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Pillay-Esnault 8 Huawei 9 May 24, 2017 11 OSPF LLS Extensions for Local Interface ID Advertisement 12 draft-ietf-ospf-lls-interface-id-00 14 Abstract 16 This draft describes the extensions to OSPF link-local signaling to 17 advertise 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 http://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 November 25, 2017. 42 Copyright Notice 44 Copyright (c) 2017 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 (http://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 . . . . . . . . . . . . . . . . . . . . 4 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 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. Implementation 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 Remote Interface Identifier is 107 known at the time the link is advertised. 109 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 valid 112 2-way connectivity check for remote parallel point-to-point links 113 in OSPF. In such case, TE Opaque LSAs are not exchanged solely 114 for 2-way connectivity correctness. 116 3. Interface ID Exchange using OSPF LLS 118 To address the problems described earlier and to allow the Interface 119 Identifiers 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 new LLS TLV. It has 126 following 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 MUST be present in all Hello packets 146 on all link types, except packets that are sent to the remote end of 147 the virtual-link. 149 4. Backward Compatibility with RFC 4203 151 Implementations which support Local Interface ID signalling using LLS 152 MUST prefer the Local Interface ID value received through LLS over 153 the value received through the Link Local TE Opaque LSAs. 155 Implementations which also support the Local Interface ID signalling 156 via Link Local TE Opaque LSA MAY continue to do so to ensure backward 157 compatibility and they MUST signal the same local interface id via 158 both mechanisms. 160 During the rare conditions, when the Local Interface ID changes, a 161 timing interval may exist, where the received values of the Local 162 Interface ID advertised through LLS and Link Local TE Opaque LSA may 163 differ. Such situation is temporary and received values via both 164 mechanisms should become equal as soon as the next Hello and/or Link 165 Local TE Opaque LSA is re-generated by the originator. 167 5. IANA Considerations 169 This specification updates Link Local Signalling TLV Identifiers 170 registry. 172 Following values is allocated: 174 o 18 - Local Interface Identifier TLV 176 6. Security Considerations 178 Implementations must assure that malformed LLS TLV and Sub-TLV 179 permutations do not result in errors which cause hard OSPF failures. 181 7. Contributors 183 8. Acknowledgements 185 Thanks to Tony Przygienda for his extensive review and useful 186 comments. 188 9. Normative References 190 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 191 Requirement Levels", BCP 14, RFC 2119, 192 DOI 10.17487/RFC2119, March 1997, 193 . 195 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 196 DOI 10.17487/RFC2328, April 1998, 197 . 199 [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group 200 MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, 201 . 203 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 204 (TE) Extensions to OSPF Version 2", RFC 3630, 205 DOI 10.17487/RFC3630, September 2003, 206 . 208 [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in 209 Support of Generalized Multi-Protocol Label Switching 210 (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, 211 . 213 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 214 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 215 . 217 [RFC5613] Zinin, A., Roy, A., Nguyen, L., Friedman, B., and D. 218 Yeung, "OSPF Link-Local Signaling", RFC 5613, 219 DOI 10.17487/RFC5613, August 2009, 220 . 222 Authors' Addresses 224 Peter Psenak (editor) 225 Cisco Systems, Inc. 226 Apollo Business Center 227 Mlynske nivy 43 228 Bratislava 821 09 229 Slovakia 231 Email: ppsenak@cisco.com 232 Ketan Jivan Talaulikar 233 Cisco Systems, Inc. 234 S.No. 154/6, Phase I, Hinjawadi 235 PUNE, MAHARASHTRA 411 057 236 India 238 Email: ketant@cisco.com 240 Wim Henderickx 241 Nokia 242 Copernicuslaan 50 243 Antwerp 2018 244 BE 246 Email: wim.henderickx@nokia.com 248 Padma Pillay-Esnault 249 Huawei 250 2330 Central Expressway 251 Santa Clara, CA 95050 252 USA 254 Email: padma@huawei.com