TEAS Working Group R. Gandhi, Ed. Internet-Draft Cisco Systems Intended Status: Standards Track H. Shah Expires: August 18, 2017 Ciena Jeremy Whittaker Verizon February 14, 2017 Fast Reroute Procedures For Associated Co-routed Bidirectional Label Switched Paths (LSPs) draft-gandhishah-teas-assoc-corouted-bidir-03 Abstract Resource Reservation Protocol (RSVP) association signaling can be used to bind two unidirectional LSPs into an associated bidirectional LSP. In packet transport networks, there are requirements where the reverse unidirectional LSP of an associated bidirectional LSP needs to follow the same path as its forward unidirectional LSP. In addition, the associated bidirectional LSP needs to maintain co-routed-ness even after a failure event in the network. This document describes fast reroute procedures for associated bidirectional LSPs that ensure the traffic flows on a co-routed path after a failure event for single-sided provisioning model. 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." Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the Gandhi, et al. Expires August 18, 2017 [Page 1] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 2.1. Key Word Definitions . . . . . . . . . . . . . . . . . . . 3 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2.2.1. Reverse Co-routed Unidirectional LSPs . . . . . . . . 4 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Co-routed Bidirectional LSP Association . . . . . . . . . 4 3.2. Fast Reroute Bypass Tunnel Assignment . . . . . . . . . . 5 4. Signaling Procedure . . . . . . . . . . . . . . . . . . . . . 6 4.1. Co-routed Bidirectional LSP Association . . . . . . . . . 6 4.2. Fast Reroute For Associated Co-routed Bidirectional LSP . 7 5. Message and Object Definitions . . . . . . . . . . . . . . . . 7 5.1. Extended ASSOCIATION Object . . . . . . . . . . . . . . . 7 6. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 9.1. Normative References . . . . . . . . . . . . . . . . . . . 10 9.2. Informative References . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Gandhi, et al. Expires August 18, 2017 [Page 2] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 1. Introduction The Resource Reservation Protocol (RSVP) (Extended) ASSOCIATION Object is specified in [RFC6780] which can be used generically to associate (G)Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs). [RFC7551] defines mechanisms for binding two point-to- point unidirectional LSPs [RFC3209] into an associated bidirectional LSP. There are two models described in [RFC7551] for provisioning an associated bidirectional LSP, single-sided and double-sided. In this document, only the single-sided provisioned associated bidirectional LSPs are considered for co-routed-ness. The MPLS Transport Profile (TP) [RFC6370] architecture facilitates the co-routed bidirectional LSP by using the GMPLS extensions [RFC3473] to achieve congruent paths. However, the RSVP association signaling allows to enable co-routed bidirectional LSPs without having to deploy GMPLS extensions in the existing networks. The association signaling also allows to take advantage of the existing Traffic Engineering (TE) mechanisms in the network. In packet transport networks, there are requirements where the reverse LSP of an associated bidirectional LSP needs to follow the same path as its forward LSP [RFC6373]. In addition, the associated bidirectional LSP needs to maintain co-routed-ness even after a failure event in the network. [GMPLS-FRR] defines fast reroute procedure for GMPLS signaled LSPs to co-ordinate bypass tunnel assignments in the forward and reverse directions. The mechanisms defined in [GMPLS-FRR] can be used for fast reroute of the associated bidirectional LSPs. This document describes fast reroute procedures for associated co-routed bidirectional LSPs to ensure the traffic flows on the co-routed path in the forward and reverse direction of the LSP after a failure event. 2. Conventions Used in This Document 2.1. Key Word Definitions 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]. 2.2. Terminology The reader is assumed to be familiar with the terminology in Gandhi, et al. Expires August 18, 2017 [Page 3] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 [RFC2205], [RFC3209], [RFC7551], and [RFC4090]. 2.2.1. Reverse Co-routed Unidirectional LSPs Two reverse unidirectional point-to-point (P2P) LSPs are setup in the opposite directions between a pair of source and destination nodes to form an associated bidirectional LSP. A reverse unidirectional LSP originates on the same node where the forward unidirectional LSP terminates, and it terminates on the same node where the forward unidirectional LSP originates. A reverse co-routed unidirectional LSP traverses along the same path of the forward direction unidirectional LSP in the opposite direction. 