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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (October 10, 2018) is 2022 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Open Shortest Path First IGP P. Psenak, Ed. 3 Internet-Draft K. Talaulikar 4 Intended status: Standards Track Cisco Systems, Inc. 5 Expires: April 13, 2019 W. Henderickx 6 Nokia 7 P. Pillay-Esnault 8 Huawei 9 October 10, 2018 11 OSPF LLS Extensions for Local Interface ID Advertisement 12 draft-ietf-ospf-lls-interface-id-07 14 Abstract 16 Every OSPF interface is assigned an identifier, Interface ID, which 17 uniquely identifies the interface on the router. In some cases it is 18 useful to know the assigned Interface ID on the remote side of the 19 adjacency (Remote Interface ID). 21 This draft describes the extensions to OSPF link-local signalling to 22 advertise the Local Interface Identifier. 24 Requirements Language 26 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 27 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 28 "OPTIONAL" in this document are to be interpreted as described in 29 BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all 30 capitals, as shown here. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at https://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on April 13, 2019. 49 Internet-DrafOSPF Link Local Signalling (LLS) Extensions fo October 2018 51 Copyright Notice 53 Copyright (c) 2018 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (https://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 69 1.1. Interface ID Exchange using TE Opaque LSA . . . . . . . . 3 70 2. Interface ID Exchange using OSPF LLS . . . . . . . . . . . . 3 71 2.1. Local Interface Identifier TLV . . . . . . . . . . . . . 4 72 3. Backward Compatibility with RFC 4203 . . . . . . . . . . . . 4 73 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 74 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 75 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 76 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 77 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 78 7.2. Informative References . . . . . . . . . . . . . . . . . 6 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 81 1. Introduction 83 Every OSPF interface is assigned an Interface ID, which uniquely 84 identifies the interface on the router. [RFC2328] uses this 85 Interface ID in the Router-LSA Link Data for unnumbered links and 86 uses the value of the MIB-II IfIndex [RFC2863]. [RFC4203] refers to 87 these Interface IDs as the Link Local/Remote Identifiers and defines 88 a way to advertise and use and use them for Generalized Multi- 89 Protocol Label Switching (GMPLS) purposes. [RFC7684] defines a way 90 to advertise Local/Remote Interface IDs in the OSPFv2 Extended Link 91 LSA. 93 There is a known OSPFv2 protocol problem in verifying the bi- 94 directional connectivity with parallel unnumbered links. If there 95 are two parallel unnumbered links between a pair of routers and each 96 link is only advertised from single direction, such two 97 unidirectional parallel links could be considered as a valid single 98 bidirectional link during the OSPF route computation on some other 100 Internet-DrafOSPF Link Local Signalling (LLS) Extensions fo October 2018 102 router. If each link is advertised with both its Local and Remote 103 Interface IDs, the advertisement of each link from both sides of 104 adjacency can be verified by cross-checking the Local and Remote 105 Interface IDs of both advertisements. 107 From the perspective of the advertising router, the Local Interface 108 Identifier is a known value, however the Remote Interface Identifier 109 needs to be learnt before it can be advertised. [RFC4203] suggests 110 to use TE Link Local LSA [RFC3630] to communicate the Local Interface 111 Identifier to neighbors on the link. Though such mechanism works, it 112 has some drawbacks. 114 This draft proposes an extension to OSPF link-local signalling 115 [RFC5613] to advertise the Local Interface Identifier. 117 1.1. Interface ID Exchange using TE Opaque LSA 119 Usage of the Link Local TE Opaque LSA to propagate the Local 120 Interface Identifier to the neighbors on the link is described in 121 [RFC4203]. This mechanism has the following problems: 123 LSAs can only be flooded over an existing adjacency that is in 124 Exchange state or greater. The adjacency state machine progresses 125 independently on each side of the adjacency and, as such, may 126 reach the Full state on one side before the TE Link Opaque LSA 127 arrives. The consequence is that link can be initially advertised 128 without the Remote Interface Identifier. Later, when the TE Link 129 Opaque LSA arrives, the link must be advertised again, this time 130 with the valid Remote Interface Identifier. Implementations may 131 choose to wait before advertising the link, but there is no 132 guarantee that the neighbor will ever advertise the TE Link Opaque 133 LSA with the Interface Identifier. In summary, the existing 134 mechanism does not guarantee that the Remote Interface Identifier 135 is known at the time the link is advertised. 137 The TE Opaque LSA is defined for MPLS Traffic Engineering, but the 138 knowledge of the Remote Interface Identifier is useful also for 139 cases where MPLS TE is not used. One example is the mentioned 140 lack of a valid 2-way connectivity check for parallel point-to- 141 point links between OSPF routers. 143 2. Interface ID Exchange using OSPF LLS 145 To address the problems described earlier and to allow the Interface 146 Identifier exchange to be part of the neighbor discovery process, we 147 propose to extend OSPF link-local signalling to advertise the Local 148 Interface Identifier in OSPF Hello and Database Description (DD) 149 packets. 