests will be given abatement
treatment. treatment.
When applying overload abatement treatment for the load abatement When applying overload abatement treatment for the loss abatement
algorithm, the reacting node MUST abate the requested percentage of algorithm, the reacting node MUST abate the requested percentage of
requests that would have otherwise been sent to the reporting host or requests that would have otherwise been sent to the reporting host or
realm. realm.
If reacting node comes out of the 100 percent traffic reduction as a If reacting node comes out of the 100 percent traffic reduction as a
result of the overload report timing out, the following concerns are result of the overload report timing out, the following procedures
RECOMMENDED to be applied. The reacting node sending the traffic are RECOMMENDED to be applied. The reacting node sending the traffic
should be conservative and, for example, first send "probe" messages should be conservative and, for example, first send "probe" messages
to learn the overload condition of the overloaded node before to learn the overload condition of the overloaded node before
converging to any traffic amount/rate decided by the sender. Similar converging to any traffic amount/rate decided by the sender. Similar
concerns apply in all cases when the overload report times out unless concerns apply in all cases when the overload report times out unless
the previous overload report stated 0 percent reduction. the previous overload report stated 0 percent reduction.
If the reacting node does not receive an OLR in messages sent to the
formerly overloaded node then the reacting node SHOULD slowly
increase the rate of traffic sent to the overloaded node.
When an active overload report expires, it is suggested that the
reacting node progressively decrease the amount of traffic given
abatement treatment, until the reduction is completely removed and no
traffic is given abatement treatment.
The goal of this behavior is to reduce the probability of overload The goal of this behavior is to reduce the probability of overload
condition thrashing where an immediate transition from 100% condition thrashing where an immediate transition from 100%
reduction to 0% reduction results in the reporting node moving reduction to 0% reduction results in the reporting node moving
quickly back into an overload condition. quickly back into an overload condition.
6. Attribute Value Pairs If the reacting node does not receive an OLR in answers received from
the formerly overloaded node then the reacting node SHOULD slowly
increase the rate of traffic sent to the overloaded node.
7. Attribute Value Pairs
This section describes the encoding and semantics of the Diameter This section describes the encoding and semantics of the Diameter
Overload Indication Attribute Value Pairs (AVPs) defined in this Overload Indication Attribute Value Pairs (AVPs) defined in this
document. document.
A new application specification can incorporate the overload control 7.1. OC-Supported-Features AVP
mechanism specified in this document by making it mandatory to
implement for the application and referencing this specification
normatively. It is the responsibility of the Diameter application
designers to define how overload control mechanisms works on that
application.
6.1. OC-Supported-Features AVP
The OC-Supported-Features AVP (AVP code TBD1) is of type Grouped and The OC-Supported-Features AVP (AVP code TBD1) is of type Grouped and
serves two purposes. First, it announces a node's support for the serves two purposes. First, it announces a node's support for the
DOIC solution in general. Second, it contains the description of the DOIC solution in general. Second, it contains the description of the
supported DOIC features of the sending node. The OC-Supported- supported DOIC features of the sending node. The OC-Supported-
Features AVP MUST be included in every Diameter request message a Features AVP MUST be included in every Diameter request message a
DOIC supporting node sends. DOIC supporting node sends.
OC-Supported-Features ::= < AVP Header: TBD1 > OC-Supported-Features ::= < AVP Header: TBD1 >
[ OC-Feature-Vector ] [ OC-Feature-Vector ]
* [ AVP ] * [ AVP ]
The OC-Feature-Vector sub-AVP is used to announce the DOIC features 7.2. OC-Feature-Vector AVP
supported by the DOIC node, in the form of a flag-bits field in which
each bit announces one feature or capability supported by the node
(see Section 6.2). The absence of the OC-Feature-Vector AVP
indicates that only the default traffic abatement algorithm described
in this specification is supported.
