Integration of Network Service Header (NSH) and Segment Routing for Service Function Chaining (SFC)
draft-ietf-spring-nsh-sr-03

Document Type Active Internet-Draft (spring WG)
Authors Jim Guichard  , Jeff Tantsura 
Last updated 2020-09-25
Replaces draft-guichard-spring-nsh-sr
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SPRING                                                  J. Guichard, Ed.
Internet-Draft                                    Futurewei Technologies
Intended status: Standards Track                        J. Tantsura, Ed.
Expires: March 28, 2021                                      Apstra inc.
                                                      September 24, 2020

  Integration of Network Service Header (NSH) and Segment Routing for
                    Service Function Chaining (SFC)
                      draft-ietf-spring-nsh-sr-03

Abstract

   This document describes two application scenarios where Network
   Service Header (NSH) and Segment Routing (SR) can be deployed
   together to support Service Function Chaining (SFC) in an efficient
   manner while maintaining separation of the service and transport
   planes as originally intended by the SFC architecture.

   In both scenarios, SR is responsible for steering packets between
   SFFs along a given Service Function Path (SFP) while NSH is
   responsible for maintaining the integrity of the service plane, the
   SFC instance context, and any associated metadata.

   These application scenarios demonstrate that NSH and SR can work
   jointly and complement each other leaving the network operator with
   the flexibility to use whichever transport technology makes sense in
   specific areas of their network infrastructure, and still maintain an
   end-to-end service plane using NSH.

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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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 28, 2021.

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Internet-Draft                 NSH-SR SFC                 September 2020

Copyright Notice

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   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  SFC Overview and Rationale  . . . . . . . . . . . . . . .   2
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  SFC within Segment Routing Networks . . . . . . . . . . . . .   4
   3.  NSH-based SFC with SR-based Transport Tunnel  . . . . . . . .   5
   4.  SR-based SFC with Integrated NSH Service Plane  . . . . . . .   9
   5.  Encapsulation Details . . . . . . . . . . . . . . . . . . . .  11
     5.1.  NSH using SR-MPLS Transport . . . . . . . . . . . . . . .  11
     5.2.  NSH using SRv6 Transport  . . . . . . . . . . . . . . . .  12
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
     7.1.  UDP Port Number for NSH . . . . . . . . . . . . . . . . .  13
     7.2.  Protocol Number for NSH . . . . . . . . . . . . . . . . .  14
   8.  Contributing Authors  . . . . . . . . . . . . . . . . . . . .  14
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  15
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

1.1.  SFC Overview and Rationale

   The dynamic enforcement of a service-derived, adequate forwarding
   policy for packets entering a network that supports advanced Service
   Functions (SFs) has become a key challenge for network operators.
   Particularly, cascading SFs at the so-called Third Generation
   Partnership Project (3GPP) Gi interface in the context of mobile
   network infrastructure, have shown their limitations, such as the
   same redundant classification features must be supported by many SFs
   to execute their function, some SFs are receiving traffic that they

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