Networking Working Group A. Jiang, Ed. K. Hu J. Luo Internet Draft ZTE Intended status: Standard Track June 22, 2009 Expires: Nov 22, 2009 LDP Graceful Restart for Pseudowire draft-jiang-pwe3-ldp-gr-00.txt 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), 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 Nov 22, 2009. Abstract This document describes a LDP graceful restart(GR) mechanism that helps to minimize the negative effects on single or multi-segment pseudowire traffic caused by Provider Edge (PE) control plane restart, specifically by the restart of its Label Distribution Protocol (LDP) component. Jiang Expires Nov 22, 2009 [Page 1] Internet-Draft PW LDP GR June 2009 Table of Contents 1. Introduction................................................2 2. Conventions used in this document...........................3 3. Single-segment Pseudowire LDP Graceful Restart Mechanism....3 4. Multi-segment Pseudowire LDP Graceful Restart Mechanism.....3 5. Virtual Private LAN Service LDP Graceful Restart Mechanism..3 6. Security Considerations.....................................4 7. IANA Considerations.........................................4 8. Conclusions.................................................4 9. References..................................................4 9.1. Normative References...................................4 9.2. Informative References.................................5 10. Acknowledgments............................................5 1. Introduction Single-segment pseudowire defined in [RFC 3985] allows multi services to be carried over packet switching networks. [RFC 4447] defines extension to LDP for single-segment pseudowire setup and maintenance. The extended LDP is called Targeted LDP and runs between the end points. As defined in [RFC 5254], multi-segment pseudowire allows pseudowire traffic to transport over multiple PSN administrative or technological domains. And it also states three setup mechanisms of static configuration, signaled with pre-determined route and signaled with dynamic route. [DYNAMIC MS-PW] defines extension to LDP for multi-segment pseudowire setup using generalized FEC 129 which needs the relay of LDP signaling cross each pseudowire segment. [RFC 3478] defines graceful restart mechanism for LDP, in which LSRs are enhanced with the ability to preserve MPLS forwarding state during LDP restart. The mechanism defined in [RFC 3478] is for MPLS LSP and can be applied to pseudowire. The purpose of this draft is to specify the procedures and possible extensions to LDP for single-segment and multi-segment pseudowire control plane graceful restart. Jiang Expires December 22, 2009 [Page 2] Internet-Draft PW LDP GR June 2009 2. 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]. 3. Single-segment Pseudowire LDP Graceful Restart Mechanism LDP graceful restart procedure for single-segment pseudowire follows the same mechanism described in LDP graceful restart for MPLS [RFC 3478]. The difference is that in pseudowire scenario, the preserved labels are pseudowire labels, while in the case of MPLS, the reserved labels are for MPLS LSPs. Also, pseudowire status is UP and forwarding state is preserved during the LDP graceful restart. While upon graceful restart failure, pseudowire will be torn down. Pseudowire can be set up again later. It should be noticed that pseudowire LDP graceful restart capability is decoupled from MPLS LSP LDP graceful restart capability, because the outer layer tunnel for pseudowire could be other than MPLS LSP. 4. Multi-segment Pseudowire LDP Graceful Restart Mechanism Multi-segment pseudowire is segmented into a number of single segment pseudowires. Each single segment pseudowire can have its own LDP graceful restart procedure, which can be independent from each other. For each affected segment, the procedure is very similar to that of single-segment pseudowire LDP graceful restart, while it has extra steps for failure handling. When LDP graceful restart failed, PEs in relevant segment will send PW label withdraw message to their upstream peers and PW label release message to their downstream peers so as to tear down the multi-segment pseudowire. After that, MS-PW could be re-established. 5. Virtual Private LAN Service LDP Graceful Restart Mechanism As defined in [RFC 4762], full mesh LDP sessions are established among all PEs for VPLS PWs. LDP graceful restart for VPLS follows the same mechanism as defined in LDP graceful restart for SS-PW. In H-VPLS model defined in [RFC 4762], spoke links between MTU and hub PE may span multiple administrative domain in which case LDP graceful restart procedure for MS-PW may be used. Jiang Expires December 22, 2009 [Page 3] Internet-Draft PW LDP GR June 2009 6. Security Considerations [RFC5036] describes the security considerations that apply to the base LDP specification. The same security framework and considerations apply to the capability mechanism described in this document. 7. IANA Considerations None. 8. Conclusions In this document, LDP graceful restart mechanism for MPLS LSP defined in [RFC 3478] is extended to cover pseudowire, and scenarios of SS-PW,MS-PW,VPLS and H-VPLS are discussed. In next version, solution will be developed for P2MP pseudowire. 9. References 9.1. Normative References [RFC 5036] Andersson, L., Menei, I., and Thomas, B., Editors, "LDP Specification", RFC 5036, September 2007. [RFC 3478] Leelanivas, M., Aggarwal R., Editors, "Graceful Restart Mechanism for Label Distribution Protocol", RFC 3478, February 2003. [RFC 3479] Farrel, A., "Fault Tolerance for the Label Distribution Protocol (LDP)", RFC 3479, February 2003. [RFC 4447] Martini, L., Rosen, E., El-Aawar, N., Smith, T., Heron, G., Editors, "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", RFC 4447, October 2008. [RFC 4762] Lasserre, M., Kompella, V., Editors, " Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling", RFC 4762, January 2007. [RFC 2119] Bradner, S., Editor, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC2119, March 1997. Jiang Expires December 22, 2009 [Page 4] Internet-Draft PW LDP GR June 2009 9.2. Informative References [RFC 5254] Bitar, N., Bocci M., Martini, L., Editors, "Requirements for Multi-Segment Pseudowire Emulation Edge-to-Edge (PWE3)", RFC 5254, October 2008. [MS-PW_ARCH] Bocci M., Bryant, S., Editors, "An Architecture for Multi-Segment Pseudowire Emulation Edge-to-Edge" draft- ietf-pwe3-ms-pw-arch-06.txt, Work in Progress, February 2009. [DYNAMIC MS-PW] Martini, L., Bocci M., Balus, F., Editors, "Dynamic Placement of Multi Segment Pseudo Wires" draft-ietf-pwe3- dynamic-ms-pw-09, Work in Progress, February 2009. [SEGMENTED PW] Martini, L., Metz, C., Nadeau, T., Bocci M., Balus, F., Aissaoui, M., Duckett, M., Editors, "Segmented Pseudowire" draft-ietf-pwe3-segmented-pw-11.txt, Work in Progress, February 2009. [LDP_CAPABILITY] Thomas, B., Aggarwal, S., Aggarwal, R., Le Roux, J.L., Syed Kamran Raza, Editors, "LDP Capabilities" draft- ietf-mpls-ldp-capabilities-04.txt, Work in Progress, April 2009. 10. Acknowledgments This document was prepared using 2-Word-v2.0.template.dot. Jiang Expires December 22, 2009 [Page 5] Internet-Draft PW LDP GR June 2009 Authors' Addresses Albert Jiang No.68 Zijinghua Road, Yuhuatai District Nanjing, China Phone: +86-15312021250 Email: albert.john@zte.com.cn Kan Hu No.68 Zijinghua Road, Yuhuatai District Nanjing, China Phone: +86-52870000 Email: hu.kan@zte.com.cn Jian Luo No.68 Zijinghua Road, Yuhuatai District Nanjing, China Phone: +86-52870000 Email: luo.jian@zte.com.cn Full Copyright Statement Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Jiang Expires December 22, 2009 [Page 6]