6.2. OC-Feature-Vector AVP
The OC-Feature-Vector AVP (AVP code TBD6) is of type Unsigned64 and The OC-Feature-Vector AVP (AVP code TBD2) is of type Unsigned64 and
contains a 64 bit flags field of announced capabilities of a DOIC contains a 64 bit flags field of announced capabilities of a DOIC
node. The value of zero (0) is reserved. node. The value of zero (0) is reserved.
The OC-Feature-Vector sub-AVP is used to announce the DOIC features The OC-Feature-Vector sub-AVP is used to announce the DOIC features
supported by the DOIC node, in the form of a flag-bits field in which supported by the DOIC node, in the form of a flag-bits field in which
each bit announces one feature or capability supported by the node each bit announces one feature or capability supported by the node.
(see Section 6.2). The absence of the OC-Feature-Vector AVP The absence of the OC-Feature-Vector AVP in request messages
indicates that only the default traffic abatement algorithm described indicates that only the default traffic abatement algorithm described
in this specification is supported. in this specification is supported. The absence of the OC- Feature-
Vector AVP in answer messages indicates that the default traffic
abatement algorithm described in this specification is selected
(while other traffic abatement algorithms may be supported), and no
features other than abatement algorithms are supported.
The following capabilities are defined in this document: The following capabilities are defined in this document:
OLR_DEFAULT_ALGO (0x0000000000000001) OLR_DEFAULT_ALGO (0x0000000000000001)
When this flag is set by the a DOIC reacting node it means that When this flag is set by the a DOIC reacting node it means that
the default traffic abatement (loss) algorithm is supported. When the default traffic abatement (loss) algorithm is supported. When
this flag is set by a DOIC reporting node it means that the loss this flag is set by a DOIC reporting node it means that the loss
algorithm will be used for requested overload abatement. algorithm will be used for requested overload abatement.
6.3. OC-OLR AVP 7.3. OC-OLR AVP
The OC-OLR AVP (AVP code TBD2) is of type Grouped and contains the The OC-OLR AVP (AVP code TBD3) is of type Grouped and contains the
information necessary to convey an overload report on an overload information necessary to convey an overload report on an overload
condition at the reporting node. The OC-OLR AVP does not explicitly condition at the reporting node. The application the OC-OLR AVP
contain all information needed by the reacting node to decide whether applies to is the same as the Application-Id found in the Diameter
a subsequent request must undergo abatement using the received message header. The host or realm the OC-OLR AVP concerns is
reduction percentage. The value of the OC-Report-Type AVP within the determined from the Origin-Host AVP and/or Origin-Realm AVP found in
OC-OLR AVP indicates which implicit information is relevant for this the encapsulating Diameter command. The OC-OLR AVP is intended to be
decision (see Section 6.6). The application the OC-OLR AVP applies
to is the same as the Application-Id found in the Diameter message
header. The host or realm the OC-OLR AVP concerns is determined from
the Origin-Host AVP and/or Origin-Realm AVP found in the
encapsulating Diameter command. The OC-OLR AVP is intended to be
sent only by a reporting node. sent only by a reporting node.
OC-OLR ::= < AVP Header: TBD2 > OC-OLR ::= < AVP Header: TBD2 >
< OC-Sequence-Number > < OC-Sequence-Number >
< OC-Report-Type > < OC-Report-Type >
[ OC-Reduction-Percentage ] [ OC-Reduction-Percentage ]
[ OC-Validity-Duration ] [ OC-Validity-Duration ]
* [ AVP ] * [ AVP ]
6.4. OC-Sequence-Number AVP 7.4. OC-Sequence-Number AVP
The OC-Sequence-Number AVP (AVP code TBD3) is of type Unsigned64. The OC-Sequence-Number AVP (AVP code TBD4) is of type Unsigned64.
Its usage in the context of overload control is described in Its usage in the context of overload control is described in
Section 4.2. Section 5.2.
