Metadata Type Issues
draft-wang-sfc-md-type-issues-02

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SFC WG                                                           C. Wang
Internet-Draft                                                   W. Meng
Intended status: Standards Track                         ZTE Corporation
Expires: April 27, 2017                                 October 24, 2016

                          Metadata Type Issues
                    draft-wang-sfc-md-type-issues-02

Abstract

   Service function chain is the definition of an ordered set of service
   functions.  After instantiated, the service function path is created
   and the classified traffic is steered through the corresponding
   service function path and then forwarded to the final destination.
   Metadata (MD) is conveyed in SFC data plane which provides the
   ability to exchange context information between classifiers and SFs,
   among SFs, and between external systems and SFs.  This document is
   motivated to state an issue when MD Type = 0x1.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on April 27, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must

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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Convention and Terminology  . . . . . . . . . . . . . . . . .   3
   3.  An issue in MD-Type = 0x1 . . . . . . . . . . . . . . . . . .   4
   4.  An analysis on how to solve above issue . . . . . . . . . . .   6
     4.1.  Method 1  . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Method 2  . . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Gap analysis  . . . . . . . . . . . . . . . . . . . . . . . .   8
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Service function chain is the definition of an ordered set of service
   functions.  After instantiated, the service function path is created
   and the classified traffic is steered through the corresponding
   service function path and then forwarded to the final destination.

   Metadata is conveyed in the Context Headers in SFC data plane which
   provides the ability to exchange context information between
   classifiers and SFs, among SFs, and between external systems and SFs.
   In [I-D.ietf-sfc-nsh], it defines two mandate parts including Base
   Header and Service Path Header in NSH header.  Besides these two
   parts, there are Contexts Headers immediately following the Service
   Path Header as well.  As for what kinds of Contexts Headers is
   according to the MD Type specified in the Base Header.  In fact, it
   defines two MD types:

   When the Base Header specifies MD Type = 0x1, four Mandatory Context
   Headers must be added immediately following the Service Path Header,
   as per Figure 1.

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