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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) == Outdated reference: A later version (-25) exists of draft-ietf-isis-segment-routing-extensions-04 Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Networking Working Group L. Ginsberg 3 Internet-Draft Cisco Systems 4 Intended status: Standards Track B. Decraene 5 Expires: December 22, 2015 Orange 6 C. Filsfils 7 Cisco Systems 8 S. Litkowski 9 Orange Business Service 10 S. Previdi 11 Cisco Systems 12 X. Xu 13 Huawei 14 U. Chunduri 15 Ericsson 16 June 20, 2015 18 IS-IS Prefix Attributes for Extended IP and IPv6 Reachability 19 draft-ietf-isis-prefix-attributes-01.txt 21 Abstract 23 This document introduces new sub-TLVs to support advertisement of 24 prefix attribute flags and the source router ID of the router which 25 originated a prefix advertisement. 27 Requirements Language 29 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 30 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 31 document are to be interpreted as described in RFC 2119 [RFC2119]. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at http://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on December 22, 2015. 50 Copyright Notice 52 Copyright (c) 2015 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 This document may contain material from IETF Documents or IETF 66 Contributions published or made publicly available before November 67 10, 2008. The person(s) controlling the copyright in some of this 68 material may not have granted the IETF Trust the right to allow 69 modifications of such material outside the IETF Standards Process. 70 Without obtaining an adequate license from the person(s) controlling 71 the copyright in such materials, this document may not be modified 72 outside the IETF Standards Process, and derivative works of it may 73 not be created outside the IETF Standards Process, except to format 74 it for publication as an RFC or to translate it into languages other 75 than English. 77 Table of Contents 79 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 80 2. New sub-TLVs for Extended Reachability TLVs . . . . . . . . . 3 81 2.1. IPv4/IPv6 Extended Reachability Attribute Flags . . . . . 3 82 2.2. IPv4/IPv6 Source Router ID . . . . . . . . . . . . . . . 5 83 2.3. Advertising Router IDs . . . . . . . . . . . . . . . . . 5 84 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 85 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 86 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 87 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 88 6.1. Normative References . . . . . . . . . . . . . . . . . . 6 89 6.2. Informational References . . . . . . . . . . . . . . . . 7 90 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 92 1. Introduction 94 There are existing use cases in which knowing additional attributes 95 of a prefix is useful. For example, it is useful to know whether an 96 advertised prefix is directly connected to the advertising router or 97 not. In the case of [SR] knowing whether a prefix is directly 98 connected or not determines what action should be taken as regards 99 processing of labels associated with an incoming packet. Current 100 formats of the Extended Reachability TLVs for both IP and IPv6 are 101 fixed and do not allow the introduction of additional flags without 102 backwards compatibility issues. Therefore a new sub-TLV is 103 introduced which allows for the advertisement of attribute flags 104 associated with prefix advertisements. 106 It is also useful to know the source of a prefix advertisement when 107 the advertisement has been leaked to another level. Therefore a new 108 sub-TLV is introduced to advertise the router-id of the originator of 109 a prefix advertisement. 111 2. New sub-TLVs for Extended Reachability TLVs 113 The following new sub-TLVs are introduced: 115 o IPv4/IPv6 Extended Reachability Attributes 117 o IPv4 Source Router ID 119 o IPv6 Source Router ID 121 All sub-TLVs are applicable to TLVs 135, 235, 236, and/or 237. 123 2.1. IPv4/IPv6 Extended Reachability Attribute Flags 125 This sub-TLV supports the advertisement of additional flags 126 associated with a given prefix advertisement. The behavior of each 127 flag when a prefix advertisement is leaked from one level to another 128 (upwards or downwards) is explicitly defined below. 130 All flags are applicable to TLVs 135, 235, 236, 237 unless otherwise 131 stated. 133 Prefix Attribute Flags 134 Type: 4 (suggested - to be assigned by IANA) 135 Length: Number of octets to follow 136 Value 138 (Length * 8) bits. 140 0 1 2 3 4 5 6 7... 141 +-+-+-+-+-+-+-+-+... 142 |X|R|N| ... 143 +-+-+-+-+-+-+-+-+... 145 Bits are defined/sent starting with Bit #0 defined below. Additional 146 bit definitions which may be defined in the future SHOULD be assigned 147 in ascending bit order so as to minimize the number of bits which 148 will need to be transmitted. 150 Undefined bits SHOULD be transmitted as 0 and MUST be 151 ignored on receipt. 153 Bits which are NOT transmitted MUST be treated as if they are 154 set to 0 on receipt. 156 X-Flag: External Prefix Flag (Bit 0) 157 Set if the prefix has been redistributed from another protocol. 158 This includes the case where multiple virtual routers are 159 supported and the source of the redistributed prefix is another 160 IS-IS instance. 