From the functionality point of view, the OC-Sequence-Number AVP is From the functionality point of view, the OC-Sequence-Number AVP is
used as a non-volatile increasing counter for a sequence of overload used as a non-volatile increasing counter for a sequence of overload
reports between two DOIC nodes for the same overload occurrence. The reports between two DOIC nodes for the same overload occurrence.
sequence number is only required to be unique between two DOIC nodes.
Sequence numbers are treated in a uni-directional manner, i.e. two Sequence numbers are treated in a uni-directional manner, i.e. two
sequence numbers on each direction between two DOIC nodes are not sequence numbers on each direction between two DOIC nodes are not
related or correlated. related or correlated.
6.5. OC-Validity-Duration AVP 7.5. OC-Validity-Duration AVP
The OC-Validity-Duration AVP (AVP code TBD4) is of type Unsigned32 The OC-Validity-Duration AVP (AVP code TBD5) is of type Unsigned32
and indicates in milliseconds the validity time of the overload and indicates in seconds the validity time of the overload report.
report. The number of milliseconds is measured after reception of The number of mseconds is measured after reception of the first OC-
the first OC-OLR AVP with a given value of OC-Sequence-Number AVP. OLR AVP with a given value of OC-Sequence-Number AVP. The default
The default value for the OC-Validity-Duration AVP is 30000 (i.e.; 30 value for the OC-Validity-Duration AVP is 30 seconds. When the OC-
seconds). When the OC-Validity-Duration AVP is not present in the Validity-Duration AVP is not present in the OC-OLR AVP, the default
OC-OLR AVP, the default value applies. value applies. The maximum value for the OC-Validity-Duration AVP is
86,400 seconds (24 hours).
6.6. OC-Report-Type AVP 7.6. OC-Report-Type AVP
The OC-Report-Type AVP (AVP code TBD5) is of type Enumerated. The The OC-Report-Type AVP (AVP code TBD6) is of type Enumerated. The
value of the AVP describes what the overload report concerns. The value of the AVP describes what the overload report concerns. The
following values are initially defined: following values are initially defined:
HOST_REPORT 0 The overload report is for a host. Overload abatement HOST_REPORT 0 The overload report is for a host. Overload abatement
treatment applies to host-routed requests. treatment applies to host-routed requests.
REALM_REPORT 1 The overload report is for a realm. Overload REALM_REPORT 1 The overload report is for a realm. Overload
abatement treatment applies to realm-routed requests. abatement treatment applies to realm-routed requests.
6.7. OC-Reduction-Percentage AVP 7.7. OC-Reduction-Percentage AVP
The OC-Reduction-Percentage AVP (AVP code TBD8) is of type Unsigned32 The OC-Reduction-Percentage AVP (AVP code TBD7) is of type Unsigned32
and describes the percentage of the traffic that the sender is and describes the percentage of the traffic that the sender is
requested to reduce, compared to what it otherwise would send. The requested to reduce, compared to what it otherwise would send. The
OC-Reduction-Percentage AVP applies to the default (loss) algorithm OC-Reduction-Percentage AVP applies to the default (loss) algorithm
specified in this specification. However, the AVP can be reused for specified in this specification. However, the AVP can be reused for
future abatement algorithms, if its semantics fit into the new future abatement algorithms, if its semantics fit into the new
algorithm. algorithm.
The value of the Reduction-Percentage AVP is between zero (0) and one The value of the Reduction-Percentage AVP is between zero (0) and one
hundred (100). Values greater than 100 are ignored. The value of hundred (100). Values greater than 100 are ignored. The value of
100 means that all traffic is to be throttled, i.e. the reporting 100 means that all traffic is to be throttled, i.e. the reporting
node is under a severe load and ceases to process any new messages. node is under a severe load and ceases to process any new messages.
The value of 0 means that the reporting node is in a stable state and The value of 0 means that the reporting node is in a stable state and
has no need for the reacting node to apply any traffic abatement. has no need for the reacting node to apply any traffic abatement.
The default value of the OC-Reduction-Percentage AVP is 0. When the
OC-Reduction-Percentage AVP is not present in the overload report,
the default value applies.
