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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (September 24, 2018) is 2034 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) == Unused Reference: 'RFC8379' is defined on line 275, but no explicit reference was found in the text Summary: 0 errors (**), 0 flaws (~~), 3 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: March 28, 2019 W. Henderickx 6 Nokia 7 P. Pillay-Esnault 8 Huawei 9 September 24, 2018 11 OSPF LLS Extensions for Local Interface ID Advertisement 12 draft-ietf-ospf-lls-interface-id-06 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 March 28, 2019. 49 Copyright Notice 51 Copyright (c) 2018 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (https://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 67 1.1. Interface ID Exchange using TE Opaque LSA . . . . . . . . 3 68 2. Interface ID Exchange using OSPF LLS . . . . . . . . . . . . 3 69 2.1. Local Interface Identifier TLV . . . . . . . . . . . . . 4 70 3. Backward Compatibility with RFC 4203 . . . . . . . . . . . . 4 71 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 72 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 73 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 74 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 75 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 76 7.2. Informative References . . . . . . . . . . . . . . . . . 6 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 79 1. Introduction 81 Every OSPF interface is assigned an Interface ID, which uniquely 82 identifies the interface on the router. [RFC2328] uses this 83 Interface ID in the Router-LSA Link Data for unnumbered links and 84 uses the value of the MIB-II IfIndex [RFC2863]. [RFC4203] refers to 85 these Interface IDs as the Link Local/Remote Identifiers and defines 86 a way to advertise and use and use them for Generalized Multi- 87 Protocol Label Switching (GMPLS) purposes. [RFC7684] defines a way 88 to advertise Local/Remote Interface IDs in the OSPFv2 Extended Link 89 LSA. 91 There is a known OSPFv2 protocol problem in verifying the bi- 92 directional connectivity with parallel unnumbered links. If there 93 are two parallel unnumbered links between a pair of routers and each 94 link is only advertised from single direction, such two 95 unidirectional parallel links could be considered as a valid single 96 bidirectional link during the OSPF route computation on some other 97 router. If each link is advertised with both its Local and Remote 98 Interface IDs, the advertisement of each link from both sides of 99 adjacency can be verified by cross-checking the Local and Remote 100 Interface IDs of both advertisements. 102 From the perspective of the advertising router, the Local Interface 103 Identifier is a known value, however the Remote Interface Identifier 104 needs to be learnt before it can be advertised. [RFC4203] suggests 105 to use TE Link Local LSA [RFC3630] to communicate the Local Interface 106 Identifier to neighbors on the link. Though such mechanism works, it 107 has some drawbacks. 109 This draft proposes an extension to OSPF link-local signalling 110 [RFC5613] to advertise the Local Interface Identifier. 112 1.1. Interface ID Exchange using TE Opaque LSA 114 Usage of the Link Local TE Opaque LSA to propagate the Local 115 Interface Identifier to the neighbors on the link is described in 116 [RFC4203]. This mechanism has the following problems: 118 LSAs can only be flooded over an existing adjacency that is in 119 Exchange state or greater. The adjacency state machine progresses 120 independently on each side of the adjacency and, as such, may 121 reach the Full state on one side before the TE Link Opaque LSA 122 arrives. The consequence is that link can be initially advertised 123 without the Remote Interface Identifier. Later, when the TE Link 124 Opaque LSA arrives, the link must be advertised again, this time 125 with the valid Remote Interface Identifier. Implementations may 126 choose to wait before advertising the link, but there is no 127 guarantee that the neighbor will ever advertise the TE Link Opaque 128 LSA with the Interface Identifier. In summary, the existing 129 mechanism does not guarantee that the Remote Interface Identifier 130 is known at the time the link is advertised. 132 The TE Opaque LSA is defined for MPLS Traffic Engineering, but the 133 knowledge of the Remote Interface Identifier is useful also for 134 cases where MPLS TE is not used. One example is the mentioned 135 lack of a valid 2-way connectivity check for parallel point-to- 136 point links between OSPF routers. 138 2. Interface ID Exchange using OSPF LLS 140 To address the problems described earlier and to allow the Interface 141 Identifier exchange to be part of the neighbor discovery process, we 142 propose to extend OSPF link-local signalling to advertise the Local 143 Interface Identifier in OSPF Hello and Database Description (DD) 144 packets. 