Requirements for the Graceful Shutdown of BGP Sessions
RFC 6198

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Internet Engineering Task Force (IETF)                       B. Decraene
Request for Comments: 6198                                France Telecom
Category: Informational                                      P. Francois
ISSN: 2070-1721                                                      UCL
                                                              C. Pelsser
                                                                     IIJ
                                                                Z. Ahmad
                                                Orange Business Services
                                                  A.J. Elizondo Armengol
                                                          Telefonica I+D
                                                               T. Takeda
                                                                     NTT
                                                              April 2011

         Requirements for the Graceful Shutdown of BGP Sessions

Abstract

   The Border Gateway Protocol (BGP) is heavily used in Service Provider
   networks for both Internet and BGP/MPLS VPN services.  For resiliency
   purposes, redundant routers and BGP sessions can be deployed to
   reduce the consequences of an Autonomous System Border Router (ASBR)
   or BGP session breakdown on customers' or peers' traffic.  However,
   simply taking down or even bringing up a BGP session for maintenance
   purposes may still induce connectivity losses during the BGP
   convergence.  This is no longer satisfactory for new applications
   (e.g., voice over IP, online gaming, VPN).  Therefore, a solution is
   required for the graceful shutdown of a (set of) BGP session(s) in
   order to limit the amount of traffic loss during a planned shutdown.
   This document expresses requirements for such a solution.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6198.

Decraene, et al.              Informational                     [Page 1]
RFC 6198             Reqs for Graceful BGP Shutdown           April 2011

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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................2
   2. Conventions Used in This Document ...............................3
   3. Problem Statement ...............................................4
      3.1. Example of Undesirable BGP Routing Behavior ................4
      3.2. Causes of Packet Loss ......................................5
   4. Terminology .....................................................6
   5. Goals and Requirements ..........................................7
   6. Security Considerations ........................................10
   7. References .....................................................10
      7.1. Normative References ......................................10
      7.2. Informative References ....................................10
   Acknowledgments ...................................................11
   Appendix A. Reference BGP Topologies ..............................12
      A.1. EBGP Topologies ...........................................12
      A.2. IBGP Topologies ...........................................15
      A.3. Routing Decisions .........................................19

1.  Introduction

   The Border Gateway Protocol (BGP) [RFC4271] is heavily used in
   Service Provider networks for both Internet and BGP/MPLS VPN services
   [RFC4364].  For resiliency purposes, redundant routers and BGP
   sessions can be deployed to reduce the consequences of an Autonomous
   System Border Router (ASBR) or BGP session breakdown on customers' or
   peers' traffic.

   We place ourselves in the context where a Service Provider performs a