Topology Independent Fast Reroute using Segment Routing
draft-francois-rtgwg-segment-routing-ti-lfa-01

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Replaced by draft-bashandy-rtgwg-segment-routing-ti-lfa
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Network Working Group                                    Pierre Francois
Internet-Draft                                         Clarence Filsfils
Intended status: Standards Track                          Ahmed Bashandy
Expires: November 18, 2016                           Cisco Systems, Inc.
                                                          Bruno Decraene
                                                      Stephane Litkowski
                                                                  Orange
                                                            May 17, 2016

        Topology Independent Fast Reroute using Segment Routing
             draft-francois-rtgwg-segment-routing-ti-lfa-01

Abstract

   This document presents Topology Independent Loop-free Alternate Fast
   Re-route (TI-LFA), aimed at providing protection of node and
   adjacency segments within the Segment Routing (SR) framework.  This
   Fast Re-route (FRR) behavior builds on proven IP-FRR concepts being
   LFAs, remote LFAs (RLFA), and remote LFAs with directed forwarding
   (DLFA).  It extends these concepts to provide guaranteed coverage in
   any IGP network.  A key aspect of TI-LFA is the FRR path selection
   approach establising protection over post-convergence paths from the
   point of local repair, dramatically reducing the operational need to
   control the tie-breaks among various FRR options.

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Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Pierre Francois, et al.  Expires November 18, 2016              [Page 1]
Internet-Draft                  SR TI-LFA                       May 2016

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Intersecting P-Space and Q-Space with post-convergence
       paths  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  P-Space property computation for a resource X  . . . . . .  5
     3.2.  Q-Space property computation for a link S-F, over
           post-convergence paths . . . . . . . . . . . . . . . . . .  6
     3.3.  Q-Space property computation for a set of links
           adjacent to S, over post-convergence paths . . . . . . . .  6
     3.4.  Q-Space property computation for a node F, over
           post-convergence paths . . . . . . . . . . . . . . . . . .  6
   4.  TI-LFA Repair Tunnel . . . . . . . . . . . . . . . . . . . . .  6
     4.1.  The repair node is a direct neighbor . . . . . . . . . . .  7
     4.2.  The repair node is a PQ node . . . . . . . . . . . . . . .  7
     4.3.  The repair is a Q node, neighbor of the last P node  . . .  7
     4.4.  Connecting distant P and Q nodes along
           post-convergence paths . . . . . . . . . . . . . . . . . .  7
   5.  Protecting segments  . . . . . . . . . . . . . . . . . . . . .  7
     5.1.  The active segment is a node segment . . . . . . . . . . .  7
     5.2.  The active segment is an adjacency segment . . . . . . . .  8
       5.2.1.  Protecting [Adjacency, Adjacency] segment lists  . . .  8
       5.2.2.  Protecting [Adjacency, Node] segment lists . . . . . .  8
     5.3.  Protecting SR policy midpoints against node failure  . . .  9
       5.3.1.  Protecting {F, T, D} or {S->F, T, D} . . . . . . . . .  9
       5.3.2.  Protecting {F, F->T, D} or {S->F, F->T, D} . . . . . .  9
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10

Pierre Francois, et al.  Expires November 18, 2016              [Page 2]
Internet-Draft                  SR TI-LFA                       May 2016
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