6.8. Attribute Value Pair flag rules 7.8. Attribute Value Pair flag rules
+---------+ +---------+
|AVP flag | |AVP flag |
|rules | |rules |
+----+----+ +----+----+
AVP Section | |MUST| AVP Section | |MUST|
Attribute Name Code Defined Value Type |MUST| NOT| Attribute Name Code Defined Value Type |MUST| NOT|
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Supported-Features TBD1 6.1 Grouped | | V | |OC-Supported-Features TBD1 6.1 Grouped | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-OLR TBD2 6.3 Grouped | | V | |OC-Feature-Vector TBD2 6.2 Unsigned64 | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Sequence-Number TBD3 6.4 Unsigned64 | | V | |OC-OLR TBD3 6.3 Grouped | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Validity-Duration TBD4 6.5 Unsigned32 | | V | |OC-Sequence-Number TBD4 6.4 Unsigned64 | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Report-Type TBD5 6.6 Enumerated | | V | |OC-Validity-Duration TBD5 6.5 Unsigned32 | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Reduction | | | |OC-Report-Type TBD6 6.6 Enumerated | | V |
| -Percentage TBD8 6.7 Unsigned32 | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
|OC-Feature-Vector TBD6 6.2 Unsigned64 | | V | |OC-Reduction | | |
| -Percentage TBD7 6.7 Unsigned32 | | V |
+--------------------------------------------------+----+----+ +--------------------------------------------------+----+----+
As described in the Diameter base protocol [RFC6733], the M-bit usage As described in the Diameter base protocol [RFC6733], the M-bit usage
for a given AVP in a given command may be defined by the for a given AVP in a given command may be defined by the application.
application..
7. Error Response Codes 8. Error Response Codes
When a DOIC node rejects a Diameter request due to overload, the DOIC When a DOIC node rejects a Diameter request due to overload, the DOIC
node MUST select an appropriate error response code. This node MUST select an appropriate error response code. This
determination is made based on the probability of the request determination is made based on the probability of the request
succeeding if retried on a different path. succeeding if retried on a different path.
A reporting node rejecting a Diameter request due to an overload A reporting node rejecting a Diameter request due to an overload
condition SHOULD send a DIAMETER-TOO-BUSY error response, if it can condition SHOULD send a DIAMETER_TOO_BUSY error response, if it can
assume that the same request may succeed on a different path. assume that the same request may succeed on a different path.
If a reporting node knows or assumes that the same request will not If a reporting node knows or assumes that the same request will not
succeed on a different path, DIAMETER_UNABLE_TO_COMPLY error response succeed on a different path, DIAMETER_UNABLE_TO_COMPLY error response
SHOULD be used. Retrying would consume valuable resources during an SHOULD be used. Retrying would consume valuable resources during an
occurrence of overload. occurrence of overload.
For instance, if the request arrived at the reporting node without For instance, if the request arrived at the reporting node without
a Destination-Host AVP then the reporting node might determine a Destination-Host AVP then the reporting node might determine
that there is an alternative Diameter node that could successfully that there is an alternative Diameter node that could successfully
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reporting node can assume that retrying the request would result reporting node can assume that retrying the request would result
in it coming to the same reporting node. in it coming to the same reporting node.
DIAMETER_UNABLE_TO_COMPLY would be sent in this case. DIAMETER_UNABLE_TO_COMPLY would be sent in this case.
A second example is when an agent that supports the DOIC solution A second example is when an agent that supports the DOIC solution
is performing the role of a reacting node for a non supporting is performing the role of a reacting node for a non supporting
client. Requests that are rejected as a result of DOIC throttling client. Requests that are rejected as a result of DOIC throttling
by the agent in this scenario would generally be rejected with a by the agent in this scenario would generally be rejected with a
DIAMETER_UNABLE_TO_COMPLY response code. DIAMETER_UNABLE_TO_COMPLY response code.
