Internet Engineering Task Force H. Chen Internet-Draft Huawei Technologies Intended status: Standards Track N. So Expires: May 2, 2012 Verizon Inc. A. Liu Ericsson October 30, 2011 Extensions to RSVP-TE for P2MP LSP Egress Local Protection draft-chen-mpls-p2mp-egress-protection-04.txt Abstract This document describes extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for locally protecting egress nodes of a Traffic Engineered (TE) point-to-multipoint (P2MP) Label Switched Path (LSP) in a Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) network. Status of this Memo This Internet-Draft is submitted to IETF 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 2, 2012. Copyright Notice Copyright (c) 2011 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 Chen, et al. Expires May 2, 2012 [Page 1] Internet-Draft P2MP LSP Egress Protection October 2011 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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Conventions Used in This Document . . . . . . . . . . . . . . 3 4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4.1. An Example of Egress Local Protection . . . . . . . . . . 4 4.2. Set up of Backup sub LSP . . . . . . . . . . . . . . . . . 5 4.3. Forwarding State for Backup sub LSP(s) . . . . . . . . . . 5 4.4. Detection of Egress Node Failure . . . . . . . . . . . . . 6 5. Egress Local Protection with FRR . . . . . . . . . . . . . . . 6 6. Representation of a Backup Sub LSP . . . . . . . . . . . . . . 7 6.1. EGRESS_BACKUP_SUB_LSP Object . . . . . . . . . . . . . . . 7 6.1.1. EGRESS_BACKUP_SUB_LSP IPv4 Object . . . . . . . . . . 7 6.1.2. EGRESS_BACKUP_SUB_LSP IPv6 Object . . . . . . . . . . 8 6.2. EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object . . . . . . 9 7. Path Message . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1. Format of Path Message . . . . . . . . . . . . . . . . . . 9 7.2. Processing of Path Message . . . . . . . . . . . . . . . . 10 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 10.1. Normative References . . . . . . . . . . . . . . . . . . . 11 10.2. Informative References . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Chen, et al. Expires May 2, 2012 [Page 2] Internet-Draft P2MP LSP Egress Protection October 2011 1. Introduction RFC 4090 "Fast Reroute Extensions to RSVP-TE for LSP Tunnels" describes two methods for protecting P2P LSP tunnels or paths at local repair points. For a P2P LSP, the local repair points are the intermediate nodes between the ingress node and the egress node of the LSP. The first method is a one-to-one protection method, where a detour backup P2P LSP for each protected P2P LSP is created at each potential point of local repair. The second method is a facility bypass backup protection method, where a bypass backup P2P LSP tunnel is created using MPLS label stacking to protect a potential failure point for a set of P2P LSP tunnels. The bypass backup tunnel can protect a set of P2P LSPs having similar backup constraints. RFC 4875 "Extensions to RSVP-TE for P2MP TE LSPs" describes how to use the one-to-one protection method and facility bypass backup protection method to protect a link or intermediate node failure on the path of a P2MP LSP. However, there is no mention of locally protecting any egress node failure in a protected P2MP LSP. This document defines extensions to RSVP-TE for locally protecting an egress node of a Traffic Engineered (TE) point-to-multipoint (P2MP) Label Switched Path through using a backup P2MP sub LSP. The same extensions and mechanism can also be used to protect the egress node of a RSVP-TE P2P LSP. 2. Terminology This document uses terminologies defined in RFC 2205, RFC 3031, RFC 3209, RFC 3473, RFC 4090, RFC 4461, and RFC 4875. 3. Conventions Used in This Document 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. 