Open Shortest Path First IGP P. Psenak, Ed. Internet-Draft K. Talaulikar Intended status: Standards Track Cisco Systems, Inc. Expires: November 25, 2017 W. Henderickx Nokia P. Pillay-Esnault Huawei May 24, 2017 OSPF LLS Extensions for Local Interface ID Advertisement draft-ietf-ospf-lls-interface-id-00 Abstract This draft describes the extensions to OSPF link-local signaling to advertise Local Interface Identifier. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on November 25, 2017. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents Psenak, et al. Expires November 25, 2017 [Page 1] Internet-Draft OSPF LLS Extensions for Interface ID May 2017 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Interface ID Exchange using TE Opaque LSA . . . . . . . . . . 2 3. Interface ID Exchange using OSPF LLS . . . . . . . . . . . . 3 3.1. Local Interface Identifier TLV . . . . . . . . . . . . . 3 4. Backward Compatibility with RFC 4203 . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 4 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 9. Normative References . . . . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction Every interface is assigned an Interface ID, which uniquely identifies the interface on the router. For example, some implementations MAY be able to use the MIB-II IfIndex [RFC2863] as the Interface ID. Local/Remote Interface Identifiers MAY be flooded by OSPF [RFC2328] as defined in [RFC4203]. From the perspective of the advertising router, the Local Interface Identifier is a known value, however the Remote Interface Identifier needs to be learnt before it can be advertised. [RFC4203] suggests to use TE Link Local LSA [RFC3630] to communicate Local Interface Identifier to neighbors on the link. Though such mechanism works, it has some drawbacks. This draft proposes an extension to OSPF link-local signaling (LLS) [RFC5613] to advertise the Local Interface Identifier. 2. Interface ID Exchange using TE Opaque LSA Usage of the Link Local TE Opaque LSA to propagate the Local Interface Identifier to the neighbors on the link is described in [RFC4203]. This mechanism has following problems: LSAs can only be flooded over an existing adjacency that is in Exchange state or greater. The adjacency state machine progresses Psenak, et al. Expires November 25, 2017 [Page 2] Internet-Draft OSPF LLS Extensions for Interface ID May 2017 independently on each side of the adjacency and, as such, may reach the Full state on one side before the TE Link Opaque LSA arrives. The consequence is that link can be initially advertised without the Remote Interface Identifier. Later when the TE Link Opaque LSA arrives, the link must be advertised again, this time with the valid Remote Interface Identifier. Implementation may choose to wait before advertising the link, but there is no guarantee that the neighbor will ever advertise the TE Link Opaque LSA with the Interface Identifier. In summary, the existing mechanism does not guarantee that Remote Interface Identifier is known at the time the link is advertised. TE Opaque LSA is defined for MPLS Traffic Engineering, but the knowledge of the Remote Interface Identifier is useful for other cases where MPLS TE is not used. One example is the lack of valid 2-way connectivity check for remote parallel point-to-point links in OSPF. In such case, TE Opaque LSAs are not exchanged solely for 2-way connectivity correctness. 3. Interface ID Exchange using OSPF LLS To address the problems described earlier and to allow the Interface Identifiers exchange to be part of the neighbor discovery process, we propose to extend OSPF link-local signaling to advertise the Local Interface Identifier in OSPF Hello packets. 3.1. Local Interface Identifier TLV The Local Interface Identifier TLV is a new LLS TLV. It has following format: 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local Interface Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where: Type: TBD, suggested value 18 Length: 4 octet Local Interface Identifier: The value of the local Interface Identifier. Psenak, et al. Expires November 25, 2017 [Page 3] Internet-Draft OSPF LLS Extensions for Interface ID May 2017 Local Interface Identifier TLV MUST be present in all Hello packets on all link types, except packets that are sent to the remote end of the virtual-link. 4. Backward Compatibility with RFC 4203 Implementations which support Local Interface ID signalling using LLS MUST prefer the Local Interface ID value received through LLS over the value received through the Link Local TE Opaque LSAs. Implementations which also support the Local Interface ID signalling via Link Local TE Opaque LSA MAY continue to do so to ensure backward compatibility and they MUST signal the same local interface id via both mechanisms. During the rare conditions, when the Local Interface ID changes, a timing interval may exist, where the received values of the Local Interface ID advertised through LLS and Link Local TE Opaque LSA may differ. Such situation is temporary and received values via both mechanisms should become equal as soon as the next Hello and/or Link Local TE Opaque LSA is re-generated by the originator. 5. IANA Considerations This specification updates Link Local Signalling TLV Identifiers registry. Following values is allocated: o 18 - Local Interface Identifier TLV 6. Security Considerations Implementations must assure that malformed LLS TLV and Sub-TLV permutations do not result in errors which cause hard OSPF failures. 7. Contributors 8. Acknowledgements Thanks to Tony Przygienda for his extensive review and useful comments. 9. Normative References Psenak, et al. Expires November 25, 2017 [Page 4] Internet-Draft OSPF LLS Extensions for Interface ID May 2017 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, DOI 10.17487/RFC2328, April 1998, . [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000, . [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, DOI 10.17487/RFC3630, September 2003, . [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, . [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, . [RFC5613] Zinin, A., Roy, A., Nguyen, L., Friedman, B., and D. Yeung, "OSPF Link-Local Signaling", RFC 5613, DOI 10.17487/RFC5613, August 2009, . Authors' Addresses Peter Psenak (editor) Cisco Systems, Inc. Apollo Business Center Mlynske nivy 43 Bratislava 821 09 Slovakia Email: ppsenak@cisco.com Psenak, et al. Expires November 25, 2017 [Page 5] Internet-Draft OSPF LLS Extensions for Interface ID May 2017 Ketan Jivan Talaulikar Cisco Systems, Inc. S.No. 154/6, Phase I, Hinjawadi PUNE, MAHARASHTRA 411 057 India Email: ketant@cisco.com Wim Henderickx Nokia Copernicuslaan 50 Antwerp 2018 BE Email: wim.henderickx@nokia.com Padma Pillay-Esnault Huawei 2330 Central Expressway Santa Clara, CA 95050 USA Email: padma@huawei.com Psenak, et al. Expires November 25, 2017 [Page 6]