Anycast Segments in MPLS based Segment Routing
draft-psarkar-spring-mpls-anycast-segments-01
SPRING Working Group P. Sarkar, Ed.
Internet-Draft Juniper Networks, Inc.
Intended status: Standards Track H. Gredler
Expires: April 11, 2016 Individual Contributor
C. Filsfils
S. Previdi
Cisco Systems, Inc.
B. Decraene
Orange
M. Horneffer
Deutsche Telekom
October 9, 2015
Anycast Segments in MPLS based Segment Routing
draft-psarkar-spring-mpls-anycast-segments-01
Abstract
Instead of forwarding to a specific device or to all devices in a
group, anycast addresses, let network devices forward a packet to (or
steer it through) one or more topologically nearest devices in a
specific group of network devices. The use of anycast addresses has
been extended to the Segment Routing (SR) network, wherein a group of
SR-capable devices can represent a anycast address, by having the
same Segment Routing Global Block (SRGB) provisioned on all the
devices and each one of them advertising the same anycast prefix
segment (or Anycast SID).
This document describes a proposal for implementing anycast prefix
segments in a MPLS-based SR network, without the need to have the
same SRGB block (label ranges) provisioned across all the member
devices in the group. Each node can be provisioned with a separate
SRGB from the label range supported by the specfic hardware platform.
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.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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This Internet-Draft will expire on April 11, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 7
3.1.1. Common Anycast SRGB (CA-SRGB) . . . . . . . . . . . . 7
3.1.2. Common Anycast Prefix Segment Label (CAPSL) . . . . . 8
3.1.3. Anycast Prefix Segment Label (APSL) . . . . . . . . . 8
3.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.1. Label Stack Computation . . . . . . . . . . . . . . . 9
3.2.2. Virtual SID Label Lookup Table . . . . . . . . . . . 10
3.2.3. Advertising Anycast Prefix Segments . . . . . . . . . 13
3.2.4. Programming Anycast Prefix Segments . . . . . . . . . 14
3.3. Packet Flow . . . . . . . . . . . . . . . . . . . . . . . 16
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 17
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
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