Network Services Header Context Allocation Identifier
draft-vandevelde-sfc-nsh-length-overload-00

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Last updated 2016-10-17
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SFC Working Group                                   G. Van de Velde, Ed.
Internet-Draft                                              M. Vigoureux
Intended status: Standards Track                                P. Mulay
Expires: April 20, 2017                                            Nokia
                                                        October 17, 2016

         Network Services Header Context Allocation Identifier
              draft-vandevelde-sfc-nsh-length-overload-00

Abstract

   The specification of the NSH MD Type 1 header [draft-ietf-sfc-nsh]
   mandates four Context Headers, 4-byte each, and they MUST be added
   immediately following the Service Path Header.  As direct
   consequence, an NSH MD Type 1 header is always Length 0x6 (six 4-byte
   words).  As a result, the Length field of the NSH MD Type 1 header
   provides an information which is known by simply looking at the "MD
   Type" field.  However, while [draft-ietf-sfc-nsh] does not specify
   the encoding of these Context Headers, other specifications have
   started to do so.  A need to distinguish types of Context Headers
   therefore arises.

   This draft proposes to overload the Length field of an NSH MD Type 1
   as Meta-Data context allocation identifier and to create a IANA
   repository for NSH MD Type 1 allocation schemes.  The NSH MD Type 1
   Length field overload intends to allow universal understanding at any
   network location and by any network device of the context allocation
   structure.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [1].

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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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any

Van de Velde, et al.     Expires April 20, 2017                 [Page 1]
Internet-Draft NSH MD Type-1 Context Allocation Identifier  October 2016

   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 20, 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   The specification of the NSH MD Type 1 header [draft-ietf-sfc-nsh]
   mandates four Context Headers, 4-byte each, and they MUST be added
   immediately following the Service Path Header.  As direct
   consequence, an NSH MD Type 1 header is always Length 0x6 (six 4-byte
   words).  As a result, the Length field of the NSH MD Type 1 header
   provides an information which is known by simply looking at the "MD
   Type" field.  However, while [draft-ietf-sfc-nsh] does not specify
   the encoding of these Context Headers, other specifications have
   started to do so.  A need to distinguish types of Context Headers
   therefore arises.

   This draft proposes to overload the Length field of an NSH MD Type 1
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