4. Mechanism This section briefly describes a solution that locally protects an egress node of a P2MP LSP through using a backup P2MP sub LSP. We first show an example, and then present different parts of the solution, which includes the creation of the backup sub LSP, the forwarding state for the backup sub LSP, and the detection of a failure in the egress node. Chen, et al. Expires May 2, 2012 [Page 3] Internet-Draft P2MP LSP Egress Protection October 2011 4.1. An Example of Egress Local Protection Figure 1 below illustrates an example of using backup sub LSPs to locally protect egress nodes of a P2MP LSP. The P2MP LSP is from ingress node R1 to three egress nodes: L1, L2 and L3. It is represented by double lines in the figure. La, Lb and Lc are the designated backup egress nodes for the egress nodes L1, L2 and L3 of the P2MP LSP respectively. In order to distinguish an egress node (e.g., L1 in the figure) and a backup egress node (e.g., La in the figure), an egress node is called a primary egress node in the follwing description. The backup sub LSP used to protect the primary egress node L1 is from its previous hop node R3 to the backup egress node La. The backup sub LSP used to protect the primary egress node L2 is from its previous hop node R5 to the backup egress node Lb. The backup sub LSP used to protect the primary egress node L3 is from its previous hop node R5 to the backup egress node Lc via the intermediate node Rc. During normal operation, the traffic transported by the P2MP LSP is forwarded through R3 to L1, then delivered to its destination CE1. When the failure of L1 is detected, R3 forwards the traffic to the backup egress node La, which then delivers the traffic to its destination CE1. L1's failure CAN be detected by a BFD session between L1 and R3. Chen, et al. Expires May 2, 2012 [Page 4] Internet-Draft P2MP LSP Egress Protection October 2011 [R2]=====[R3]=====[L1]----[CE1] // \ / // \ / // \___[La]_/ // // // // +---[R1]====[R4]====[R5]=====[L2]----[CE2] | |\\ \ / | | \\ \ / [S]--| | \\ \__[Lb]_/ | | \\ | | \\ | \\ | \\ | \\ | [L3]----[CE3] | / | / [Rc]_______[Lc]_/ Figure 1: P2MP sub LSP for Locally Protecting Egress 4.2. Set up of Backup sub LSP A backup egress node is designated for a primary egress node of a LSP. The previous hop node of the primary egress node sets up a backup sub LSP from itself to the backup egress node after receiving the information about the backup egress node. The previous hop node sets up the backup sub LSP, creates and maintains its state in the same way as of setting up a source to leaf (S2L) sub LSP from the signalling's point of view. It constructs and sends a RSVP-TE PATH message along the path for the backup sub LSP, receives and processes a RSVP-TE RESV message that responses to the PATH message. 4.3. Forwarding State for Backup sub LSP(s) The forwarding state for the backup sub LSP is different from that for a P2MP S2L sub LSP. After receiving the RSVP-TE RESV message for the backup sub LSP, the previous hop node creates a forwarding entry with an inactive state or flag called inactive forwarding entry. This inactive forwarding entry is not used to forward any data traffic during normal operations. It SHALL only be used after the failure of the primary egress node. Chen, et al. Expires May 2, 2012 [Page 5] Internet-Draft P2MP LSP Egress Protection October 2011 Upon detection of the primary egress node failure, the state or flag of the forwarding entry for the backup sub LSP is set to be active. Thus, the previous hop node of the primary egress node will forward the traffic to the backup egress node through the backup sub LSP, which then send the traffic to its destination. 4.4. Detection of Egress Node Failure The previous hop node of the primary egress node SHALL detect four types of failures described below: o The failure of the primary egress node (e.g. L1 in Figure 1) o The failure of the link between the primary egress node and its previous hop node (e.g. the link between R3 and L1 in Figure 1) o The failure of the destination node for the primary egress node (e.g. CE1 in Figure 1) o The failure of the link between the primary egress node and its destination node (e.g. the failure of the link between L1 and CE1 in Figure 1). Failure of the primary egress node and the link between itself and its previous hop node CAN be detected through a BFD session between itself and its previous hop node. Failure of the destination node