Metadata in SR Service Programming Considerations
draft-liu-spring-sr-sfc-metadata-00

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SPRING Working Group                                            Yao. Liu
Internet-Draft                                           ZTE Corporation
Intended status: Standards Track                           March 1, 2020
Expires: September 2, 2020

           Metadata in SR Service Programming Considerations
                  draft-liu-spring-sr-sfc-metadata-00

Abstract

   This document discusses different ways to carry metadata in SR
   service programming data plane.

Status of This Memo

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   This Internet-Draft will expire on September 2, 2020.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Metadata in SRV6 Data Plane . . . . . . . . . . . . . . . . .   2
   3.  Metadata in SR-MPLS Data Plane  . . . . . . . . . . . . . . .   2
     3.1.  Indicating Metadata in User Data Packets  . . . . . . . .   3
     3.2.  Per Packet Metadata . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Service Function Chaining (SFC)[7665] provides support for the
   creation of composite services that consist of an ordered set of
   Service Functions (SF) that are to be applied to packets and/or
   frames selected as a result of classification.
   [I-D.ietf-spring-sr-service-programming] describes how a service can
   be associated with a SID and how to achieve service funtion chaining
   in SR-enabled MPLS and IPv6 networks.  In the context of Service
   Function Chaining, metadata provides contextual information about the
   data packets which traverse a Service Function Chain.

   Metadata is defined in [RFC7665]as providing "the ability to exchange
   context information between classifiers and SFs, and among SFs."

   This document discusses ways to carry metadata in SR based SFC data
   plane, including SRv6 and SR-MPLS.

2.  Metadata in SRV6 Data Plane

   [I-D.ietf-spring-sr-service-programming] defines two SRv6 TLVs,
   Opaque Metadata TLV and NSH Carrier TLV, which are used to carry
   metadata in SRH.  Another way is to carry metadata via a separate
   header.  [I-D.li-6man-enhanced-extension-header] defines a new IPv6
   extension header called metadata header, and
   [I-D.li-6man-ipv6-sfc-ifit] defines a SFC Service Metadata Option in
   metadata header.

3.  Metadata in SR-MPLS Data Plane

   Currently there is no specific solution for MPLS-SR to carry
   metadata.

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3.1.  Indicating Metadata in User Data Packets

   [RFC8595]chapter 12 describe how metadata is associated with user
   data packets, when using an MPLS encoding of the logical
   representation of the NSH.  A similar approach can be used in SR-
   MPLS.

   For a better understanding, the main points of the scheme will be
   described below.

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