Path Segment in MPLS Based Segment Routing Network
draft-ietf-spring-mpls-path-segment-02

Document Type Active Internet-Draft (spring WG)
Last updated 2020-02-26
Replaces draft-cheng-spring-mpls-path-segment
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SPRING Working Group                                            W. Cheng
Internet-Draft                                                     H. Li
Intended status: Standards Track                            China Mobile
Expires: August 29, 2020                                         M. Chen
                                                                  Huawei
                                                               R. Gandhi
                                                     Cisco Systems, Inc.
                                                               R. Zigler
                                                                Broadcom
                                                       February 26, 2020

           Path Segment in MPLS Based Segment Routing Network
                 draft-ietf-spring-mpls-path-segment-02

Abstract

   A Segment Routing (SR) path is identified by an SR segment list.
   Only the complete segment list can identify the end-to-end SR path,
   and a sub-set of segments from the segment list cannot distinguish
   one SR path from another as they may be partially congruent.  SR path
   identification is a pre-requisite for various use-cases such as
   Performance Measurement (PM), bidirectional paths correlation, and
   end-to-end 1+1 path protection.

   In SR for MPLS data plane (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 by 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.  The Path Segment
   then can be used by the egress node to implement SR path
   identification and correlation.

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
   Task Force (IETF).  Note that other groups may also distribute

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Internet-Draft           Path Segment in SR-MPLS           February 2020

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   This Internet-Draft will expire on August 29, 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Path Segment  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Path Segment Allocation . . . . . . . . . . . . . . . . . . .   6
   4.  Nesting of Path Segments  . . . . . . . . . . . . . . . . . .   6
   5.  Path Segment for Performance Measurement  . . . . . . . . . .   7
   6.  Path Segment for Bidirectional SR Path  . . . . . . . . . . .   8
   7.  Path Segment for End-to-end Path Protection . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  11
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

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