and the link between the primary egress node and the destination node CAN be detected by a BFD session between the previous hop node and the destination node. Upon detecting any above mentioned failures, the previous hop node imports the traffic from the LSP into the backup sub LSP. The traffic is then delivered to its destination through the backup egress node. 5. Egress Local Protection with FRR RFC4875 "Extensions to RSVP-TE for P2MP TE LSPs" describes how to use the existing FRR to locally protect failures in a link or intermediate node of a P2MP LSP. Thus, all the links, the egress nodes and the intermediate nodes of a P2MP LSP can be locally protected through using the egress local protection mechanism described above and the FRR. All the egress nodes of the P2MP LSP can be locally protected through using the egress local protection. All the links and the Chen, et al. Expires May 2, 2012 [Page 6] Internet-Draft P2MP LSP Egress Protection October 2011 intermediate nodes of the LSP can be locally protected by using the FRR. All the intermediate nodes of the P2MP LSP may be locally protected by some other methods such as the method proposed in "P2MP MPLS-TE Fast Reroute with P2MP Bypass Tunnels". Note that the methods for locally protecting all the links and the intermediate nodes of a P2MP LSP are out of scope of this document. 6. Representation of a Backup Sub LSP A backup sub LSP exists within the context of a P2MP LSP in a way similar to a S2L sub LSP. It is identified by the P2MP LSP ID, Tunnel ID, and Extended Tunnel ID in the SESSION object, the tunnel sender address and LSP ID in the SENDER_TEMPLATE object, and the backup sub LSP destination address in the EGRESS_BACKUP_SUB_LSP object (to be defined in the section below). An EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object (EB-SERO) is used to optionally specify the explicit route of a backup sub LSP that is from a previous hop node to a backup egress node. The EB-SERO is defined in the following section. 6.1. EGRESS_BACKUP_SUB_LSP Object An EGRESS_BACKUP_SUB_LSP object identifies a particular backup sub LSP belonging to the LSP. 6.1.1. EGRESS_BACKUP_SUB_LSP IPv4 Object The class of the EGRESS_BACKUP_SUB_LSP IPv4 object is the same as that of the S2L_SUB_LSP IPv4 object defined in RFC 4875. The C-Type of the object is a new number 3, or may be another number assigned by Internet Assigned Numbers Authority (IANA). Chen, et al. Expires May 2, 2012 [Page 7] Internet-Draft P2MP LSP Egress Protection October 2011 EGRESS_BACKUP_SUB_LSP Class = 50, EGRESS_BACKUP_SUB_LSP_IPv4 C-Type = 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress Backup Sub LSP IPv4 destination address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress IPv4 address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Egress Backup Sub LSP IPv4 destination address IPv4 address of the backup sub LSP destination is the backup egress node. Egress IPv4 address IPv4 address of the egress node 6.1.2. EGRESS_BACKUP_SUB_LSP IPv6 Object The class of the EGRESS_BACKUP_SUB_LSP IPv6 object is the same as that of the S2L_SUB_LSP IPv6 object defined in RFC 4875. The C-Type of the object is a new number 4, or may be another number assigned by Internet Assigned Numbers Authority (IANA). EGRESS_BACKUP_SUB_LSP Class = 50, EGRESS_BACKUP_SUB_LSP_IPv6 C-Type = 4 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress Backup Sub LSP IPv6 destination address | | (16 bytes) | | .... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress IPv6 address | | (16 bytes) | | .... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Egress Backup Sub LSP IPv6 destination address IPv6 address of the backup sub LSP destination is the backup egress node. Egress IPv6 address IPv6 address of the egress node Chen, et al. Expires May 2, 2012 [Page 8] Internet-Draft P2MP LSP Egress Protection October 2011 6.2. EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object The format of an EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE (EB-SERO) object is defined as identical to that of the ERO. The class of the EB-SERO is the same as that of the SERO defined in RFC 4873. The EB- SERO uses a new C-Type 3, or may use another number assigned by Internet Assigned Numbers Authority (IANA). The formats of sub- objects in an EB-SERO are identical to those of sub-objects in an ERO defined in RFC 3209. 