8. IANA Considerations 9. IANA Considerations
8.1. AVP codes 9.1. AVP codes
New AVPs defined by this specification are listed in Section 6. All New AVPs defined by this specification are listed in Section 7. All
AVP codes are allocated from the 'Authentication, Authorization, and AVP codes are allocated from the 'Authentication, Authorization, and
Accounting (AAA) Parameters' AVP Codes registry. Accounting (AAA) Parameters' AVP Codes registry.
8.2. New registries 9.2. New registries
Two new registries are needed under the 'Authentication, Two new registries are needed under the 'Authentication,
Authorization, and Accounting (AAA) Parameters' registry. Authorization, and Accounting (AAA) Parameters' registry.
A new "Overload Control Feature Vector" registry is required. The A new "Overload Control Feature Vector" registry is required. The
registry must contain the following: registry must contain the following:
Feature Vector Value Feature Vector Value
Specification - the specification that defines the new value. Specification - the specification that defines the new value.
See Section 6.2 for the initial Feature Vector Value in the registry. See Section 7.2 for the initial Feature Vector Value in the registry.
This specification is the specification defining the value. New This specification is the specification defining the value. New
values can be added into the registry using the Specification values can be added into the registry using the Specification
Required policy. [RFC5226]. Required policy. [RFC5226].
A new "Overload Report Type" registry is required. The registry must A new "Overload Report Type" registry is required. The registry must
contain the following: contain the following:
Report Type Value Report Type Value
Specification - the specification that defines the new value. Specification - the specification that defines the new value.
See Section 6.2 for the initial assignment in the registry. New See Section 7.6 for the initial assignment in the registry. New
types can be added using the Specification Required policy [RFC5226]. types can be added using the Specification Required policy [RFC5226].
9. Security Considerations 10. Security Considerations
DOIC gives Diameter nodes the ability to request that downstream DOIC gives Diameter nodes the ability to request that downstream
nodes send fewer Diameter requests. Nodes do this by exchanging nodes send fewer Diameter requests. Nodes do this by exchanging
overload reports that directly effect this reduction. This exchange overload reports that directly effect this reduction. This exchange
is potentially subject to multiple methods of attack, and has the is potentially subject to multiple methods of attack, and has the
potential to be used as a Denial-of-Service (DoS) attack vector. potential to be used as a Denial-of-Service (DoS) attack vector.
Overload reports may contain information about the topology and Overload reports may contain information about the topology and
current status of a Diameter network. This information is current status of a Diameter network. This information is
potentially sensitive. Network operators may wish to control potentially sensitive. Network operators may wish to control
disclosure of overload reports to unauthorized parties to avoid its disclosure of overload reports to unauthorized parties to avoid its
use for competitive intelligence or to target attacks. use for competitive intelligence or to target attacks.
Diameter does not include features to provide end-to-end Diameter does not include features to provide end-to-end
authentication, integrity protection, or confidentiality. This may authentication, integrity protection, or confidentiality. This may
cause complications when sending overload reports between non- cause complications when sending overload reports between non-
adjacent nodes. adjacent nodes.
9.1. Potential Threat Modes 10.1. Potential Threat Modes
The Diameter protocol involves transactions in the form of requests The Diameter protocol involves transactions in the form of requests
and answers exchanged between clients and servers. These clients and and answers exchanged between clients and servers. These clients and
servers may be peers, that is, they may share a direct transport servers may be peers, that is, they may share a direct transport
(e.g. TCP or SCTP) connection, or the messages may traverse one or (e.g. TCP or SCTP) connection, or the messages may traverse one or
more intermediaries, known as Diameter Agents. Diameter nodes use more intermediaries, known as Diameter Agents. Diameter nodes use
TLS, DTLS, or IPsec to authenticate peers, and to provide TLS, DTLS, or IPsec to authenticate peers, and to provide
confidentiality and integrity protection of traffic between peers. confidentiality and integrity protection of traffic between peers.
