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