Compressed Routing Header (CRH) Helper Option
draft-bonica-6man-crh-helper-opt-01

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6man WG                                                            X. Li
Internet-Draft                                                    C. Bao
Intended status: Standards Track       CERNET Center/Tsinghua University
Expires: November 5, 2020                                        E. Ruan
                                                           Fungible Inc.
                                                               R. Bonica
                                                        Juniper Networks
                                                             May 4, 2020

             Compressed Routing Header (CRH) Helper Option
                  draft-bonica-6man-crh-helper-opt-01

Abstract

   This document defines the IPv6 Compressed Routing Header (CRH) Helper
   option.  When a source node sends a packet with a CRH, it can use the
   CRH Helper option to provide additional information to downstream
   nodes.

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 November 5, 2020.

Copyright Notice

   Copyright (c) 2020 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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   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.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Option Format . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Option Processing . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   IPv6 [RFC8200] source nodes use the Compressed Routing Header (CRH)
   [I-D.bonica-6man-comp-rtg-hdr] to steer packets along a delivery path
   to their destination.  Two CRH versions have been defined.  The
   CRH-16 encodes segment endpoints in 16 bits, while CRH-32, encodes
   segment endpoints in 32 bits.

   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 packet's ultimate destination.

   o  Segment Identifier (SID) List - Represents the delivery 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
   represents an interface belonging to the node, the node processes the

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   next header.  If the next header is a CRH, it is processed as
   follows:

   o  If Segments Left equals 0, skip over the CRH and process the next
      header in the packet.

   o  Decrement Segments Left.

   o  Query a local data structure, called the CRH Forwarding
      Information Base (CRH-FIB), searching for an entry that is indexed
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