Network Working Group Z. Li Internet-Draft X. Chen Intended status: Standards Track N. Wu Expires: May 3, 2017 Huawei Technologies October 30, 2016 PCEP Link-State extensions for Segment Routing draft-li-pce-pcep-ls-sr-extension-01 Abstract Segment Routing leverages source routing. A node steers a packet through a controlled set of instructions, called segments, by prepending the packet with an SR header. A segment can represent any instruction, topological or service-based. SR allows to enforce a flow through any topological path and service chain while maintaining per-flow state only at the ingress node of the SR domain. IGP protocols have been extended to advertise the segments. Because of IGP's propagation scope limitation, it is not suited for IGP to signal paths that span across AS borders. This document introduces extensions of PCEP-LS to solve the problem without the similar limitation. 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 May 3, 2017. Li, et al. Expires May 3, 2017 [Page 1] Internet-DrafPCEP Link-State extensions for Segment Routing October 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 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. PCEP extensions for Segment Routing . . . . . . . . . . . . . 3 2.1. Node Attribute TLVs . . . . . . . . . . . . . . . . . . . 3 2.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . . . 3 2.3. Prefix Attribute TLVs . . . . . . . . . . . . . . . . . . 4 3. Operational Considerations . . . . . . . . . . . . . . . . . 4 3.1. Segment Routing report . . . . . . . . . . . . . . . . . 4 3.2. Tunnel Segment Identifier . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction Segment Routing [I-D.ietf-spring-segment-routing] leverages source routing. A node steers a packet through a controlled set of instructions, called segments, by prepending the packet with an SR header. A segment can represent any instruction, topological or service-based. SR allows to enforce a flow through any topological path and service chain while maintaining per-flow state only at the ingress node of the SR domain. IGP protocols have been extended to advertise the segments. Because of IGP's propagation scope limitation, it is not suited for IGP to signal paths that span across AS borders. Li, et al. Expires May 3, 2017 [Page 2] Internet-DrafPCEP Link-State extensions for Segment Routing October 2016 In order to fulfill the need for applications that require visibility of SR paths across IGP areas or even across ASes, this document defines extensions for the mechanism introduced in [I-D.dhodylee-pce-pcep-ls] to propagate SR information in those scenarios that have no IGP SR extension or BGP-LS running. 2. PCEP extensions for Segment Routing PCEP-LS [I-D.dhodylee-pce-pcep-ls] introduces new message type and new object to accommodate link-state information in PCEP. This document defines new additional TLVs to map segment routing information. The value portion of these new TLVs can reuse the structure defined in [I-D.ietf-isis-segment-routing-extensions]. 2.1. Node Attribute TLVs Some new optional, non-transitive node attribute TLVs are defined for carrying segment routing information and are listed below: +--------------+-----------------------+----------+-----------------------+ |TLV Code Point| Description | Length | Value defined | +--------------+-----------------------+----------+-----------------------+ | TBD1 | SID/Label Binding | variable | [ISIS-SR]#section2.4 | +--------------+-----------------------+----------+-----------------------+ | TBD2 | SR-Capabilities | variable | [ISIS-SR]#section3.1 | +--------------+-----------------------+----------+-----------------------+ | TBD3 | SR-Algorithm | variable | [ISIS-SR]#section3.2 | +--------------+-----------------------+----------+-----------------------+ [ISIS-SR]: https://datatracker.ietf.org/doc/draft-ietf-isis-segment- routing-extensions/ Table 1: Node Attribute TLVs 2.2. Link Attribute TLVs Some new optional, non-transitive link attribute TLVs are defined for carrying segment routing information and are listed below: +--------------+-----------------------+----------+-----------------------+ |TLV Code Point| Description | Length | Value defined | +--------------+-----------------------+----------+-----------------------+ | TBD4 | Adjacency Segment | variable | [ISIS-SR]#section2.2.1| +--------------+-----------------------+----------+-----------------------+ | TBD5 | LAN Adjacency Segment | variable | [ISIS-SR]#section2.2.2| +--------------+-----------------------+----------+-----------------------+ | TBD6 | Tunnel Segment | variable | | +--------------+-----------------------+----------+-----------------------+ Li, et al. Expires May 3, 2017 [Page 3] Internet-DrafPCEP Link-State extensions for Segment Routing October 2016 [ISIS-SR]: https://datatracker.ietf.org/doc/draft-ietf-isis-segment- routing-extensions/ Table 2: Link Attribute TLVs 2.3. Prefix Attribute TLVs A new optional, non-transitive link attribute TLVs are defined for carrying segment routing information and are listed below: +--------------+-----------------------+----------+-----------------------+ |TLV Code Point| Description | Length | Value defined | +--------------+-----------------------+----------+-----------------------+ | TBD7 | Prefix Segment | variable | [ISIS-SR]#section2.1.2| +--------------+-----------------------+----------+-----------------------+ [ISIS-SR]: https://datatracker.ietf.org/doc/draft-ietf-isis-segment- routing-extensions/ Table 3: Prefix Attribute TLVs 3. Operational Considerations 3.1. Segment Routing report The procedure for segment routing information reporting from PCC to PCE will follow those defined in [I-D.dhodylee-pce-pcep-ls]. 3.2. Tunnel Segment Identifier Tunnel Segment introduced in [I-D.li-spring-tunnel-segment] is used to identify a tunnel of any kind in a segment routing network. It is originated by the tunnel ingress node and one SID is allocated and attached to it either locally or globally. 4. IANA Considerations TBD. 5. Security Considerations TBD. 6. Acknowledgements TBD. Li, et al. Expires May 3, 2017 [Page 4] Internet-DrafPCEP Link-State extensions for Segment Routing October 2016 7. References 7.1. Normative References [I-D.dhodylee-pce-pcep-ls] Dhody, D., Lee, Y., and D. Ceccarelli, "PCEP Extension for Distribution of Link-State and TE Information.", draft- dhodylee-pce-pcep-ls-06 (work in progress), September 2016. [I-D.ietf-isis-segment-routing-extensions] Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., Litkowski, S., Decraene, B., and j. jefftant@gmail.com, "IS-IS Extensions for Segment Routing", draft-ietf-isis- segment-routing-extensions-08 (work in progress), October 2016. [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-09 (work in progress), July 2016. [I-D.li-spring-tunnel-segment] Li, Z. and N. Wu, "Tunnel Segment in Segment Routing", draft-li-spring-tunnel-segment-01 (work in progress), March 2016. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . 7.2. Informative References [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, DOI 10.17487/RFC5440, March 2009, . Authors' Addresses Zhenbin Li Huawei Technologies Huawei Bld., No.156 Beiqing Rd. Beijing 100095 China Email: lizhenbin@huawei.com Li, et al. Expires May 3, 2017 [Page 5] Internet-DrafPCEP Link-State extensions for Segment Routing October 2016 Xia Chen Huawei Technologies Huawei Bld., No.156 Beiqing Rd. Beijing 100095 China Email: jescia.chenxia@huawei.com Nan Wu Huawei Technologies Huawei Bld., No.156 Beiqing Rd. Beijing 100095 China Email: eric.wu@huawei.com Li, et al. Expires May 3, 2017 [Page 6]