SRv6 for Inter-Layer Network Programming
draft-dong-spring-srv6-inter-layer-programming-01

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SPRING Working Group                                             J. Dong
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                                   Z. Du
Expires: May 4, 2021                                        China Mobile
                                                        October 31, 2020

                SRv6 for Inter-Layer Network Programming
           draft-dong-spring-srv6-inter-layer-programming-01

Abstract

   This document defines a new SRv6 network function which can be used
   for SRv6 inter-layer network programming.  It is a variant of the
   End.X function.  Instead of pointing to an L3 adjacency, this
   function points to an underlay interface.  Such a interface can stand
   for a underlay link or path/connection between two routers, which may
   be invisible in the L3 topology.

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Dong & Du                  Expires May 4, 2021                  [Page 1]
Internet-Draft    SRv6 Inter-Layer Network Programming      October 2020

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language and Terminology . . . . . . . . . . . .   3
   3.  END.XU Function . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Use Case for SRv6 Underlay Interface Function . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   In many scenarios, operator owns a multi-layered network.  In that
   case, cross-layer design and optimization mechanisms are more
   efficient in resource utilization and SLA assurance, but normally are
   also considered more complicated.  As an IP/MPLS based technology,
   Segment Routing (SR) normally does not need to care about the network
   layers beneath the IP layer.  One exception is as described in
   [RFC8668], IS-IS is extended to advertise the link attributes and
   Segment Identifiers (SIDs) of Layer 2 (L2) bundle members, so that
   operator can control traffic flows to traverse a particular
   individual L2 link which comprises the L2 bundle interface

   In [I-D.ietf-spring-srv6-network-programming], it is described that
   for an outgoing interface bundle made of 10 member links, up to 11
   End.X local SIDs for that bundle need to be allocated.  One END.X for
   the bundle itself and then up to one END.X for each member link.
   However, there are some differences between the normal END.X function
   for the bundle and the END.X function for the member link, as they
   are not at the same network layer.  Moreover, besides the L2 bundle
   use case, there are other types of underlay interfaces or
   connections, which can be integrated and programmed using SRv6.  This
   document aims to define a unified SRv6 function to support those
   inter-layer network programming in SRv6.

   As another example, the underlay of the IP network can be an optical
   network.  In many today's IP and optical transport networks, IP
   network and optical network are maintained separately, and in most
   cases, the optical network works as an underlay which is invisible to