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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) == Outdated reference: draft-ietf-isis-segment-routing-extensions has been published as RFC 8667 Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 1 comment (--).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: November 11, 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 May 10, 2015 18 IS-IS Prefix Attributes for Extended IP and IPv6 Reachability 19 draft-ietf-isis-prefix-attributes-00.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 November 11, 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 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 84 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 85 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 86 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 87 6.1. Normative References . . . . . . . . . . . . . . . . . . 6 88 6.2. Informational References . . . . . . . . . . . . . . . . 6 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 91 1. Introduction 93 There are existing use cases in which knowing additional attributes 94 of a prefix is useful. For example, it is useful to know whether an 95 advertised prefix is directly connected to the advertising router or 96 not. In the case of [SR] knowing whether a prefix is directly 97 connected or not determines what action should be taken as regards 98 processing of labels associated with an incoming packet. Current 99 formats of the Extended Reachability TLVs for both IP and IPv6 are 100 fixed and do not allow the introduction of additional flags without 101 backwards compatibility issues. Therefore a new sub-TLV is 102 introduced which allows for the advertisement of attribute flags 103 associated with prefix advertisements. 105 It is also useful to know the source of a prefix advertisement when 106 the advertisement has been leaked to another level. Therefore a new 107 sub-TLV is introduced to advertise the router-id of the originator of 108 a prefix advertisement. 110 2. New sub-TLVs for Extended Reachability TLVs 112 The following new sub-TLVs are introduced: 114 o IPv4/IPv6 Extended Reachability Attributes 116 o IPv4 Source Router ID 118 o IPv6 Source Router ID 120 All sub-TLVs are applicable to TLVs 135, 235, 236, and/or 237. 122 2.1. IPv4/IPv6 Extended Reachability Attribute Flags 124 This sub-TLV supports the advertisement of additional flags 125 associated with a given prefix advertisement. The behavior of each 126 flag when a prefix advertisement is leaked from one level to another 127 (upwards or downwards) is explicitly defined below. 129 All flags are applicable to TLVs 135, 235, 236, 237 unless otherwise 130 stated. 132 Prefix Attribute Flags 133 Type: 4 (suggested - to be assigned by IANA) 134 Length: Number of octets to follow 135 Value 137 (Length * 8) bits. 139 0 1 2 3 4 5 6 7... 140 +-+-+-+-+-+-+-+-+... 141 |X|R|N| ... 142 +-+-+-+-+-+-+-+-+... 144 Bits are defined/sent starting with Bit #0 defined below. Additional 145 bit definitions which may be defined in the future SHOULD be assigned 146 in ascending bit order so as to minimize the number of bits which 147 will need to be transmitted. 149 Undefined bits SHOULD be transmitted as 0 and MUST be 150 ignored on receipt. 152 Bits which are NOT transmitted MUST be treated as if they are 153 set to 0 on receipt. 155 X-Flag: External Prefix Flag (Bit 0) 156 Set if the prefix has been redistributed from another protocol. 157 This includes the case where multiple virtual routers are 158 supported and the source of the redistributed prefix is another 159 IS-IS instance. 160 The flag is preserved when leaked between levels. 161 In TLVs 236 and 237 this flag SHOULD always be sent as 0 and 162 MUST be ignored on receipt. This is because there is an existing 163 X flag defined in the fixed format of these TLVs as specified in 164 [RFC5308] and [RFC5120]. 166 R-Flag: Re-advertisement Flag (Bit 1) 167 Set when the prefix has been leaked from one level to another 168 (upwards or downwards). 170 N-flag: Node Flag (Bit 2) 171 Set when the prefix identifies the advertising router i.e., the 172 prefix is a host prefix advertising a globally reachable address 173 typically associated with a loopback address. 174 The advertising router MAY choose to NOT set this flag even when 175 the above conditions are met. 176 If the flag is set and the prefix length is NOT a host prefix 177 (/32 for IPV4, /128 for IPv6) then the flag MUST be ignored. 178 The flag is preserved when leaked between levels. 180 2.2. IPv4/IPv6 Source Router ID 182 When a reachability advertisement is leaked from one level to 183 another, the source of the original advertisement is unknown. In 184 cases where the advertisement is an identifier for the advertising 185 router (e.g., N-flag set in the Extended Reachability Attribute sub- 186 TLV as described in the previous section) it may be useful for other 187 routers to know the source of the advertisement. The sub-TLVs 188 defined below provide this information. 190 IPv4 Source Router ID 191 Type: 11 (suggested - to be assigned by IANA) 192 Length: 4 193 Value: IPv4 Router ID of the source of the advertisement 195 Inclusion of this TLV is optional and MAY occur in TLVs 196 135, 235, 236, or 237. 198 If present the sub-TLV MUST be included when the prefix 199 advertisement is leaked to another level. 201 IPv6 Source Router ID 202 Type: 12 (suggested - to be assigned by IANA) 203 Length: 16 204 Value: IPv6 Router ID of the source of the advertisement 206 Inclusion of this TLV is optional and MAY occur in TLVs 207 135, 235, 236, or 237. 209 If present the sub-TLV MUST be included when the prefix 210 advertisement is leaked to another level. 212 3. IANA Considerations 214 This document adds the following new sub-TLVs to the registry of sub- 215 TLVs for TLVs 135, 235, 236, 237. 217 Value: 4 (suggested - to be assigned by IANA) 219 Name: Prefix Attribute Flags 221 Value: 11 (suggested - to be assigned by IANA) 223 Name: IPv4 Source Router ID 225 Value: 12 (suggested - to be assigned by IANA) 226 Name: IPv6 Source Router ID 228 This document also introduces a new registry for bit values in the 229 Prefix Attribute Flags sub-TLV. Registration policy is Expert Review 230 as defined in [RFC5226]. Defined values are: 232 Bit # Name 233 ----- ------------------------ 234 0 External Prefix Flag 235 1 Re-advertisement Flag 236 2 Node Flag 238 4. Security Considerations 240 None. 242 5. Acknowledgements 244 TBD 246 6. References 248 6.1. Normative References 250 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 251 Requirement Levels", BCP 14, RFC 2119, March 1997. 253 [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi 254 Topology (MT) Routing in Intermediate System to 255 Intermediate Systems (IS-ISs)", RFC 5120, February 2008. 257 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 258 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 259 May 2008. 261 [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, October 262 2008. 264 6.2. Informational References 266 [SR] "IS-IS Extensions for Segment Routing, draft-ietf-isis- 267 segment-routing-extensions-04(work in progress)", May 268 2015. 270 Authors' Addresses 272 Les Ginsberg 273 Cisco Systems 274 510 McCarthy Blvd. 275 Milpitas, CA 95035 276 USA 278 Email: ginsberg@cisco.com 280 Bruno Decraene 281 Orange 282 38 rue du General Leclerc 283 MIssy Moulineaux cedex 9 92794 284 France 286 Email: bruno.decraene@orange.com 288 Clarence Filsfils 289 Cisco Systems 291 Email: cfilsfil@cisco.com 293 Stephane Litkowski 294 Orange Business Service 296 Email: stephane.litkowski@orange.com 298 Stefano Previdi 299 Cisco Systems 300 Via Del Serafico 200 301 Rome 0144 302 Italy 304 Email: sprevidi@cisco.com 306 Xiaohu Xu 307 Huawei 309 Email: xuxiaohu@huawei.com 310 Uma Chunduri 311 Ericsson 313 Email: uma.chunduri@ericsson.com