SRv6 vSID: Network Programming extension for variable length SIDs
draft-decraene-spring-srv6-vlsid-02

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Network Working Group                                        B. Decraene
Internet-Draft                                                    Orange
Intended status: Standards Track                               R. Raszuk
Expires: August 8, 2020                                        Bloomberg
                                                        February 5, 2020

   SRv6 vSID: Network Programming extension for variable length SIDs
                  draft-decraene-spring-srv6-vlsid-02

Abstract

   This document proposes an extension to Segment Routing IPv6 (SRv6)
   Network Programming to allow for SRv6 Segment Identifier (SID) of
   smaller variable length.  The use of smaller SRv6 SID reduces the
   size the SRv6 Header (SRH).  This reduces the overhead for both the
   traffic volume and the network processor.  It is a straightforward
   extension to the SRv6 Network Programming model and its SRH
   encapsulation.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SRv6 Variable Length SIDs . . . . . . . . . . . . . . . . . .   4
     3.1.  Encoding vSIDs in the SRH . . . . . . . . . . . . . . . .   5
     3.2.  SRv6 vSIDs Network Programming  . . . . . . . . . . . . .   7
   4.  Benefits  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   5.  Illustrations . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Global vSIDs  . . . . . . . . . . . . . . . . . . . . . .   9
     5.2.  Local vSIDs . . . . . . . . . . . . . . . . . . . . . . .  10
   6.  Signaling vSIDs length  . . . . . . . . . . . . . . . . . . .  11
     6.1.  Signaling vSIDs length in IS-IS . . . . . . . . . . . . .  11
   7.  A node requiring a larger vSIDs length. . . . . . . . . . . .  12
     7.1.  Allocating a larger locator to a node.  . . . . . . . . .  12
     7.2.  Combining k vSIDs to identify a behavior. . . . . . . . .  12
   8.  Inter Routing Domains . . . . . . . . . . . . . . . . . . . .  13
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  15
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  15
   12. Changes / Authors Notes . . . . . . . . . . . . . . . . . . .  15
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  16
     13.2.  Informative References . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   The Segment Routing (SR) architecture is defined RFC 8402 [RFC8402].

   IPv6 Segment Routing Header (SRH) is defined
   [I-D.ietf-6man-segment-routing-header].

   SRv6 Network Programming is defined
   [I-D.ietf-spring-srv6-network-programming].

   The reader is expected to be familiar with the three above documents
   which define Segment Routing over the IPv6 data-plane (SRv6).

   SRv6 is flexible and powerful, but in some uses cases, when a large
   number of SIDs are required, the size of the SRH/SID may be seen as
   too large both for some dataplane processors and traffic overhead.

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