161 The flag MUST be preserved when leaked between levels. 162 In TLVs 236 and 237 this flag SHOULD always be sent as 0 and 163 MUST be ignored on receipt. This is because there is an existing 164 X flag defined in the fixed format of these TLVs as specified in 165 [RFC5308] and [RFC5120]. 167 R-Flag: Re-advertisement Flag (Bit 1) 168 Set when the prefix has been leaked from one level to another 169 (upwards or downwards). 171 N-flag: Node Flag (Bit 2) 172 Set when the prefix identifies the advertising router i.e., the 173 prefix is a host prefix advertising a globally reachable address 174 typically associated with a loopback address. 175 The advertising router MAY choose to NOT set this flag even when 176 the above conditions are met. 177 If the flag is set and the prefix length is NOT a host prefix 178 (/32 for IPV4, /128 for IPv6) then the flag MUST be ignored. 179 The flag MUST be preserved when leaked between levels. 181 2.2. IPv4/IPv6 Source Router ID 183 When a reachability advertisement is leaked from one level to 184 another, the source of the original advertisement is unknown. In 185 cases where the advertisement is an identifier for the advertising 186 router (e.g., N-flag set in the Extended Reachability Attribute sub- 187 TLV as described in the previous section) it may be useful for other 188 routers to know the source of the advertisement. The sub-TLVs 189 defined below provide this information. 191 IPv4 Source Router ID 192 Type: 11 (suggested - to be assigned by IANA) 193 Length: 4 194 Value: IPv4 Router ID of the source of the advertisement 196 Inclusion of this TLV is optional and MAY occur in TLVs 197 135, 235, 236, or 237. When included the value MUST be 198 identical to the value advertised in Traffic Engineering 199 router ID (TLV 134) defined in [RFC5305]. 201 If present the sub-TLV MUST be included when the prefix 202 advertisement is leaked to another level. 204 IPv6 Source Router ID 205 Type: 12 (suggested - to be assigned by IANA) 206 Length: 16 207 Value: IPv6 Router ID of the source of the advertisement 209 Inclusion of this TLV is optional and MAY occur in TLVs 210 135, 235, 236, or 237. When included the value MUST be 211 identical to the value advertised in IPv6 TE Router ID 212 (TLV 140) defined in [RFC6119]. 214 If present the sub-TLV MUST be included when the prefix 215 advertisement is leaked to another level. 217 2.3. Advertising Router IDs 219 [RFC5305] and [RFC6119] define the advertisement of router IDs for 220 IPv4 and IPv6 respectively. Although both drafts discuss the use of 221 router ID in the context of Traffic Engineering (TE), the 222 advertisement of router IDs is explicitly allowed for purposes other 223 than TE. The use of router IDs to identify the source of a prefix 224 advertisement as defined in the previous section is one such use 225 case. Therefore, whenever the source router ID sub-TLVs defined in 226 the previous section are used, the originating router SHOULD also 227 advertise the corresponding address-family specific router ID TLV(s). 229 3. IANA Considerations 231 This document adds the following new sub-TLVs to the registry of sub- 232 TLVs for TLVs 135, 235, 236, 237. 234 Value: 4 (suggested - to be assigned by IANA) 236 Name: Prefix Attribute Flags 238 Value: 11 (suggested - to be assigned by IANA) 240 Name: IPv4 Source Router ID 242 Value: 12 (suggested - to be assigned by IANA) 244 Name: IPv6 Source Router ID 246 This document also introduces a new registry for bit values in the 247 Prefix Attribute Flags sub-TLV. Registration policy is Expert Review 248 as defined in [RFC5226]. Defined values are: 250 Bit # Name 251 ----- ------------------------ 252 0 External Prefix Flag 253 1 Re-advertisement Flag 254 2 Node Flag 256 4. Security Considerations 258 None. 260 5. Acknowledgements 262 TBD 264 6. References 266 6.1. Normative References 268 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 269 Requirement Levels", BCP 14, RFC 2119, March 1997. 271 [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi 272 Topology (MT) Routing in Intermediate System to 273 Intermediate Systems (IS-ISs)", RFC 5120, February 2008. 275 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 276 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 277 May 2008. 279 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 280 Engineering", RFC 5305, October 2008. 282 [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, October 283 2008. 285 [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic 286 Engineering in IS-IS", RFC 6119, February 2011. 288 6.2. Informational References 290 [SR] "IS-IS Extensions for Segment Routing, draft-ietf-isis- 291 segment-routing-extensions-04(work in progress)", May 292 2015. 294 Authors' Addresses 296 Les Ginsberg 297 Cisco Systems 298 510 McCarthy Blvd. 299 Milpitas, CA 95035 300 USA 302 Email: ginsberg@cisco.com 304 Bruno Decraene 305 Orange 306 38 rue du General Leclerc 307 MIssy Moulineaux cedex 9 92794 308 France 310 Email: bruno.decraene@orange.com 312 Clarence Filsfils 313 Cisco Systems 315 Email: cf@cisco.com 316 Stephane Litkowski 317 Orange Business Service 319 Email: stephane.litkowski@orange.com 321 Stefano Previdi 322 Cisco Systems 323 Via Del Serafico 200 324 Rome 0144 325 Italy 327 Email: sprevidi@cisco.com 329 Xiaohu Xu 330 Huawei 332 Email: xuxiaohu@huawei.com 334 Uma Chunduri 335 Ericsson 337 Email: uma.chunduri@ericsson.com