Scalable BGP FRR Protection against Edge Node Failure
draft-bashandy-bgp-edge-node-frr-02

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Network Working Group                                       A. Bashandy
Internet Draft                                             B. Pithawala
Intended status: Standards Track                               K. Patel
Expires: September 2012                                   Cisco Systems
                                                          March 2, 2012

          Scalable BGP FRR Protection against Edge Node Failure
                 draft-bashandy-bgp-edge-node-frr-02.txt

Abstract

Consider a BGP free core scenario. Suppose the edge BGP speakers PE1,
PE2,..., PEn know about a prefix P/m via the external routers CE1,
CE2,..., CEm.  If the edge router PEi crashes or becomes totally
disconnected from the core, it is desirable for a core  router "P"
carrying traffic to the failed edge router PEi to immediately restore
traffic by re-tunneling packets originally tunneled to PEi and
destined to the prefix P/m to one of the other edge routers that
advertised P/m, say PEj, until BGP re-converges. In doing so, it is
highly desirable to keep the core BGP-free while not imposing
restrictions on external connectivity. Thus (1) a core router should
not be required to learn any BGP prefix, (2) the size of the
forwarding and routing tables in the core routers should be
independent of the number of BGP prefixes,(3) there should be no
special router (or group of routers) that handles restoring traffic
or the need for one router to store the forwarding table of another
router, (4) re-routing traffic without waiting for re-convergence
must not cause loops, and (4) there should be no restrictions on what
edge routers advertise what prefixes. For labeled prefixes, (6) the
repairing core router must swap the label stack advertised by the
failed edge router PEi for the prefix P/m with the label stack
advertised for the same prefix by the edge router PEj before re-
tunneling the packet to PEj

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Bashandy              Expires September 2, 2012                [Page 1]
Internet-Draft      BGP FRR For Edge Node Failure            March 2012

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Table of Contents

   1. Introduction...................................................3
      1.1. Conventions used in this document.........................4
      1.2. Terminology...............................................5
      1.3. Problem definition........................................6
   2. Control Plane Operation........................................7
      2.1. Step 1: Calculation of the Repair PE......................8
      2.2. Step 2: Assigning and Advertising the BGP Next-hop........8
      2.3. Step 3: Informing core routers about the repair path......9
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