PCE WG Quan Xiong Internet-Draft Fangwei Hu Intended status: Standards Track Shuangping Zhan Expires: September 6, 2018 ZTE Corporation March 5, 2018 PCEP extensions for SR-TP draft-xiong-pce-pcep-extension-sr-tp-00.txt Abstract This document proposes a set of extensions to PCEP for Segment Routing in MPLS Transport Profile (SR-TP) networks and defines a mechanism to create the bi-directional SR tunnel in SR-TP networks with PCE. 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 https://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 September 6, 2018. Copyright Notice Copyright (c) 2018 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 (https://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. Quan Xiong, et al. Expires September 6, 2018 [Page 1] Internet-Draft PCEP extensions for SR-TP March 2018 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. The SR-TP Architecture with PCE . . . . . . . . . . . . . . . 3 3. PCEP extensions for SR-TP . . . . . . . . . . . . . . . . . . 4 3.1. Bi-directional LSP extension . . . . . . . . . . . . . . 4 3.1.1. The B flag in SRP Object . . . . . . . . . . . . . . 4 3.2. SR-TP ERO extension . . . . . . . . . . . . . . . . . . . 4 3.3. Processing Rules . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 7.1. Informative References . . . . . . . . . . . . . . . . . 6 7.2. Normative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction The Path Computation Element Communication Protocol (PCEP) defined in [RFC5440] provides mechanisms for Path Computation Elements (PCEs) to perform path computations in response to Path Computation Clients (PCCs) requests. [I-D.ietf-pce-segment-routing] proposes extensions to PCEP that allow a stateful PCE to compute Traffic Engineering (TE) paths in segment routing (SR) networks. But it is applicable to Multi-protocol Label Switching (MPLS) networks. [I-D.hu-spring-sr-tp-use-case] describes the use case of SR tunnel to be deployed in MPLS Transport Profile (SR-TP) network. It is required to extend the PCEP protocol to meet the new requirement for SR-TP. This document proposes a set of extensions to PCEP for Segment Routing in MPLS Transport Profile (SR-TP) networks and defines a mechanism to create the bi-directional SR tunnel in SR-TP networks with PCE. 1.1. 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 [RFC2119]. Quan Xiong, et al. Expires September 6, 2018 [Page 2] Internet-Draft PCEP extensions for SR-TP March 2018 1.2. Terminology The terminology is defined as [RFC5440], [I-D.ietf-pce-segment-routing] and [I-D.hu-spring-sr-tp-use-case]. 2. The SR-TP Architecture with PCE As described in [I-D.hu-spring-sr-tp-use-case], in SR-TP networks, the centralized controller may calculate the end to end SR paths, and creates the ordered segment list. The centralized controller may be replaced to PCE as the Figure 1 shown. The PCE can calculate the SR paths and initiate a SR path on a PCC. | | V +---+--+ +--------------+ PCE +---------------+ | +---+--+ | +-------|-------------------------------------|--------+ | | SR-TP network | | | | | | | +---+--+ +---+--+ +---+--+ | | | A +-----------+ B +-----------+ C + | | +------+ +------+ +------+ | | | +------------------------------------------------------+ +------------+ +------------+ | Label A | | Label C | +------------+ +------------+ | ... | | ... | +------------+ +------------+ | Label C | | Label A | +------------+ +------------+ | Path Label | | Path Label | +------------+ +------------+ Figure 1 The SR-TP Architecture with PCE It is required to support bi-direction tunnel to meet the requirement of SP-TP networks. A label named Path segment at both ends of the paths was defined to identify the direction of the SR paths as described in [I-D.cheng-spring-mpls-path-segment]. It mainly aims to bind two unidirectional SR paths to a single bi-directional tunnel. Quan Xiong, et al. Expires September 6, 2018 [Page 3] Internet-Draft PCEP extensions for SR-TP March 2018 3. PCEP extensions for SR-TP 3.1. Bi-directional LSP extension 3.1.1. The B flag in SRP Object The format of the SRP object is defined in [RFC8231] and included here for easy reference with the addition of the new B flag. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags |B| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SRP-ID-number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // Optional TLVs // | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 The SRP Object Format A new flag is defined to indicate a bi-directional LSP operation initiated by the PCE: B(Bi-directional -- 1 bit):when set, the PCE specifies that the request relates to a bi-directional TE LSP that has the same traffic engineering requirements including fate sharing, protection and restoration, LSRs, TE links, and resource requirements (e.g., latency and jitter) in each direction. When cleared, the TE LSP is unidirectional. 