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Path Segment in MPLS Based Segment Routing Network

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft whose latest revision state is "Active".
Expired & archived
Authors Weiqiang Cheng , Han Li , Mach Chen , Rakesh Gandhi , Royi Zigler
Last updated 2020-08-29 (Latest revision 2020-02-26)
Replaces draft-cheng-spring-mpls-path-segment
RFC stream Internet Engineering Task Force (IETF)
SECDIR Last Call Review Incomplete, due 2022-11-20
OPSDIR Last Call Review Incomplete, due 2022-11-20
Additional resources Mailing list discussion
Stream WG state WG Document
Document shepherd (None)
IESG IESG state Expired
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


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.


Weiqiang Cheng
Han Li
Mach Chen
Rakesh Gandhi
Royi Zigler

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)