Network Working Group S. Previdi, Ed. Internet-Draft L. Ginsberg Intended status: Standards Track C. Filsfils Expires: November 18, 2016 Cisco Systems, Inc. May 17, 2016 Segment Routing IPv6 Prefix-SID draft-previdi-isis-ipv6-prefix-sid-02 Abstract This document defines the Segment Routing IPv6-Prefix-SID sub-TLV. This new sub-TLV allows to specify which of the prefixes advertised by a node are to be used as Segment Routing Identifiers (SID) for the IPv6 data plane. 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 18, 2016. Copyright Notice Copyright (c) 2016 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 (http://trustee.ietf.org/license-info) in effect on the date of Previdi, et al. Expires November 18, 2016 [Page 1] Internet-Draft IPv6 Prefix-SID May 2016 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. IPv6 Prefix SID . . . . . . . . . . . . . . . . . . . . . . . 2 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 6.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction With Segment Routing (SR)[I-D.ietf-spring-segment-routing], a node steers a packet through an ordered list of instructions, called segments. Segments are identified through Segment Identifiers (SIDs) that are advertised by routing protocols. The IS-IS extensions for SR information advertisement are defined in [I-D.ietf-isis-segment-routing-extensions]. Segment Routing can be directly applied to the IPv6 data plane through the use of the Segment Routing Header defined in [I-D.ietf-6man-segment-routing-header]. When applied to the IPv6 data plane, the SID is represented by an IPv6 address. This document defines a new IS-IS Prefix sub-TLV where information related to the IPv6 address used as SR IPv6 SID is conveyed. 2. IPv6 Prefix SID When SR is applied to the IPv6 data plane, Segment Identifiers (SIDs) are IPv6 addresses. In a router, it is desirable to identify which of the local prefixes can be used as SIDs. Also, and in order to provide the same functionalities defined in [I-D.ietf-spring-segment-routing] and according to [I-D.ietf-isis-segment-routing-extensions], a new sub-TLV is defined: the IPv6-Prefix-SID sub-TLV. Previdi, et al. Expires November 18, 2016 [Page 2] Internet-Draft IPv6 Prefix-SID May 2016 The IPv6-Prefix-SID sub-TLV is attached to an IPv6 prefix advertised by a node and MAY be present in any of the following TLVs: TLV-236 (IPv6) defined in [RFC5308]. TLV-237 (MT-IPv6) defined in [RFC5120]. The IPv6-Prefix-SID sub-TLV is optional, MAY appear only once for a given prefix and has the 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 | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Algorithm | // +-+-+-+-+-+-+-+-+ Sub-TLVs // // // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where: Type: To be assigned by IANA (suggested value 5). Length: 3 + length of sub-TLVs. Flags: 2 octet field of flags. None of them is defined at this stage. Algorithm: as defined in [I-D.ietf-isis-segment-routing-extensions]. Sub-TLVs: additional information encoded into the IPv6-Prefix-SID Sub-TLV. Currently, no sub-TLVs are defined yet. A prefix with an attached IPv6-Prefix-SID sub-TLV is defined as an SR-IPv6 Prefix SID. If the prefix is to be used as a Node-SID (according to [I-D.ietf-isis-segment-routing-extensions]) then the following applies: o The IPv6 prefix MUST be advertised with the IPv6-Prefix-SID sub- TLV attached. o The Extended Reachability Attribute Flags sub-TLV defined in [RFC7794] MUST be attached to the prefix and the N-flag MUST be set. Previdi, et al. Expires November 18, 2016 [Page 3] Internet-Draft IPv6 Prefix-SID May 2016 When a router has attached an IPv6-Prefix-SID sub-TLV to a prefix, it implies that the router supports the Segment Routing Header (SRH, defined in [I-D.ietf-6man-segment-routing-header] and its associated procedures for packets destined to the advertised prefix. A router receiving an IPv6-Prefix-SID from a remote node and with an algorithm value that such remote node has not advertised in the SR- Capability sub-TLV (as defined in [I-D.ietf-isis-segment-routing-extensions]) MUST ignore the IPv6- Prefix-SID sub-TLV. 3. IANA Considerations This document makes the following registrations in the "sub-TLVs for TLV 135, 235, 236 and 237" registry. Type: TBD (suggested value 5) Description: IPv6 Prefix Segment Identifier TLV 135: no TLV 235: no TLV 236: yes TLV 237: yes Reference: This document (Section 2) 4. Security Considerations This document doesn't introduce new security considerations. 5. Acknowledgements The authors would like to thank Nagendra Kumar for his review of this document. 6. References 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Previdi, et al. Expires November 18, 2016 [Page 4] Internet-Draft IPv6 Prefix-SID May 2016 [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)", RFC 5120, DOI 10.17487/RFC5120, February 2008, . [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, DOI 10.17487/RFC5308, October 2008, . [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, March 2016, . 6.2. Informative References [I-D.ietf-6man-segment-routing-header] Previdi, S., Filsfils, C., Field, B., Leung, I., Linkova, J., Kosugi, T., Vyncke, E., and D. Lebrun, "IPv6 Segment Routing Header (SRH)", draft-ietf-6man-segment-routing- header-01 (work in progress), March 2016. [I-D.ietf-isis-segment-routing-extensions] Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura, "IS-IS Extensions for Segment Routing", draft-ietf-isis-segment- routing-extensions-06 (work in progress), December 2015. [I-D.ietf-spring-segment-routing] Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", draft-ietf- spring-segment-routing-08 (work in progress), May 2016. Authors' Addresses Stefano Previdi (editor) Cisco Systems, Inc. Via Del Serafico, 200 Rome 00142 Italy Email: sprevidi@cisco.com Previdi, et al. Expires November 18, 2016 [Page 5] Internet-Draft IPv6 Prefix-SID May 2016 Les Ginsberg Cisco Systems, Inc. US Email: ginsberg@cisco.com Clarence Filsfils Cisco Systems, Inc. Brussels BE Email: cfilsfil@cisco.com Previdi, et al. Expires November 18, 2016 [Page 6]