Signaling Composite Candidate Path of SR Policy using BGP-LS
draft-li-idr-bgpls-sr-policy-composite-path-00
Network Working Group H. Li
Internet-Draft M. Chen
Intended status: Standards Track C. Lin
Expires: August 6, 2021 H3C
February 2, 2021
Signaling Composite Candidate Path of SR Policy using BGP-LS
draft-li-idr-bgpls-sr-policy-composite-path-00
Abstract
Segment Routing is a source routing paradigm that explicitly
indicates the forwarding path for packets at the ingress node. An SR
Policy is associated with one or more candidate paths, and each
candidate path is either dynamic, explicit or composite. This
document specifies the extensions to BGP Link State (BGP-LS) to carry
composite candidate path information in the advertisement of an SR
policy.
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This Internet-Draft will expire on August 6, 2021.
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Internet-Draft Signal SR Policy Composite Path in BGP-LS February 2021
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. BGP-LS Extensions for Composite Candidate Path . . . . . . . 3
3.1. Constituent SR Policy TLV . . . . . . . . . . . . . . . . 3
4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
As described in [RFC7752], BGP Link State (BGP-LS) provides a
mechanism by which link-state and TE information can be collected
from networks and shared with external components using the BGP
routing protocol.
Segment routing (SR) [RFC8402] is a source routing paradigm that
explicitly indicates the forwarding path for packets at the ingress
node. The ingress node steers packets into a specific path according
to the Segment Routing Policy (SR Policy) as defined in
[I-D.ietf-spring-segment-routing-policy].
An SR Policy is associated with one or more candidate paths. A
composite candidate path acts as a container for grouping of SR
Policies. As described in section 2.2 in
[I-D.ietf-spring-segment-routing-policy], the composite candidate
path construct enables combination of SR Policies, each with explicit
candidate paths and/or dynamic candidate paths with potentially
different optimization objectives and constraints, for a load-
balanced steering of packet flows over its constituent SR Policies.
[I-D.ietf-idr-te-lsp-distribution] describes a mechanism to collect
the SR policy information that is locally available in a node and
advertise it into BGP-LS updates. This document extends it to
provide some extra information to carry composite candidate path
information in the BGP-LS advertisement.
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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