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