Nodes can make authorization decisions based on the peer identities Nodes can make authorization decisions based on the peer identities
authenticated at the transport layer. authenticated at the transport layer.
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before acting on the report or forwarding the report to other peers. before acting on the report or forwarding the report to other peers.
For example, an overload report from a peer that applies to a realm For example, an overload report from a peer that applies to a realm
not handled by that peer is suspect. not handled by that peer is suspect.
This attack is partially mitigated by the fact that the This attack is partially mitigated by the fact that the
application, as well as host and realm, for a given OLR is application, as well as host and realm, for a given OLR is
determined implicitly by respective AVPs in the enclosing answer. determined implicitly by respective AVPs in the enclosing answer.
If a reporting node modifies any of those AVPs, the enclosing If a reporting node modifies any of those AVPs, the enclosing
transaction will also be affected. transaction will also be affected.
9.2. Denial of Service Attacks 10.2. Denial of Service Attacks
Diameter overload reports, especially realm-reports, can cause a node Diameter overload reports, especially realm-reports, can cause a node
to cease sending some or all Diameter requests for an extended to cease sending some or all Diameter requests for an extended
period. This makes them a tempting vector for DoS attacks. period. This makes them a tempting vector for DoS attacks.
Furthermore, since Diameter is almost always used in support of other Furthermore, since Diameter is almost always used in support of other
protocols, a DoS attack on Diameter is likely to impact those protocols, a DoS attack on Diameter is likely to impact those
protocols as well. Therefore, Diameter nodes MUST NOT honor or protocols as well. Therefore, Diameter nodes MUST NOT honor or
forward OLRs received from peers that are not trusted to send them. forward OLRs received from peers that are not trusted to send them.
An attacker might use the information in an OLR to assist in DoS An attacker might use the information in an OLR to assist in DoS
attacks. For example, an attacker could use information about attacks. For example, an attacker could use information about
current overload conditions to time an attack for maximum effect, or current overload conditions to time an attack for maximum effect, or
use subsequent overload reports as a feedback mechanism to learn the use subsequent overload reports as a feedback mechanism to learn the
results of a previous or ongoing attack. Operators need the ability results of a previous or ongoing attack. Operators need the ability
to ensure that OLRs are not leaked to untrusted parties. to ensure that OLRs are not leaked to untrusted parties.
9.3. Non-Compliant Nodes 10.3. Non-Compliant Nodes
In the absence of an overload control mechanism, Diameter nodes need In the absence of an overload control mechanism, Diameter nodes need
to implement strategies to protect themselves from floods of to implement strategies to protect themselves from floods of
requests, and to make sure that a disproportionate load from one requests, and to make sure that a disproportionate load from one
source does not prevent other sources from receiving service. For source does not prevent other sources from receiving service. For
example, a Diameter server might throttle a certain percentage of example, a Diameter server might throttle a certain percentage of
requests from sources that exceed certain limits. Overload control requests from sources that exceed certain limits. Overload control
can be thought of as an optimization for such strategies, where can be thought of as an optimization for such strategies, where
downstream nodes never send the excess requests in the first place. downstream nodes never send the excess requests in the first place.
However, the presence of an overload control mechanism does not However, the presence of an overload control mechanism does not
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When a Diameter node sends an overload report, it cannot assume that When a Diameter node sends an overload report, it cannot assume that
all nodes will comply, even if they indicate support for DOIC. A all nodes will comply, even if they indicate support for DOIC. A
non-compliant node might continue to send requests with no reduction non-compliant node might continue to send requests with no reduction
in load. Such non-compliance could be done accidentally, or in load. Such non-compliance could be done accidentally, or
maliciously to gain an unfair advantage over compliant nodes. maliciously to gain an unfair advantage over compliant nodes.
Requirement 28 [RFC7068] indicates that the overload control solution Requirement 28 [RFC7068] indicates that the overload control solution
cannot assume that all Diameter nodes in a network are trusted, and cannot assume that all Diameter nodes in a network are trusted, and
that malicious nodes not be allowed to take advantage of the overload that malicious nodes not be allowed to take advantage of the overload
control mechanism to get more than their fair share of service. control mechanism to get more than their fair share of service.
