Signalling ERLD using BGP-LS
draft-ietf-idr-bgp-ls-segment-routing-rld-01
IDR Working Group G. Van de Velde, Ed.
Internet-Draft W. Henderickx
Intended status: Standards Track M. Bocci
Expires: June 21, 2018 Nokia
K. Patel
Arrcus
December 18, 2017
Signalling ERLD using BGP-LS
draft-ietf-idr-bgp-ls-segment-routing-rld-01
Abstract
This document defines the attributes to use for BGP-LS to expose ERLD
"Entropy capable Readable Label Depth" from a node or link to a
centralised controller (PCE/SDN).
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 [1].
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
4. ERLD support by a node . . . . . . . . . . . . . . . . . . . 3
5. ERLD support by a link . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
When Segment Routing tunnels are computed by a centralised
controller, it is beneficial that the controller knows the ERLD
(Entropy capable Readable Label Depth) of each node or link a tunnel
traverses. A network node signalling an ERLD MUST support the
ability to read the signalled number of labels before any action is
done upon the packet and SHOULD support entropy awareness found
within the signalled ERLD depth.
ERLD awareness of each node and link will allow a network SDN
controller to influence the path used for each tunnel. The SDN
controller may for example only create tunnels with a label stack
smaller or equal as the ERLD of each node and link on the path. This
will allow the network to behave accordingly (e.g. make use of
Entropy Labels to improve ECMP) upon the imposed Segment Routing
label stack on each packet.
This document describes how to use BGP-LS to expose the ERLD of a
node.
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2. Conventions used in this document
2.1. Terminology
BGP-LS: Distribution of Link-State and TE Information using Border
Gateway Protocol
ERLD: Entropy capable Readable Label Depth
PCC: Path Computation Client
PCE: Path Computation Element
PCEP: Path Computation Element Protocol
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