3.2. SR-TP ERO extension As described in [I-D.hu-spring-sr-tp-use-case], it is required to support bi-directional tunnel to meet the requirement of SP-TP networks. But it is the uni-directional tunnel for SR and engineering traffic network as discussed in [I-D.ietf-pce-segment-routing]. The SR path is carried in the Segment Routing Explicit Route Object (SR-ERO), which consists of a sequence of SR subobjects. This document proposes the extension of the SR-ERO Subobject to carry the bi-directional tunnel information as the Figure 3 shown. Quan Xiong, et al. Expires September 6, 2018 [Page 4] Internet-Draft PCEP extensions for SR-TP March 2018 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |L| Type | Length | ST | Flags |R|F|S|C|M| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // Path Label information (variable) // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3 Extension of SR-ERO Subobject 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Path Label | TC |S| TTL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4 Path Label information ST (SID Type -- 4 bit):TBD, indicates the type of information associated with the Path Label contained in the object body. when the ST indicates the Path Label type, the NAI is filled with the Path Label information as the Figure 4 shown. R (Reverse Flag -- 1 bit): indicates the SR path direction, when it is clear, it indicates the forward direction and when it is set, it indicates the reverse direction. The definition of other fields is the same with [I-D.ietf-pce-segment-routing]. 3.3. Processing Rules As discussed in [I-D.cheng-spring-mpls-path-segment], the bi- directional SR tunnel is created from two binding unidirectional SR paths. As defined in [RFC8281], the stateful PCE calculates the SR paths and initiates the bi-directional LSP with Initiate Request message (PCInitiate). The B bit in SRP Object MUST be set and the two unidirectional SR paths may be computed from the forward and reverse direction and sent to the source and destination PCC respectively in SR-ERO object. The path labels which binding the paths may be generated in PCE and sent to the related PCC carried in the bottom of the SR-ERO. When the PCCs at both ends receiving the PCInitiate message with the labels in Quan Xiong, et al. Expires September 6, 2018 [Page 5] Internet-Draft PCEP extensions for SR-TP March 2018 SR-ERO subobjects, they may forward the packets from bi-directional tunnel in SR-TP networks. 4. Security Considerations TBD. 5. IANA Considerations TBD. 6. Acknowledgements TBD. 7. References 7.1. Informative References [I-D.hu-spring-sr-tp-use-case] hu, f., Xiong, Q., Mirsky, G., and W. Cheng, "Segment Routing Transport Profile Use Case", draft-hu-spring-sr- tp-use-case-01 (work in progress), March 2018. 7.2. Normative References [I-D.cheng-spring-mpls-path-segment] Cheng, W., Wang, L., Li, H., Chen, M., Zigler, R., and S. Zhan, "Path Segment in MPLS Based Sement Routing Network", draft-cheng-spring-mpls-path-segment-01 (work in progress), March 2018. [I-D.ietf-pce-segment-routing] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., and J. Hardwick, "PCEP Extensions for Segment Routing", draft-ietf-pce-segment-routing-11 (work in progress), November 2017. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, DOI 10.17487/RFC5440, March 2009, . Quan Xiong, et al. Expires September 6, 2018 [Page 6] Internet-Draft PCEP extensions for SR-TP March 2018 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path Computation Element Communication Protocol (PCEP) Extensions for Stateful PCE", RFC 8231, DOI 10.17487/RFC8231, September 2017, . [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path Computation Element Communication Protocol (PCEP) Extensions for PCE-Initiated LSP Setup in a Stateful PCE Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, . Authors' Addresses Quan Xiong ZTE Corporation No.6 Huashi Park Rd Wuhan, Hubei 430223 China Phone: +86 27 83531060 Email: xiong.quan@zte.com.cn Fangwei Hu ZTE Corporation No.889 Bibo Rd Shanghai 201203 China Phone: +86 21 68896273 Email: hu.fangwei@zte.com.cn Shuangping Zhan ZTE Corporation Liuxian Rd Shenzhen 518057 China Phone: +86 755 26773770 Email: zhan.shuangping@zte.com.cn Quan Xiong, et al. Expires September 6, 2018 [Page 7]