Accelerated Routing Convergence for BGP Graceful Restart
draft-ietf-idr-enhanced-gr-05

Network Working Group                                          K. Patel
Internet Draft                                                  E. Chen
Intended Status: Standards Track                            R. Fernando
Expiration Date: June 5, 2015                             Cisco Systems
                                                             J. Scudder
                                                       Juniper Networks
                                                       December 4, 2014

        Accelerated Routing Convergence for BGP Graceful Restart
                   draft-ietf-idr-enhanced-gr-05.txt

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Patel, Chen, Fernando and Scudder                               [Page 1]

Internet Draft      draft-ietf-idr-enhanced-gr-05.txt      December 2014

   described in the Simplified BSD License.

Abstract

   In this document we specify extensions to BGP graceful restart in
   order to avoid unnecessary transmission of the routing information
   preserved across a session restart, thus accelerating the routing
   convergence.

1. Introduction

   Currently the BGP graceful restart (GR) mechanism specified in
   [RFC4724] requires a complete re-advertisement of the routing
   information across a session restart, even though the routing
   information may have been preserved.  For example, as described in
   [RFC4724], the "Receiving Speaker" temporarily maintains the routes
   received from its neighbor with the GR Capability.  In addition, the
   "Restarting Speaker" may also be able to preserve routing information
   across a BGP restart by check-pointing routing information to a
   standby or secondary facility.

   Clearly the routing re-convergence post a session restart would be
   faster if we can avoid unnecessary transmission of the routing
   information preserved across a session restart. That is the goal of
   this document.

   In this document we specify extensions to BGP graceful restart in
   order to avoid unnecessary transmission of the routing information
   preserved across a session restart, thus accelerating the routing
   convergence.  More specifically, we describe a "version number" based
   mechanism for keeping track of the routing information across a
   session restart.  A new BGP message type, UPDATE-VERSION, is
   introduced for checkpointing the update version maintained for a
   neighbor.  We also introduce the Enhanced Graceful Restart
   Capability, and specify procedures for handling routing update across
   a session restart.

1.1. Specification of Requirements

   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 [RFC2119].

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Internet Draft      draft-ietf-idr-enhanced-gr-05.txt      December 2014

2. Version Numbers for Routing Entities

   In order to avoid unnecessary transmission of the routing information
   preserved across a session restart, a BGP speaker will need to
   identify exactly "what" has been preserved by a remote speaker.

   The approach described here is "version number" (or "sequence