Segment Protection for SR-TE Paths
draft-ietf-spring-segment-protection-sr-te-paths-00

Document Type Active Internet-Draft (spring WG)
Authors Shraddha Hegde  , Chris Bowers  , Stephane Litkowski  , Xiaohu Xu  , Feng Xu 
Last updated 2020-09-30
Replaces draft-ietf-spring-node-protection-for-sr-te-paths
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Routing area                                                    S. Hegde
Internet-Draft                                                 C. Bowers
Intended status: Informational                     Juniper Networks Inc.
Expires: April 3, 2021                                      S. Litkowski
                                                           Cisco Systems
                                                                   X. Xu
                                                            Alibaba Inc.
                                                                   F. Xu
                                                                 Tencent
                                                      September 30, 2020

                   Segment Protection for SR-TE Paths
          draft-ietf-spring-segment-protection-sr-te-paths-00

Abstract

   Segment routing supports the creation of explicit paths using Adj-
   Segment-ID (SID), Node-SIDs, and BSIDs.  It is important to provide
   fast reroute (FRR) mechanisms to respond to failures of links and
   nodes in the Segment-Routed Traffic-Engineered(SR-TE) path.  A point
   of local repair (PLR) can provide FRR protection against the failure
   of a link in an SR-TE path by examining only the first (top) label in
   the SR label stack.  In order to protect against the failure of a
   node, a PLR may need to examine the second label in the stack as
   well, in order to determine SR-TE path beyond the failed node.  This
   document specifies how a PLR can use the first and second label in
   the SR-MPLS label stack describing an SR-TE path to provide
   protection against node failures.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on April 3, 2021.

Hegde, et al.             Expires April 3, 2021                 [Page 1]
Internet-Draft     Segment Protection for SR-TE Paths     September 2020

Copyright Notice

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Node Failures Along SR-TE Paths . . . . . . . . . . . . . . .   3
     2.1.  Segment protection for explicit paths with Node-SIDs  . .   4
     2.2.  Segment Protection for Anycast-SIDs . . . . . . . . . . .   4
     2.3.  Segment protection for explicit paths with Adj-SIDs . . .   5
   3.  Detailed Solution using Context Tables  . . . . . . . . . . .   7
     3.1.  Building Context Tables . . . . . . . . . . . . . . . . .   7
     3.2.  Segment protection for Node-SIDs  . . . . . . . . . . . .   8
     3.3.  Segment protection for Adj-SIDs . . . . . . . . . . . . .   9
     3.4.  Segment protection for edge nodes . . . . . . . . . . . .  10
       3.4.1.  Detailed Example for Segment protection for edge
               nodes . . . . . . . . . . . . . . . . . . . . . . . .  11
   4.  Determining node can be bypassed  . . . . . . . . . . . . . .  12
   5.  Hold timers for Node-SID/Prefix-SIDs and Adj-SIDs . . . . . .  13
     5.1.  Interaction with micro-loop avoidance . . . . . . . . . .  14
   6.  Optimization Considerations . . . . . . . . . . . . . . . . .  14
     6.1.  Segment Protection Example with Common SRGB . . . . . . .  15
   7.  Operational Considerations  . . . . . . . . . . . . . . . . .  16
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  17
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  17
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     11.2.  Informative References . . . . . . . . . . . . . . . . .  17
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