9.4. End-to End-Security Issues 10.4. End-to End-Security Issues
The lack of end-to-end integrity features makes it difficult to The lack of end-to-end integrity features makes it difficult to
establish trust in overload reports received from non-adjacent nodes. establish trust in overload reports received from non-adjacent nodes.
Any agents in the message path may insert or modify overload reports. Any agents in the message path may insert or modify overload reports.
Nodes must trust that their adjacent peers perform proper checks on Nodes must trust that their adjacent peers perform proper checks on
overload reports from their peers, and so on, creating a transitive- overload reports from their peers, and so on, creating a transitive-
trust requirement extending for potentially long chains of nodes. trust requirement extending for potentially long chains of nodes.
Network operators must determine if this transitive trust requirement Network operators must determine if this transitive trust requirement
is acceptable for their deployments. Nodes supporting Diameter is acceptable for their deployments. Nodes supporting Diameter
overload control MUST give operators the ability to select which overload control MUST give operators the ability to select which
peers are trusted to deliver overload reports, and whether they are peers are trusted to deliver overload reports, and whether they are
trusted to forward overload reports from non-adjacent nodes. DOIC trusted to forward overload reports from non-adjacent nodes. DOIC
nodes MUST strip DOIC AVPs from messages received from peers that are nodes MUST strip DOIC AVPs from messages received from peers that are
not trusted for DOIC purposes. not trusted for DOIC purposes.
The lack of end-to-end confidentiality protection means that any The lack of end-to-end confidentiality protection means that any
Diameter agent in the path of an overload report can view the Diameter agent in the path of an overload report can view the
contents of that report. In addition to the requirement to select contents of that report. In addition to the requirement to select
which peers are trusted to send overload reports, operators MUST be which peers are trusted to send overload reports, operators MUST be
able to select which peers are authorized to receive reports. A node able to select which peers are authorized to receive reports. A node
MUST not send an overload report to a peer not authorized to receive MUST NOT send an overload report to a peer not authorized to receive
it. Furthermore, an agent MUST remove any overload reports that it. Furthermore, an agent MUST remove any overload reports that
might have been inserted by other nodes before forwarding a Diameter might have been inserted by other nodes before forwarding a Diameter
message to a peer that is not authorized to receive overload reports. message to a peer that is not authorized to receive overload reports.
A DOIC node cannot always automatically detect that a peer also A DOIC node cannot always automatically detect that a peer also
supports DOIC. For example, a node might have a peer that is a supports DOIC. For example, a node might have a peer that is a
non-supporting agent. If nodes on the other side of that agent non-supporting agent. If nodes on the other side of that agent
send OC-Supported-Features AVPs, the agent is likely to forward send OC-Supported-Features AVPs, the agent is likely to forward
them as unknown AVPs. Messages received across the non-supporting them as unknown AVPs. Messages received across the non-supporting
agent may be indistinguishable from messages received across a agent may be indistinguishable from messages received across a
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adjacent nodes for overload control purposes. Readers should be adjacent nodes for overload control purposes. Readers should be
reminded, however, that the overload control mechanism encourages reminded, however, that the overload control mechanism encourages
Diameter agents to modify AVPs in, or insert additional AVPs into, Diameter agents to modify AVPs in, or insert additional AVPs into,
existing messages that are originated by other nodes. If end-to-end existing messages that are originated by other nodes. If end-to-end
security is enabled, there is a risk that such modification could security is enabled, there is a risk that such modification could
violate integrity protection. The details of using any future violate integrity protection. The details of using any future
Diameter end-to-end security mechanism with overload control will Diameter end-to-end security mechanism with overload control will
require careful consideration, and are beyond the scope of this require careful consideration, and are beyond the scope of this
document. document.
