MPLS Working Group Z. Ali Internet Draft Cisco Systems, Inc. Intended status: Standard Track November 02, 2008 Expires: May 02, 2009 Signaling RSVP-TE P2MP LSPs in an Inter-domain Environment draft-ali-mpls-inter-domain-p2mp-rsvp-te-lsp-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on May 02, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract Point-to-MultiPoint (P2MP) Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering Label Switched Paths (TE LSPs) may be established using signaling techniques described in [RFC4875]. However, [RFC4875] does not Expires May 2009 [Page 1] Internet-Draft draft-ali-mpls-inter-domain-p2mp-rsvp-te-lsp-01.txt address many issues that comes when a P2MP-TE LSP is signaled in a multi-domain networks. Specifically, one of the issues in multi-domain networks is how to allow computation of a loosely routed P2MP-TE LSP such that it is remerge free. This document provides a framework and required protocol extensions needed for establishing and controlling P2MP MPLS and GMPLS TE LSPs in multi-domain networks. This document borrows inter-domain TE terminology from [RFC4726], e.g., for the purposes of this document, a domain is considered to be any collection of network elements within a common sphere of address management or path computational responsibility. Examples of such domains include Interior Gateway Protocol (IGP) areas and Autonomous Systems (ASes). Conventions used in this document In examples, "C:" and "S:" indicate lines sent by the client and server respectively. 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. Table of Contents 1. Introduction...............................................2 2. Framework..................................................4 3. RSVP-TE signaling extensions...............................4 3.1. Multiple S2L Sub-LSPs in One Path Message.............4 3.2. Single S2L Sub-LSPs in One Path Message...............4 3.3. Grafting..............................................7 3.4. Crankback and Path Error..............................7 4. Security Considerations....................................7 5. IANA Considerations........................................8 6. References.................................................8 6.1. Normative References..................................8 6.2. Informative References................................8 Author's Addresses............................................8 Intellectual Property Statement...............................8 Disclaimer of Validity........................................9 1. Introduction [RFC4875] describes how to set up point-to-multipoint (P2MP) Traffic Engineering Label Switched Paths (TE LSPs) for use in Expires May 2009 [Page 2] Internet-Draft draft-ali-mpls-inter-domain-p2mp-rsvp-te-lsp-01.txt MultiProtocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks. As with all other RSVP controlled LSPs, P2MP LSP state is managed using RSVP messages. While the use of RSVP messages is mostly similar to their P2P counterpart, P2MP LSP state differs from P2P LSP in a number of ways. E.g., the P2MP LSP must also handle the state "re-merge" problem, see [RFC4875]. The term "re- merge" refers to the case of an ingress or transit node that creates a branch of a P2MP LSP, a re-merge branch that intersects the P2MP LSP at another node farther down the tree. This may occur due to such events as an error in path calculation, an error in manual configuration, or network topology changes during the establishment of the P2MP LSP. Consequently one of the requirements for signaling P2MP LSP is for the Ingress node to compute a P2MP path that is re-merge free. In some deployments, it may also be requires to signal P2MP LSPs that are both remerge and crossover free [RFC4875]. This requirement becomes more acute to address when P2MP LSP spans multiple domains. For the purposes of this document, a domain is considered to be any collection of network elements within a common sphere of address management or path computational responsibility. Examples of such domains include Interior Gateway Protocol (IGP) areas and Autonomous Systems (ASes). This is because in an inter-domain environment, the ingress node may not have topological visibility into other domains to be able to compute and signal a re-merge free P2MP LSP. In an inter-domain environment, signaling for a given (Source-to-Leaf) S2L or a set of S2Ls may contain MPLS Traffic Engineering loosely routed explicit LSPs. A loosely routed explicit LSP path is a path specified as a combination of strict and loose hop(s) that