7. Path Message This section describes extensions to the Path message defined in RFC 4875. The Path message is enhanced to transport the information about a backup egress node to the previous hop node of a primary egress node of a P2MP LSP through including an egress backup sub LSP descriptor list. 7.1. Format of Path Message The format of the enhanced Path message is illustrated below. ::= [ ] [ [ | ] ...] [ ] [ ] [ ] [ ... ] [ ] [ ] [ ] [ ... ] [] [] The format of the egress backup sub LSP descriptor list in the enhanced Path message is defined as follows. Chen, et al. Expires May 2, 2012 [Page 9] Internet-Draft P2MP LSP Egress Protection October 2011 ::= [ ] ::= [ ] 7.2. Processing of Path Message The ingress node of a LSP initiates a Path message with an egress backup sub LSP descriptor list for protecting primary egress nodes of the LSP. In order to protect a primary egress node of the LSP, the ingress node MUST add an EGRESS_BACKUP_SUB_LSP object into the list. The object contains the information about the backup egress node to be used to protect the failure of the primary egress node. An EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE object (EB-SERO), which describes an explicit path to the backup egress node, SHALL follow the EGRESS_BACKUP_SUB_LSP. If the previous hop node of the primary egress node receives the Path message with an egress backup sub LSP descriptor list, it generates a new Path message based on the information in the EGRESS_BACKUP_SUB_LSP (and according to EB-SERO if it exists) containing the backup egress node. The format of this new Path message is the same as that of the Path message defined in RFC 4875. This new Path message is used to signal the segment of a special S2L sub-LSP from the previous hop node to the backup egress node. The new Path message is sent to the next-hop node along the path for the backup sub LSP. If an intermediate node receives the Path message with an egress backup sub LSP descriptor list. Then it MUST put the EGRESS_BACKUP_SUB_LSP (according to EB-SERO if exists) containing a backup egress into a Path message to be sent towards the backup egress. This SHALL be done for each EGRESS_BACKUP_SUB_LSP containing a backup egress node in the list. When a primary egress node of the LSP receives the Path message with an egress backup sub LSP descriptor list, it SHOULD ignore the egress backup sub LSP descriptor list and generate a PathErr message. 8. IANA Considerations TBD Chen, et al. Expires May 2, 2012 [Page 10] Internet-Draft P2MP LSP Egress Protection October 2011 9. Acknowledgement The authors would like to thank Richard Li, Neil Harrison, Lei Liu, Kannan Sampath, Yimin Shen and Quintin Zhao for their valuable comments and suggestions on this draft. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers Considered Useful", BCP 82, RFC 3692, January 2004. [RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, January 2001. [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. [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, "Extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for Point-to-Multipoint TE Label Switched Paths (LSPs)", RFC 4875, May 2007. [P2MP FRR] Le Roux, J., Aggarwal, R., Vasseur, J., and M. Vigoureux, "P2MP MPLS-TE Fast Reroute with P2MP Bypass Tunnels", draft-leroux-mpls-p2mp-te-bypass , March 1997. Chen, et al. Expires May 2, 2012 [Page 11] Internet-Draft P2MP LSP Egress Protection October 2011 10.2. Informative References [RFC4461] Yasukawa, S., "Signaling Requirements for Point-to- Multipoint Traffic-Engineered MPLS Label Switched Paths (LSPs)", RFC 4461, April 2006. Authors' Addresses Huaimo Chen Huawei Technologies Boston, MA USA Email: Huaimochen@huawei.com Ning So Verizon Inc. 2400 North Glenville Drive Richardson, TX 75082 USA Email: Ning.So@verizonbusiness.com Autumn Liu Ericsson CA USA Email: autumn.liu@ericsson.com Chen, et al. Expires May 2, 2012 [Page 12]