10. Contributors 11. Contributors
The following people contributed substantial ideas, feedback, and The following people contributed substantial ideas, feedback, and
discussion to this document: discussion to this document:
o Eric McMurry o Eric McMurry
o Hannes Tschofenig o Hannes Tschofenig
o Ulrich Wiehe o Ulrich Wiehe
o Jean-Jacques Trottin o Jean-Jacques Trottin
o Maria Cruz Bartolome o Maria Cruz Bartolome
o Martin Dolly o Martin Dolly
o Nirav Salot o Nirav Salot
o Susan Shishufeng o Susan Shishufeng
11. References 12. References
11.1. Normative References 12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
[RFC6733] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn, [RFC6733] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
"Diameter Base Protocol", RFC 6733, October 2012. "Diameter Base Protocol", RFC 6733, October 2012.
11.2. Informative References 12.2. Informative References
[Cx] 3GPP, , "ETSI TS 129 229 V11.4.0", August 2013. [Cx] 3GPP, , "ETSI TS 129 229 V11.4.0", August 2013.
[I-D.ietf-dime-e2e-sec-req] [I-D.ietf-dime-e2e-sec-req]
Tschofenig, H., Korhonen, J., Zorn, G., and K. Pillay, Tschofenig, H., Korhonen, J., Zorn, G., and K. Pillay,
"Diameter AVP Level Security: Scenarios and Requirements", "Diameter AVP Level Security: Scenarios and Requirements",
draft-ietf-dime-e2e-sec-req-00 (work in progress), draft-ietf-dime-e2e-sec-req-01 (work in progress), October
September 2013. 2013.
[PCC] 3GPP, , "ETSI TS 123 203 V11.12.0", December 2013. [PCC] 3GPP, , "ETSI TS 123 203 V11.12.0", December 2013.
[RFC4006] Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J. [RFC4006] Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J.
Loughney, "Diameter Credit-Control Application", RFC 4006, Loughney, "Diameter Credit-Control Application", RFC 4006,
August 2005. August 2005.
[RFC5729] Korhonen, J., Jones, M., Morand, L., and T. Tsou,
"Clarifications on the Routing of Diameter Requests Based
on the Username and the Realm", RFC 5729, December 2009.
[RFC7068] McMurry, E. and B. Campbell, "Diameter Overload Control [RFC7068] McMurry, E. and B. Campbell, "Diameter Overload Control
Requirements", RFC 7068, November 2013. Requirements", RFC 7068, November 2013.
[S13] 3GPP, , "ETSI TS 129 272 V11.9.0", December 2012. [S13] 3GPP, , "ETSI TS 129 272 V11.9.0", December 2012.
Appendix A. Issues left for future specifications Appendix A. Issues left for future specifications
The base solution for the overload control does not cover all The base solution for the overload control does not cover all
possible use cases. A number of solution aspects were intentionally possible use cases. A number of solution aspects were intentionally
left for future specification and protocol work. The following sub- left for future specification and protocol work. The following sub-
sections define some of the potential extensions to the DOIC sections define some of the potential extensions to the DOIC
solution. solution.
A.1. Additional traffic abatement algorithms A.1. Additional traffic abatement algorithms
This specification describes only means for a simple loss based This specification describes only means for a simple loss based
algorithm. Future algorithms can be added using the designed algorithm. Future algorithms can be added using the designed
solution extension mechanism. The new algorithms need to be solution extension mechanism. The new algorithms need to be
registered with IANA. See Sections 6.1 and 8 for the required IANA registered with IANA. See Sections 7.1 and 9 for the required IANA
steps. steps.
A.2. Agent Overload A.2. Agent Overload
This specification focuses on Diameter endpoint (server or client) This specification focuses on Diameter endpoint (server or client)
overload. A separate extension will be required to outline the overload. A separate extension will be required to outline the
handling of the case of agent overload. handling of the case of agent overload.
A.3. New Error Diagnostic AVP A.3. New Error Diagnostic AVP
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