contains at least one loose hop and zero or more strict hop(s). When a border node is presented with a loose ERO (for a given S2L or a subset of S2Ls), it may not have full visibility on the P2MP LSP destinations to be able to expend the ERO such that overall P2MP LSP is remerge free. The issue becomes even more acute when one path message per S2L is used. The document propose a simple extension to allow border nodes with just enough information about the P2MP LSP so that they can expand EROs for individual S2Ls such that overall P2MP LSP is remerge free. Specifically, this document proposes a notion of passing a list of addresses to a border node, for all S2Ls of a P2MP LSP that transits from that border node. This list of addresses contains addresses for which the given border node needs to expend the EROs to, for all S2L of the P2MP LSP that transit through the border router. Alternatively, if aggregated signaling is used, path messages for all S2Ls that transit Expires May 2009 [Page 3] Internet-Draft draft-ali-mpls-inter-domain-p2mp-rsvp-te-lsp-01.txt through a given domain can be aggregated into a single Path message using signaling option specified in [RFC4875]. In either case, the idea is provide a border node with the knowledge of other IP addresses w.r.t. which the route has to be re-merge free. This enables the border node to expend route for a given P2MP LSP in a re-merge free manner. This also allows a border node to find an overall better P2MP path for the LSP. Need for finding an end-to-end path that is remerge free also increases chances for crankbacks during setting up a P2MP LSP from their P2P counterpart. Nonetheless, crankback mechanisms for P2MP LSP are not addressed by [RFC4875]. The document also describes how crankback signaling extensions for MPLS and GMPLS RSVP-TE defined in [RFC4920] applies to setting up P2MP TE LSPs. The solution also does not guarantee optimization of the overall P2MP tree. PCE can be used, instead, to address optimization of the overall P2MP tree [PCE-P2MP-BRPC]. 2. Framework TBA 3. RSVP-TE signaling extensions This section describes the signaling extensions required to address the above-mentioned functionality. 3.1. Multiple S2L Sub-LSPs in One Path Message When multiple S2Ls are carried in the single Path messages it is RECOMMENDED that P2MP LSP is partitioned in such a way that the Path message to a border node, where ERO expansion is desired, contains all S2Ls of the P2MP LSP that transit through that border router. This enabled border node to get the information about all nodes this border node needs to expend EROs to. Hence, the border node to expend all routes in a re-merged free and a more cost effective manner without any protocol expansion. When multiple S2Ls are carried in the single Path messages but the above mentioned criteria cannot be or is not satisfied, is to be addressed in a later version of the document. 3.2. Single S2L Sub-LSPs in One Path Message When a Path message contains only one S2L sub-LSP, the following extension MAY be followed to achieve ERO expansion in a remerge free and a more cost effective manner. As specified in [RFC3209], Expires May 2009 [Page 4] Internet-Draft draft-ali-mpls-inter-domain-p2mp-rsvp-te-lsp-01.txt loose hops are listed in the ERO object of the RSVP Path message with the L flag of the IPv4 or the IPv6 prefix sub-object set. When ERO in the Path message of a P2MP LSP contains a loose hop, the Path message MAY (optionally) contain a "Related Addresses for Sibling S2L sub-LSP" object for each loose hop specified in the ERO. Class = TBA, C_Type = TBA 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 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 address of the border node | | IPv4 address from related sibling S2L sub-LSP 1 | | IPv4 address from related sibling S2L sub-LSP 2 | | IPv4 address from related sibling S2L sub-LSP 1 | // // | IPv4 address from related sibling S2L sub-LSP last | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 0x01 IPv4 address Length The Length contains the total length of the object in bytes, including the Type and Length fields. The Length is variable depending on the addresses in the list. IPv4 address of the border node IPv4 address of the target border node, where ERO extension for this and related S2L sub-LSPs of the P2MP LSP is desired. This address MUST match with on of the IPv4 addresses contained in the ERO with L flag. IPv4 address from related sibling S2L sub-LSP x IPv4 address of a node on another sibling S2L sub-LSP x, which is signaled in a