3. Overview As specified in [RFC7551], in the single-sided provisioning case, the RSVP TE tunnel is configured only on one endpoint node. An LSP for this tunnel is initiated by the originating endpoint with (Extended) ASSOCIATION Object containing Association Type set to "single-sided associated bidirectional LSP" and REVERSE_LSP Object inserted in the Path message. The remote endpoint then creates the corresponding reverse TE tunnel and signals the reverse LSP in response using the information from the REVERSE_LSP Object and other objects present in the received Path message. The reverse LSP thus created may or may not be congruent and follow the same path as its forward LSP. The single-sided associated co-routed bidirectional LSP signaled using the mechanisms defined in [RFC7551] requires solutions for the following issues for fast reroute to ensure co-routed-ness. 3.1. Co-routed Bidirectional LSP Association Multiple forward and reverse LSPs of a bidirectional LSP may be present at mid-point nodes with identical (Extended) ASSOCIATION Objects. For example, this can occur while RSVP states are timing out after fast reroute, or during recovery phase in RSVP graceful restart. This creates an ambiguity at mid-point nodes to identify the correct associated LSP pair for fast reroute bypass assignment. Gandhi, et al. Expires August 18, 2017 [Page 4] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 LSP3 --> LSP3 --> LSP1 --> LSP1 --> LSP1 --> +-----+ +-----+ +-----+ +-----+ | A +-----------+ B +-----------+ C +-----------+ D | +-----+ +--+--+ +--+--+ +-----+ <-- LSP2 | <-- LSP2 | <-- LSP2 <-- LSP4 | | <-- LSP4 | | | LSP3 --> | +--+--+ +--+--+ | E +-----------+ F | +-----+ +-----+ <-- LSP4 Figure 1: Multiple LSPs with Matching (Extended) ASSOCIATION Object As shown in Figure 1, LSP1 and LSP2 are an associated co-routed LSP pair, similarly LSP3 and LSP4 are an associated co-routed LSP pair, both pairs belong to the same associated bidirectional LSP and carry identical (Extended) ASSOCIATION Objects. In this example, mid-point nodes B and C may mistakenly associate LSP1 with non co-routed reverse LSP4 instead of co-routed reverse LSP3 due to the matching (Extended) ASSOCIATION Objects. 3.2. Fast Reroute Bypass Tunnel Assignment In order to ensure that the traffic flows on the co-routed path after a link or node failure on the LSP path, the mid-point Point of Local Repair (PLR) nodes need to assign correct bidirectional co-routed bypass tunnels for fast reroute. Such bypass assignment requires co-ordination between the forward and reverse direction PLR nodes when more than one bypass tunnels are present on a node. +-----+ +-----+ | G +-----------+ H | +--+--+ +--+--+ | | | | LSP1 --> | LSP1 --> | LSP1 --> +-----+ +--+--+ +--+--+ +-----+ | A +-----------+ B +-----------+ C +-----------+ D | +-----+ +--+--+ +--+--+ +-----+ <-- LSP2 | <-- LSP2 | <-- LSP2 | | | | +--+--+ +--+--+ | E +-----------+ F | +-----+ +-----+ Gandhi, et al. Expires August 18, 2017 [Page 5] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 Figure 2: Multiple Bidirectional Bypass Tunnels As shown in Figure 2, there are two bypass tunnels available, one on path B-G-H-C and other on path B-E-F-C. In order to ensure co- routed-ness, the mid-point PLR nodes B and C need to co-ordinate bypass tunnel assignment to ensure that traffic in both directions flow through either on path B-G-H-C or path B-E-F-C, after the link B-C failure. 4. Signaling Procedure 4.1. Co-routed Bidirectional LSP Association In order to ensure co-routed-ness, Extended ASSOCIATION Object is used in the RSVP Path message using the procedures defined in [RFC7551] as following. o The originating head-end node MUST add Extended ASSOCIATION Object with Association Type set to "single-sided associated bidirectional LSP" and unique Extended Association ID for each associated forward and reverse LSP pair forming the bidirectional LSP. As an example, a node MAY set the Extended Association ID to the values specified in Section 5.1 of this document. As specified in [RFC7551], the remote endpoint copies the contents of the received Extended ASSOCIATION Object including the Extended Association ID in the RSVP Path message of the reverse LSP's Extended ASSOCIATION Object. o The originating head-end node MUST add an EXPLICIT_ROUTE Object (ERO) in the REVERSE_LSP Object by using the hops traversed by the forward LSP in the reverse order to ensure that reverse LSP follows the same path as forward direction LSP in the opposite direction. As specified in [RFC7551], the remote endpoint builds the ERO of the reverse LSP using the ERO from the received REVERSE_LSP Object of the forward LSP. o When an ERO contains one or more loose next-hop(s), the originating head-end MUST add RECORD_ROUTE Object (RRO) in the Path message of the forward LSP to record the hops traversed by the LSP. The remote endpoint SHOULD