SR-TE Path Midpoint Protection
draft-hu-spring-segment-routing-proxy-forwarding-09
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2020-07-10
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Network Working Group Z. Hu
Internet-Draft Huawei Technologies
Intended status: Standards Track H. Chen
Expires: January 11, 2021 Futurewei
J. Yao
Huawei Technologies
C. Bowers
Juniper Networks
Y. Zhu
China Telecom
July 10, 2020
SR-TE Path Midpoint Protection
draft-hu-spring-segment-routing-proxy-forwarding-09
Abstract
Segment Routing Traffic Engineering (SR-TE) supports the creation of
explicit paths using segment lists containing adjacency-SIDs, node-
SIDs, anycast-SIDs, and binding-SIDs. When the segment list defining
an SR-TE path contains a node-SID, and the node fails, the network
may no longer be able to properly forward traffic on that SR-TE path.
[I-D.ietf-rtgwg-segment-routing-ti-lfa] and
[I-D.hegde-spring-node-protection-for-sr-te-paths] describe a
mechanism that allows local repair actions on the direct neighbors of
the failed node to temporarily route traffic to the node immediately
following the failed node on the SR-TE path segment list. However,
once the IGP shortest paths have converged, the local repair
mechanism is no longer sufficient to continue forwarding traffic
using the original segment list of the SR-TE path, since the non-
neighbors of the failed node will no longer have a route to reach the
failed node. This document describes a mechanism that allows traffic
to continue to be forwarded on an SR-TE path for an extended period
of time after the failure of a node used in the path's segment list.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Hu, et al. Expires January 11, 2021 [Page 1]
Internet-Draft SR-TE Midpoint Protection July 2020
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Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Extensions to IGP for Proxy Forwarding . . . . . . . . . . . 4
2.1. Extensions to OSPF . . . . . . . . . . . . . . . . . . . 4
2.1.1. Advertising Proxy Forwarding . . . . . . . . . . . . 4
2.1.2. Advertising Binding Segment . . . . . . . . . . . . . 7
2.2. Extensions to IS-IS . . . . . . . . . . . . . . . . . . . 9
2.2.1. Advertising Proxy Forwarding . . . . . . . . . . . . 9
2.2.2. Advertising Binding Segment . . . . . . . . . . . . . 11
3. Building Proxy Forwarding Table . . . . . . . . . . . . . . . 13
3.1. Advertising Proxy Forwarding . . . . . . . . . . . . . . 15
3.2. Building Proxy Forwarding Table . . . . . . . . . . . . . 15
4. Node Protection for Segment List . . . . . . . . . . . . . . 15
4.1. Next Segment is an Adjacency Segment . . . . . . . . . . 16
4.2. Next Segment is a Node Segment . . . . . . . . . . . . . 16
4.3. Next Segment is a Binding Segment . . . . . . . . . . . . 17
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