separate Path message but which also require ERO extension at the border node contained in IPv4 address of the border node field. Together this list contains all addresses on a given P2MP LSP to which the border node needs to expend the EROs. Expires May 2009 [Page 5] Internet-Draft draft-ali-mpls-inter-domain-p2mp-rsvp-te-lsp-01.txt 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 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address of the border node | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address from related sibling S2L sub-LSP 1 | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address from related sibling S2L sub-LSP 2 | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 address from related sibling S2L sub-LSP 1 | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ // // | IPv6 address from related sibling S2L sub-LSP last | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 0x02 IPv6 address Length The Length contains the total length of the object in bytes, including the Type and Length fields. The Length is variable depending on the addresses in the list. Expires May 2009 [Page 6] Internet-Draft draft-ali-mpls-inter-domain-p2mp-rsvp-te-lsp-01.txt IPv6 address of the border node IPv6 address of the target border node, where ERO extension for this and related S2L sub-LSPs of the P2MP LSP is desired. This address MUST match with on of the IPv6 addresses contained in the ERO with L flag. IPv6 address from related sibling S2L sub-LSP x IPv6 address of a node on another sibling S2L sub-LSP x, which is signaled in a separate Path message but which also require ERO extension at the border node contained in IPv6 address of the border node field. Together this list contains all addresses on a given P2MP LSP to which the border node needs to expend the EROs. 3.3. Grafting Grafting for an S2L sub-LSP achieved by the Ingress node signaling it with the same P2MP ID and LSP ID, via existing or new border nodes with loose hop expansion. If an existing border node is used along the path, the border node locally finds how ERO expansions for other siblings of the P2MP LSP transiting through this border node is done and expends the route of new S2L such that it's remerge free. 3.4. Crankback and Path Error If a (border) node is unable to find a route that can supply the required resources or is not remerge free, it can generate crankback or Path Error for a subset of S2L it's not able to expend the Path. For this purpose the (border) node SHOULD try to find a minimum subset of S2L for which crankback or Path Error needs to be generated. This rule applies equally to the case where Multiple S2L Sub-LSPs are signaled using one Path message, as well as to the case where a single S2L Sub-LSPs is signaled using one Path message. More details on crankback signaling extensions for P2MP-TE LSP are to be added in a later version. 4. Security Considerations Security considerations and requirements from [RFC3209] and [RFC4875] apply equally to this document. Furthermore, there are some additional security considerations that may be induced by the use of "Related Addresses for Sibling S2L sub-LSP" object defined in this document. These security considerations will be added in a later version of the draft. Expires May 2009 [Page 7] Internet-Draft draft-ali-mpls-inter-domain-p2mp-rsvp-te-lsp-01.txt 5. IANA Considerations Code points for "Related Addresses for Sibling S2L sub-LSP" object defined in this document will be required. Much of the details here are TBA. 6. References 6.1. Normative References [RFC4875] R. Aggarwal, D. Papadimitriou, S. Yasukawa, et al, "Extensions to RSVP-TE for Point-to-Multipoint TE LSPs", RFC4875. [RFC4920] A. Farrel, et al, "Crankback Signaling Extensions for MPLS and GMPLS RSVP-TE", RFC4920. 6.2. Informative References [RFC4726] A. Farrel, J.-P. Vasseur, A. Ayyangar, "A Framework for Inter-Domain Multiprotocol Label Switching Traffic Engineering", RFC 4726, November 2006. [RFC3209] D. Awduche, L. Berger, D. Gan, T. Li, V. Srinivasan, and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [PCE-P2MP-BRPC] Z. Ali, et al, "BRPC extensions for computation of Point-to-Multipoint Traffic Engineering Label Switched Paths", draft-ali-pce-brpc-p2mp-extension, work in progress. Author's Addresses Zafar Ali Cisco Systems, Inc. Email: zali@cisco.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Expires May 2009 [Page 8] Internet-Draft draft-ali-mpls-inter-domain-p2mp-rsvp-te-lsp-01.txt Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Expires May 2009 [Page 9]