Graceful Restart Mechanism for BGP with MPLS
RFC 4781
Document | Type | RFC - Proposed Standard (January 2007; No errata) | |
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Authors | Yakov Rekhter , Rahul Aggarwal | ||
Last updated | 2018-12-20 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4781 (Proposed Standard) | |
Action Holders |
(None)
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||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Alex Zinin | ||
Send notices to | (None) |
Network Working Group Y. Rekhter Request for Comments: 4781 R. Aggarwal Category: Standards Track Juniper Networks January 2007 Graceful Restart Mechanism for BGP with MPLS Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2007). Abstract A mechanism for BGP that helps minimize the negative effects on routing caused by BGP restart has already been developed and is described in a separate document ("Graceful Restart Mechanism for BGP"). This document extends this mechanism to minimize the negative effects on MPLS forwarding caused by the Label Switching Router's (LSR's) control plane restart, and specifically by the restart of its BGP component when BGP is used to carry MPLS labels and the LSR is capable of preserving the MPLS forwarding state across the restart. The mechanism described in this document is agnostic with respect to the types of the addresses carried in the BGP Network Layer Reachability Information (NLRI) field. As such, it works in conjunction with any of the address families that could be carried in BGP (e.g., IPv4, IPv6, etc.). Rekhter & Aggarwal Standards Track [Page 1] RFC 4781 Graceful Restart Mechanism for BGP January 2007 Table of Contents 1. Introduction ....................................................2 1.1. Specification of Requirements ..............................3 2. General Requirements ............................................3 3. Capability Advertisement ........................................4 4. Procedures for the Restarting LSR ...............................4 4.1. Case 1 .....................................................4 4.2. Case 2 .....................................................5 4.3. Case 3 .....................................................5 5. Alternative Procedures for the Restarting LSR ...................6 6. Procedures for a Neighbor of a Restarting LSR ...................6 7. Comparison between Alternative Procedures for the Restarting LSR ..................................................7 8. Security Considerations .........................................8 9. Acknowledgments .................................................9 10. References .....................................................9 10.1. Normative References ......................................9 10.2. Informative References ....................................9 1. Introduction In the case where a Label Switching Router (LSR) could preserve its MPLS forwarding state across restart of its control plane, and specifically its BGP component, and BGP is used to carry MPLS labels (e.g., as specified in [RFC3107]), it may be desirable not to perturb the LSPs going through that LSR (and specifically, the LSPs established by BGP) after failure or restart of the BGP component of the control plane. In this document, we describe a mechanism that allows this goal to be accomplished. The mechanism described in this document works in conjunction with the mechanism specified in [RFC4724]. The mechanism described in this document places no restrictions on the types of addresses (address families) that it can support. The mechanism described in this document is applicable to all LSRs, both those with the ability to preserve forwarding state during BGP restart and those without it (although the latter need to implement only a subset of this mechanism). Supporting a subset of the mechanism described here by the LSRs that cannot preserve their MPLS forwarding state across the restart would not reduce the negative impact on MPLS traffic caused by their control plane restart. However, the impact would be minimized if their neighbor(s) are capable of preserving the forwarding state across the restart of their control plane, and if they implement the mechanism described here. The subset includes all the procedures described in this document, except the procedures in Sections 4.1, 4.2, 4.3, and 5. Rekhter & Aggarwal Standards Track [Page 2] RFC 4781 Graceful Restart Mechanism for BGP January 2007 For the sake of brevity, by "MPLS forwarding state" we mean one of the following mappings: <incoming label -> (outgoing label, next hop)>Show full document text