BGP Extension for SR-MPLS Entropy Label Position
draft-zhou-idr-bgp-srmpls-elp-02
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Liu Yao
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Shaofu Peng
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2021-02-22
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IDR Working Group Yao. Liu
Internet-Draft Shaofu. Peng
Intended status: Standards Track ZTE Corp.
Expires: August 26, 2021 February 22, 2021
BGP Extension for SR-MPLS Entropy Label Position
draft-zhou-idr-bgp-srmpls-elp-02
Abstract
This document proposes extensions for BGP to indicate the entropy
label position in the SR-MPLS label stack when distributing SR Policy
candidate paths.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on August 26, 2021.
Copyright Notice
Copyright (c) 2021 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
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
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Liu & Peng Expires August 26, 2021 [Page 1]
Internet-Draft BGP Extension for ELP February 2021
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.2. Terminology and Acronyms . . . . . . . . . . . . . . . . 3
3. Entropy Labels in SR-MPLS Scenario with a Controller . . . . 3
4. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . 4
5. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Segment Routing (SR) leverages the source routing paradigm. Segment
Routing can be instantiated on MPLS data plane which is referred to
as SR-MPLS [RFC8660]. SR-MPLS leverages the MPLS label stack to
construct the SR path.
Entropy labels (ELs) [RFC6790] are used in the MPLS data plane to
provide entropy for load-balancing. The idea behind the entropy
label is that the ingress router computes a hash based on several
fields from a given packet and places the result in an additional
label named "entropy label". Then, this entropy label can be used as
part of the hash keys used by an LSR. Using the entropy label as
part of the hash keys reduces the need for deep packet inspection in
the LSR while keeping a good level of entropy in the load-balancing.
[RFC8662] proposes to use entropy labels for SR-MPLS networks and
mutiple < ELI, EL> pairs may be inserted in the SR-MPLS label stack.
The ingress node may decide the number and position of the ELI/ELs
which need to be inserted into the label stack, that is termed as ELP
(Entropy Label Position). In some cases, centralized controllers are
used to perform the TE path computation for intra or inter-domain
scenarios, thus it is also the responsibility of the controller to
calculate ELP and inform it to the headend of the SR-TE path.
[I-D.ietf-idr-segment-routing-te-policy] defines the specific process
of how the controller/PCE in the SR network passes the path
calculation result of the SR-TE policy to the headend of the network
through BGP.
Liu & Peng Expires August 26, 2021 [Page 2]
Internet-Draft BGP Extension for ELP February 2021
This document proposes extensions for BGP to indicate the ELP in the
segment list when distribute SR Policy candidate paths using BGP for
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