Network Service Header TLVs
draft-ietf-sfc-nsh-tlv-00

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Network Working Group                                           P. Quinn
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Standards Track                                U. Elzur
Expires: August 2, 2018                                            Intel
                                                                S. Majee
                                                                      F5
                                                        January 29, 2018

                      Network Service Header TLVs
                     draft-ietf-sfc-nsh-tlv-00.txt

Abstract

   This draft describes Network Service Header (NSH) MD-Type 2 metadata
   TLVs that can be used within a service function path.

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 August 2, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  NSH Type 2 Format . . . . . . . . . . . . . . . . . . . . . .   2
   3.  NSH Type 2 TLVs . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   5.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Network Service Header [NSH] is the SFC encapsulation protocol used
   to create Service Function Chains.  As such, NSH provides two key
   elements:

   1.  Service Function Path identification

   2.  Metadata

   NSH further defines two metadata formats (MD Types): 1 and 2.  MD
   Type 1 defines fixed length, 16 byte metadata, whereas MD Type 2
   defines a variable-length TLV format for metadata.  This draft
   defines some common TLVs for use with NSH MD Type 2.

   This draft does not address metadata usage, updating/chaining of
   metadata or other SFP functions.  Those topics are described in NSH.

2.  NSH Type 2 Format

   A NSH is composed of a 4-byte Base Header, a 4-byte Service Path
   Header and Context Headers.  The Base Header identifies the MD-Type
   in use:

       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Ver|O|C|R|R|R|R|R|R|   Length  |    MD Type    | Next Protocol |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 1: NSH Base Header

   Please refer to NSH [NSH] for a detailed header description.

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   When the base header specifies MD Type= 0x2, zero or more Variable
   Length Context Headers MAY be added, immediately following the
   Service Path Header.  Therefore, Length = 0x2, indicates that only
   the Base Header followed by the Service Path Header are present.  The
   number, indicated in the length field, of optional Variable Length
   Context Headers MUST be of an integer indicating length in 4-bytes
   words Figure 3 below depicts the format the context header.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1