Segment Protection for SR-TE Paths
draft-ietf-spring-segment-protection-sr-te-paths-00
Routing area S. Hegde
Internet-Draft C. Bowers
Intended status: Informational Juniper Networks Inc.
Expires: April 3, 2021 S. Litkowski
Cisco Systems
X. Xu
Alibaba Inc.
F. Xu
Tencent
September 30, 2020
Segment Protection for SR-TE Paths
draft-ietf-spring-segment-protection-sr-te-paths-00
Abstract
Segment routing supports the creation of explicit paths using Adj-
Segment-ID (SID), Node-SIDs, and BSIDs. 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 SR-MPLS label stack describing an SR-TE path to provide
protection against node failures.
Status of This Memo
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This Internet-Draft will expire on April 3, 2021.
Hegde, et al. Expires April 3, 2021 [Page 1]
Internet-Draft Segment Protection for SR-TE Paths September 2020
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Node Failures Along SR-TE Paths . . . . . . . . . . . . . . . 3
2.1. Segment protection for explicit paths with Node-SIDs . . 4
2.2. Segment Protection for Anycast-SIDs . . . . . . . . . . . 4
2.3. Segment protection for explicit paths with Adj-SIDs . . . 5
3. Detailed Solution using Context Tables . . . . . . . . . . . 7
3.1. Building Context Tables . . . . . . . . . . . . . . . . . 7
3.2. Segment protection for Node-SIDs . . . . . . . . . . . . 8
3.3. Segment protection for Adj-SIDs . . . . . . . . . . . . . 9
3.4. Segment protection for edge nodes . . . . . . . . . . . . 10
3.4.1. Detailed Example for Segment protection for edge
nodes . . . . . . . . . . . . . . . . . . . . . . . . 11
4. Determining node can be bypassed . . . . . . . . . . . . . . 12
5. Hold timers for Node-SID/Prefix-SIDs and Adj-SIDs . . . . . . 13
5.1. Interaction with micro-loop avoidance . . . . . . . . . . 14
6. Optimization Considerations . . . . . . . . . . . . . . . . . 14
6.1. Segment Protection Example with Common SRGB . . . . . . . 15
7. Operational Considerations . . . . . . . . . . . . . . . . . 16
8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
11.1. Normative References . . . . . . . . . . . . . . . . . . 17
11.2. Informative References . . . . . . . . . . . . . . . . . 17
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