Compressed Routing Header (CRH) Helper Option
draft-bonica-6man-crh-helper-opt-02
6man WG X. Li
Internet-Draft C. Bao
Intended status: Standards Track CERNET Center/Tsinghua University
Expires: April 29, 2021 E. Ruan
Fungible Inc.
R. Bonica
Juniper Networks
October 26, 2020
Compressed Routing Header (CRH) Helper Option
draft-bonica-6man-crh-helper-opt-02
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 April 29, 2021.
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Internet-Draft CRH Helper Option October 2020
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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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