151 Internet-DrafOSPF Link Local Signalling (LLS) Extensions fo October 2018 153 2.1. Local Interface Identifier TLV 155 The Local Interface Identifier TLV is a LLS TLV. It has following 156 format: 158 0 1 2 3 159 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 | Type | Length | 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 | Local Interface Identifier | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 where: 168 Type: TBD 170 Length: 4 octets 172 Local Interface Identifier: The value of the local Interface 173 Identifier. 175 Local Interface Identifier TLV signalling using LLS is applicable to 176 all OSPF interface types other than virtual links. 178 3. Backward Compatibility with RFC 4203 180 If the Local Interface ID signaling via Link Local TE Opaque LSA is 181 supported in addition to the new LLS mechanism, implementations which 182 support Local Interface ID signalling using LLS MUST prefer the Local 183 Interface ID value received through LLS over the value received 184 through the Link Local TE Opaque LSA if both are received from the 185 same OSPF router. 187 Implementations which support Local Interface ID signalling via Link 188 Local TE Opaque LSA MAY continue to do so to ensure backward 189 compatibility. If they also support Local Interface ID signalling 190 using LLS as described herein, they MUST signal the same Local 191 Interface ID via both mechanisms. 193 During the rare conditions, when the Local Interface ID changes, a 194 timing interval may exist, where the received values of the Local 195 Interface ID advertised through LLS and Link Local TE Opaque LSA may 196 differ. Such situation is temporary and received values via both 197 mechanisms should become equal as soon as the next Hello and/or Link 198 Local TE Opaque LSA is re-generated by the originator. 200 Internet-DrafOSPF Link Local Signalling (LLS) Extensions fo October 2018 202 4. IANA Considerations 204 This specification allocates a single code point from the "Open 205 Shortest Path First (OSPF) Link Local Signalling (LLS) - Type/Length/ 206 Value Identifiers (TLV)" registry. 208 Following value is allocated: 210 o TBD - Local Interface Identifier TLV 212 5. Security Considerations 214 The security considerations for "OSPF Link-Local Signaling" [RFC5613] 215 also apply to the Local Interface Identifier TLV described herein. 216 The current usage of a neighbor's Local Interface Identifier is to 217 disambiguate parallel links between OSPF routers. Hence, 218 modification of the advertised Local Interface Identifier TLV may 219 result in the wrong neighbor interface identifier being advertised in 220 the OSPFv2 Extended Link LSA [RFC7684] and could prevent the link 221 from being used. If authentication is being used in the OSPF routing 222 domain [RFC5709], then the Cryptographic Authentication TLV [RFC5613] 223 SHOULD also be used to protect that contents of the Link-Local 224 Signaling (LLS) block. 226 Receiving a malformed LLS Interface Identifier TLV MUST NOT result in 227 a hard router or OSPF process failure. The reception of malformed 228 LLS TLVs or Sub-TLVs SHOULD be logged but such logging MUST be rate- 229 limited to prevent Denial-of-Service (DoS) attacks. 231 6. Acknowledgements 233 Thanks to Tony Przygienda for his extensive review and useful 234 comments. 236 7. References 238 7.1. Normative References 240 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 241 Requirement Levels", BCP 14, RFC 2119, 242 DOI 10.17487/RFC2119, March 1997, 243 . 245 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 246 DOI 10.17487/RFC2328, April 1998, 247 . 249 Internet-DrafOSPF Link Local Signalling (LLS) Extensions fo October 2018 251 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 252 (TE) Extensions to OSPF Version 2", RFC 3630, 253 DOI 10.17487/RFC3630, September 2003, 254 . 256 [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in 257 Support of Generalized Multi-Protocol Label Switching 258 (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, 259 . 261 [RFC5613] Zinin, A., Roy, A., Nguyen, L., Friedman, B., and D. 262 Yeung, "OSPF Link-Local Signaling", RFC 5613, 263 DOI 10.17487/RFC5613, August 2009, 264 . 266 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 267 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 268 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 269 2015, . 271 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 272 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 273 May 2017, . 275 7.2. Informative References 277 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 278 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 279 . 281 [RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M., 282 Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic 283 Authentication", RFC 5709, DOI 10.17487/RFC5709, October 284 2009, . 286 Authors' Addresses 288 Peter Psenak (editor) 289 Cisco Systems, Inc. 290 Apollo Business Center 291 Mlynske nivy 43 292 Bratislava 821 09 293 Slovakia 295 Email: ppsenak@cisco.com 297 Internet-DrafOSPF Link Local Signalling (LLS) Extensions fo October 2018 299 Ketan Jivan Talaulikar 300 Cisco Systems, Inc. 301 S.No. 154/6, Phase I, Hinjawadi 302 PUNE, MAHARASHTRA 411 057 303 India 305 Email: ketant@cisco.com 307 Wim Henderickx 308 Nokia 309 Copernicuslaan 50 310 Antwerp 2018 311 BE 313 Email: wim.henderickx@nokia.com 315 Padma Pillay-Esnault 316 Huawei 317 2330 Central Expressway 318 Santa Clara, CA 95050 319 USA 321 Email: padma@huawei.com