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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) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 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: December 21, 2018 W. Henderickx 6 Nokia 7 P. Pillay-Esnault 8 Huawei 9 June 19, 2018 11 OSPF LLS Extensions for Local Interface ID Advertisement 12 draft-ietf-ospf-lls-interface-id-03 14 Abstract 16 This draft describes the extensions to OSPF link-local signaling to 17 advertise the Local Interface Identifier. 19 Requirements Language 21 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 22 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 23 document are to be interpreted as described in RFC 2119 [RFC2119]. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on December 21, 2018. 42 Copyright Notice 44 Copyright (c) 2018 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 60 2. Interface ID Exchange using TE Opaque LSA . . . . . . . . . . 2 61 3. Interface ID Exchange using OSPF LLS . . . . . . . . . . . . 3 62 3.1. Local Interface Identifier TLV . . . . . . . . . . . . . 3 63 4. Backward Compatibility with RFC 4203 . . . . . . . . . . . . 4 64 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 65 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 66 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 4 67 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 68 9. Normative References . . . . . . . . . . . . . . . . . . . . 5 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 71 1. Introduction 73 Every interface is assigned an Interface ID, which uniquely 74 identifies the interface on the router. For example, some 75 implementations MAY be able to use the MIB-II IfIndex [RFC2863] as 76 the Interface ID. 78 Local/Remote Interface Identifiers MAY be flooded by OSPF [RFC2328] 79 as defined in [RFC4203]. From the perspective of the advertising 80 router, the Local Interface Identifier is a known value, however the 81 Remote Interface Identifier needs to be learnt before it can be 82 advertised. [RFC4203] suggests to use TE Link Local LSA [RFC3630] to 83 communicate the Local Interface Identifier to neighbors on the link. 84 Though such mechanism works, it has some drawbacks. 86 This draft proposes an extension to OSPF link-local signaling (LLS) 87 [RFC5613] to advertise the Local Interface Identifier. 89 2. Interface ID Exchange using TE Opaque LSA 91 Usage of the Link Local TE Opaque LSA to propagate the Local 92 Interface Identifier to the neighbors on the link is described in 93 [RFC4203]. This mechanism has following problems: 95 LSAs can only be flooded over an existing adjacency that is in 96 Exchange state or greater. The adjacency state machine progresses 97 independently on each side of the adjacency and, as such, may 98 reach the Full state on one side before the TE Link Opaque LSA 99 arrives. The consequence is that link can be initially advertised 100 without the Remote Interface Identifier. Later, when the TE Link 101 Opaque LSA arrives, the link must be advertised again, this time 102 with the valid Remote Interface Identifier. Implementations may 103 choose to wait before advertising the link, but there is no 104 guarantee that the neighbor will ever advertise the TE Link Opaque 105 LSA with the Interface Identifier. In summary, the existing 106 mechanism does not guarantee that the Remote Interface Identifier 107 is known at the time the link is advertised. 109 The TE Opaque LSA is defined for MPLS Traffic Engineering, but the 110 knowledge of the Remote Interface Identifier is useful for other 111 cases where MPLS TE is not used. One example is the lack of a 112 valid 2-way connectivity check for parallel point-to-point links 113 between OSPF routers. In such cases, TE Opaque LSAs are not 114 exchanged solely for 2-way connectivity validation. 116 3. Interface ID Exchange using OSPF LLS 118 To address the problems described earlier and to allow the Interface 119 Identifier exchange to be part of the neighbor discovery process, we 120 propose to extend OSPF link-local signaling to advertise the Local 121 Interface Identifier in OSPF Hello packets. 123 3.1. Local Interface Identifier TLV 125 The Local Interface Identifier TLV is a LLS TLV. It has following 126 format: 128 0 1 2 3 129 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 1 130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 | Type | Length | 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | Local Interface Identifier | 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 where: 138 Type: TBD, suggested value 18 140 Length: 4 octet 142 Local Interface Identifier: The value of the local Interface 143 Identifier. 145 Local Interface Identifier TLV signalling using LLS is applicable to 146 all OSPF interface types other than virtual links. 148 4. Backward Compatibility with RFC 4203 150 Implementations which support Local Interface ID signalling using LLS 151 MUST prefer the Local Interface ID value received through LLS over 152 the value received through Link Local TE Opaque LSA if both are 153 received from the same OSPF router. 155 Implementations which support Local Interface ID signalling via Link 156 Local TE Opaque LSA MAY continue to do so to ensure backward 157 compatibility. If they also support Local Interface ID signalling 158 using LLS as described herein, they SHOULD signal the same Local 159 Interface ID via both mechanisms. 161 During the rare conditions, when the Local Interface ID changes, a 162 timing interval may exist, where the received values of the Local 163 Interface ID advertised through LLS and Link Local TE Opaque LSA may 164 differ. Such situation is temporary and received values via both 165 mechanisms should become equal as soon as the next Hello and/or Link 166 Local TE Opaque LSA is re-generated by the originator. 168 5. IANA Considerations 170 This specification updates Link Local Signalling TLV Identifiers 171 registry. 173 Following values is allocated: 175 o 18 - Local Interface Identifier TLV 177 6. Security Considerations 179 Implementations must assure that malformed LLS TLVs and Sub-TLVs 180 permutations do not result in errors which cause hard OSPF failures. 182 7. Contributors 184 8. Acknowledgements 186 Thanks to Tony Przygienda for his extensive review and useful 187 comments. 189 9. Normative References 191 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 192 Requirement Levels", BCP 14, RFC 2119, 193 DOI 10.17487/RFC2119, March 1997, 194 . 196 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 197 DOI 10.17487/RFC2328, April 1998, 198 . 200 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 201 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 202 . 204 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 205 (TE) Extensions to OSPF Version 2", RFC 3630, 206 DOI 10.17487/RFC3630, September 2003, 207 . 209 [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in 210 Support of Generalized Multi-Protocol Label Switching 211 (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, 212 . 214 [RFC5613] Zinin, A., Roy, A., Nguyen, L., Friedman, B., and D. 215 Yeung, "OSPF Link-Local Signaling", RFC 5613, 216 DOI 10.17487/RFC5613, August 2009, 217 . 219 Authors' Addresses 221 Peter Psenak (editor) 222 Cisco Systems, Inc. 223 Apollo Business Center 224 Mlynske nivy 43 225 Bratislava 821 09 226 Slovakia 228 Email: ppsenak@cisco.com 229 Ketan Jivan Talaulikar 230 Cisco Systems, Inc. 231 S.No. 154/6, Phase I, Hinjawadi 232 PUNE, MAHARASHTRA 411 057 233 India 235 Email: ketant@cisco.com 237 Wim Henderickx 238 Nokia 239 Copernicuslaan 50 240 Antwerp 2018 241 BE 243 Email: wim.henderickx@nokia.com 245 Padma Pillay-Esnault 246 Huawei 247 2330 Central Expressway 248 Santa Clara, CA 95050 249 USA 251 Email: padma@huawei.com