use the recorded hops from the RRO in the forward LSP to expand the loose next-hop(s), to ensure that the reverse LSP follows the same path as the forward LSP. Gandhi, et al. Expires August 18, 2017 [Page 6] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 4.2. Fast Reroute For Associated Co-routed Bidirectional LSP The mechanisms defined in [GMPLS-FRR] can be used for associated co-routed bidirectional LSP to ensure the traffic flows on a co-routed path in the forward and reverse directions after a link or node failure as following. o As described in [GMPLS-FRR], BYPASS_ASSIGNMENT subobject is signaled in the RRO of the Path message to co-ordinate bypass tunnel assignment between the forward and reverse direction PLR nodes. A BYPASS_ASSIGNMENT subobject MUST be added by the forward direction PLR node in the Path message of the originating LSP to indicate the bypass tunnel assigned. o The forward direction PLR node always initiates the bypass tunnel assignment for the originating LSP. The reverse direction PLR (forward direction LSP Merge Point (MP)) node simply reflects the bypass tunnel assignment for the reverse direction LSP. o After a link or node failure, the PLR nodes in both forward and reverse directions trigger fast reroute independently using the procedures defined in [RFC4090]. o When using a node protection bypass tunnel, asymmetry of paths can occur in the forward and reverse directions of the bidirectional LSP after a link failure [GMPLS-FRR]. This is corrected using the re-corouting procedure defined in [GMPLS-FRR]. Unlike GMPLS LSPs, the asymmetry of paths does not result in RSVP soft-state time-out with the associated bidirectional LSPs. 5. Message and Object Definitions 5.1. Extended ASSOCIATION Object The Extended Association ID in the Extended ASSOCIATION Object can be set by the originating node to the value specified as following when the associated bidirectional LSP is co-routed. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 LSP Source Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | LSP-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : Gandhi, et al. Expires August 18, 2017 [Page 7] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 : Variable Length ID : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: IPv4 Extended Association ID 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | IPv6 LSP Source Address | + + | (16 bytes) | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | LSP-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : : : Variable Length ID : : : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: IPv6 Extended Association ID LSP Source Address IPv4/IPv6 source address of the originating LSP. LSP-ID 16-bits LSP-ID of the originating LSP. Variable Length ID Variable length ID inserted by the originating node of the Associated co-routed bidirectional LSP. 6. Compatibility This document describes the procedures for fast reroute for associated co-routed bidirectional LSPs. Operators wishing to use this function SHOULD ensure that it is supported on the nodes on the Gandhi, et al. Expires August 18, 2017 [Page 8] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 LSP path. 7. Security Considerations This document uses signaling mechanisms defined in [RFC7551] and [GMPLS-FRR] and does not introduce any additional security considerations other than already covered in [RFC7551], [GMPLS-FRR] and the MPLS/GMPLS security framework [RFC5920]. 8. IANA Considerations This document does not make any request for IANA action. Gandhi, et al. Expires August 18, 2017 [Page 9] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. [RFC6780] Berger, L., Le Faucheur, F., and A. Narayanan, "RSVP Association Object Extensions", RFC 6780, October 2012. [RFC7551] Zhang, F., Ed., Jing, R., and Gandhi, R., Ed., "RSVP-TE Extensions for Associated Bidirectional LSPs", RFC 7551, May 2015. [GMPLS-FRR] Taillon, M., Saad, T., Ed., Gandhi, R., Ed., Ali, Z., Bhatia, M., "Extensions to Resource Reservation Protocol For Fast Reroute of Traffic Engineering GMPLS LSPs", draft-ietf-teas-gmpls-lsp-fastreroute, work in progress. 9.2. Informative References [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS Networks", RFC 5920, July 2010. [RFC6370] Bocci, M., Swallow, G., and E. Gray, "MPLS Transport Profile (MPLS-TP) Identifiers", RFC 6370, September 2011. [RFC6373] Andersson, L., Berger, L., Fang, L., Bitar, N., and E. Gray, "MPLS Transport Profile (MPLS-TP) Control Plane Framework", RFC 6373, September 2011. Gandhi, et al. Expires August 18, 2017 [Page 10] Internet-Draft FRR For Co-routed Bidirectional LSP February 14, 2017 Authors' Addresses Rakesh Gandhi (editor) Cisco Systems, Inc. EMail: rgandhi@cisco.com Himanshu Shah Ciena EMail: hshah@ciena.com Jeremy Whittaker Verizon EMail: jeremy.whittaker@verizon.com Gandhi, et al. Expires August 18, 2017 [Page 11]