Path Segment in MPLS Based Segment Routing Network
draft-ietf-spring-mpls-path-segment-01

Document Type Active Internet-Draft (spring WG)
Last updated 2019-09-16
Replaces draft-cheng-spring-mpls-path-segment
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Network Working Group                                           W. Cheng
Internet-Draft                                                     H. Li
Intended status: Standards Track                            China Mobile
Expires: March 19, 2020                                          M. Chen
                                                                  Huawei
                                                               R. Gandhi
                                                     Cisco Systems, Inc.
                                                               R. Zigler
                                                                Broadcom
                                                      September 16, 2019

           Path Segment in MPLS Based Segment Routing Network
                 draft-ietf-spring-mpls-path-segment-01

Abstract

   A Segment Routing (SR) path is identified by an SR segment list.
   Only the full segment list identifies the full end-to-end path, and
   one segment or a partial set of segments from the list cannot
   identify the SR path and distinguish it from other SR paths that may
   be partially congruent.  But path identification is a pre-requisite
   for various use-cases such as performance measurement (PM) of an SR
   path.

   In SR for MPLS (SR-MPLS) the segment identifiers are stripped from
   the packet through label popping as the packet transits the network.
   This means that when a packet reaches the egress of the SR path, it
   is not possible to determine on which SR path it traversed the
   network.

   This document defines a new type of segment that is referred to as
   Path Segment, which is used to identify an SR path in an SR-MPLS
   network.  When used, it is inserted at the ingress node of the SR
   path and immediately follows the last segment identifier in the
   segment list of the SR path.  The Path Segment will not be popped off
   until it reaches the egress node of the SR path.

   A Path Segment can be used by the egress node to implement path
   identification hence to support various use-cases including SR path
   PM, end-to-end 1+1 SR path protection, and bidirectional SR paths
   correlation.

Status of This Memo

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

Cheng, et al.            Expires March 19, 2020                 [Page 1]
Internet-Draft           Path Segment in SR-MPLS          September 2019

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Copyright Notice

   Copyright (c) 2019 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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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Path Segment  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Nesting of Path Segments  . . . . . . . . . . . . . . . . . .   5
   4.  Path Segment Allocation . . . . . . . . . . . . . . . . . . .   6
   5.  Path Segment for PM . . . . . . . . . . . . . . . . . . . . .   7
   6.  Path Segment for Bi-directional SR Path . . . . . . . . . . .   7
   7.  Path Segment for End-to-end Path Protection . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     12.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     12.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10
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