Node Protection for SR-TE Paths
draft-hegde-spring-node-protection-for-sr-te-paths-07
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2020-07-30
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Routing area S. Hegde
Internet-Draft C. Bowers
Intended status: Informational Juniper Networks Inc.
Expires: January 31, 2021 S. Litkowski
Cisco Systems
X. Xu
Alibaba Inc.
F. Xu
Tencent
July 30, 2020
Node Protection for SR-TE Paths
draft-hegde-spring-node-protection-for-sr-te-paths-07
Abstract
Segment routing supports the creation of explicit paths using
adjacency-sids, node-sids, and binding-sids. It is important to
provide fast reroute (FRR) mechanisms to respond to failures of links
and nodes in the Segment-Routed Traffic-Engineered(SR-TE) path. A
point of local repair (PLR) can provide FRR protection against the
failure of a link in an SR-TE path by examining only the first (top)
label in the SR label stack. In order to protect against the failure
of a node, a PLR may need to examine the second label in the stack as
well, in order to determine SR-TE path beyond the failed node. This
document specifies how a PLR can use the first and second label in
the label stack describing an SR-TE path to provide protection
against node failures.
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-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 31, 2021.
Hegde, et al. Expires January 31, 2021 [Page 1]
Internet-Draft Node Protection for SR-TE Paths July 2020
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Node Failures Along SR-TE Paths . . . . . . . . . . . . . . . 3
2.1. Node protection for node-sid explicit paths . . . . . . . 3
2.2. Node-Protection for Anycast-SIDs . . . . . . . . . . . . 4
2.3. Node-protection for adj-sid explicit paths . . . . . . . 5
3. Detailed Solution using Context Tables . . . . . . . . . . . 6
3.1. Building Context Tables . . . . . . . . . . . . . . . . . 6
3.2. Node protection for node SIDs . . . . . . . . . . . . . . 7
3.3. Node protection for adjacency SIDs . . . . . . . . . . . 8
3.4. Node protection for edge nodes . . . . . . . . . . . . . 9
4. Hold timers for Node-SID/Prefix-SIDs and Adjacency-SIDs . . . 10
4.1. Interaction with micro-loop avoidance . . . . . . . . . . 10
5. Optimization Considerations . . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
It is possible for a routing device to completely go out of service
abruptly due to power failure, hardware failure or software crashes.
Node protection is an important property of the Fast Reroute
mechanism. It provides protection against a node failure by
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