Compressed Routing Header (CRH) Helper Option
draft-bonica-6man-crh-helper-opt-00

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6man WG                                                            X. Li
Internet-Draft                                                    C. Bao
Intended status: Standards Track       CERNET Center/Tsinghua University
Expires: May 3, 2020                                             E. Ruan
                                                           Fungible Inc.
                                                               R. Bonica
                                                        Juniper Networks
                                                        October 31, 2019

             Compressed Routing Header (CRH) Helper Option
                  draft-bonica-6man-crh-helper-opt-00

Abstract

   This document defines the IPv6 CRH Helper option.  When an SRm6
   ingress node originates a packet, it can use the IPv6 CRH Helper
   option to provide SID Forwarding Information Base (SFIB) information
   to downstream nodes that do not maintain a complete SFIB.

Status of This Memo

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   This Internet-Draft will expire on May 3, 2020.

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   Copyright (c) 2019 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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   include Simplified BSD License text as described in Section 4.e of
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Option Format . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Option Processing . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   SRm6 [I-D.bonica-spring-srv6-plus] leverages two new IPv6 [RFC8200]
   Routing types.  Generically, they are called the Compressed Routing
   Header (CRH) [I-D.bonica-6man-comp-rtg-hdr].  More specifically, the
   16-bit version of the CRH is called the CRH-16, while the 32-bit
   version of the CRH is called the CRH-32.

   Both CRH versions contain the following fields:

   o  Next Header - Identifies the header immediately following the CRH.

   o  Hdr Ext Len - Length of the CRH.

   o  Routing Type - Identifies the Routing header variant (i.e., CRH-16
      or CRH-32).

   o  Segments Left - The number of segments still to be traversed
      before reaching the SRm6 path egress node.

   o  Segment Identifier (SID) List - Represents the SRm6 path as an
      ordered list of Segment Identifiers (SID).  SIDs are listed in
      reverse order, with SID[0] representing the final segment, SID[1]
      representing the penultimate segment, and so forth.  SIDs are
      listed in reverse order so that Segments Left can be used as an
      index to the SID List.  The SID indexed by Segments Left is called
      the current SID.

   As per [RFC8200], when an IPv6 node receives a packet, it examines
   the packet's destination address.  If the destination address

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   represents an interface belonging to the node, the node processes the
   next header.  If the node encounters and recognizes the CRH, it
   processes the CRH as follows:

   o  If Segments Left equal 0, skip over the CRH and process the next
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