146 2.1. Local Interface Identifier TLV 148 The Local Interface Identifier TLV is a LLS TLV. It has following 149 format: 151 0 1 2 3 152 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 1 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 154 | Type | Length | 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | Local Interface Identifier | 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 where: 161 Type: 18 163 Length: 4 octets 165 Local Interface Identifier: The value of the local Interface 166 Identifier. 168 Local Interface Identifier TLV signalling using LLS is applicable to 169 all OSPF interface types other than virtual links. 171 3. Backward Compatibility with RFC 4203 173 If the Local Interface ID signaling via Link Local TE Opaque LSA is 174 supported in addition to the new LLS mechanism, implementations which 175 support Local Interface ID signalling using LLS MUST prefer the Local 176 Interface ID value received through LLS over the value received 177 through the Link Local TE Opaque LSA if both are received from the 178 same OSPF router. 180 Implementations which support Local Interface ID signalling via Link 181 Local TE Opaque LSA MAY continue to do so to ensure backward 182 compatibility. If they also support Local Interface ID signalling 183 using LLS as described herein, they MUST signal the same Local 184 Interface ID via both mechanisms. 186 During the rare conditions, when the Local Interface ID changes, a 187 timing interval may exist, where the received values of the Local 188 Interface ID advertised through LLS and Link Local TE Opaque LSA may 189 differ. Such situation is temporary and received values via both 190 mechanisms should become equal as soon as the next Hello and/or Link 191 Local TE Opaque LSA is re-generated by the originator. 193 4. IANA Considerations 195 This specification allocates a single code point from the "Open 196 Shortest Path First (OSPF) Link Local Signalling (LLS) - Type/Length/ 197 Value Identifiers (TLV)" registry. 199 Following value is allocated: 201 o 18 - Local Interface Identifier TLV 203 5. Security Considerations 205 The security considerations for "OSPF Link-Local Signaling" [RFC5613] 206 also apply to the Local Interface Identifier TLV described herein. 207 The current usage of a neighbor's Local Interface Identifier is to 208 disambiguate parallel links between OSPF routers. Hence, 209 modification of the advertised Local Interface Identifier TLV may 210 result in the wrong neighbor interface identifier being advertised in 211 the OSPFv2 Extended Link LSA [RFC7684] and could prevent the link 212 from being used. If authentication is being used in the OSPF routing 213 domain [RFC5709], then the Cryptographic Authentication TLV [RFC5613] 214 SHOULD also be used to protect that contents of the Link-Local 215 Signaling (LLS) block. 217 Receiving a malformed LLS Interface Identifier TLV MUST NOT result in 218 a hard router or OSPF process failure. The reception of malformed 219 LLS TLVs or Sub-TLVs SHOULD be logged but such logging MUST be rate- 220 limited to prevent Denial-of-Service (DoS) attacks. 222 6. Acknowledgements 224 Thanks to Tony Przygienda for his extensive review and useful 225 comments. 227 7. References 229 7.1. Normative References 231 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 232 Requirement Levels", BCP 14, RFC 2119, 233 DOI 10.17487/RFC2119, March 1997, 234 . 236 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 237 DOI 10.17487/RFC2328, April 1998, 238 . 240 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 241 (TE) Extensions to OSPF Version 2", RFC 3630, 242 DOI 10.17487/RFC3630, September 2003, 243 . 245 [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in 246 Support of Generalized Multi-Protocol Label Switching 247 (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, 248 . 250 [RFC5613] Zinin, A., Roy, A., Nguyen, L., Friedman, B., and D. 251 Yeung, "OSPF Link-Local Signaling", RFC 5613, 252 DOI 10.17487/RFC5613, August 2009, 253 . 255 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 256 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 257 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 258 2015, . 260 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 261 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 262 May 2017, . 264 7.2. Informative References 266 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 267 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 268 . 270 [RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M., 271 Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic 272 Authentication", RFC 5709, DOI 10.17487/RFC5709, October 273 2009, . 275 [RFC8379] Hegde, S., Sarkar, P., Gredler, H., Nanduri, M., and L. 276 Jalil, "OSPF Graceful Link Shutdown", RFC 8379, 277 DOI 10.17487/RFC8379, May 2018, 278 . 280 Authors' Addresses 281 Peter Psenak (editor) 282 Cisco Systems, Inc. 283 Apollo Business Center 284 Mlynske nivy 43 285 Bratislava 821 09 286 Slovakia 288 Email: ppsenak@cisco.com 290 Ketan Jivan Talaulikar 291 Cisco Systems, Inc. 292 S.No. 154/6, Phase I, Hinjawadi 293 PUNE, MAHARASHTRA 411 057 294 India 296 Email: ketant@cisco.com 298 Wim Henderickx 299 Nokia 300 Copernicuslaan 50 301 Antwerp 2018 302 BE 304 Email: wim.henderickx@nokia.com 306 Padma Pillay-Esnault 307 Huawei 308 2330 Central Expressway 309 Santa Clara, CA 95050 310 USA 312 Email: padma@huawei.com