SR Policy for Reverse Path
draft-lp-spring-sr-policy-reverse-path-00
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Active Internet-Draft (individual)
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Liu Yao
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Shaofu Peng
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2021-01-27
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SPRING WG Y. Liu
Internet-Draft S. Peng
Intended status: Standards Track ZTE Corporation
Expires: July 31, 2021 January 27, 2021
SR Policy for Reverse Path
draft-lp-spring-sr-policy-reverse-path-00
Abstract
This document introduces a method of dynamically configuring the
return path for an SR path.
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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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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 July 31, 2021.
Copyright Notice
Copyright (c) 2021 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
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Liu & Peng Expires July 31, 2021 [Page 1]
Internet-Draft SR Policy for Reverse Segment List January 2021
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. SR Policy for Bidirectional Path . . . . . . . . . . . . . . 2
2.1. BGP Extensions for Advertising Segment List . . . . . . . 3
2.2. Illustration . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Difference from Path Segment . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Echo-BFD [RFC5880] can be used to monitor an SR Policy between the
local and the remote BFD peers. As defined in [RFC5880], the remote
BFD system does not process the payload of an Echo BFD.
A BSID can be used to specify the return path of an Echo BFD packet.
As introduced in [I-D.ietf-spring-bfd], the sender MAY use a Binding
SID (BSID) [RFC8402] that has been bound with the SR Policy that
ensures the return of a packet to that particular node and a BSID MAY
be associated with the SR Policy that is the reverse to the SR Policy
programmed onto the BFD Echo packet by the sender.
One way to implement this is through static configuration, e.g,
configure the BSID corresponding to the return path for each segment
list when enable BFD for an SR policy or an segment list.
This document introduces a method of dynamically configuring the
return path for an SR path, which can be used to specify the return
path in Echo BFD for SR, ICMPv6 for SRv6, etc.
2. SR Policy for Bidirectional Path
In order to specify the return path for an segment list when
delivering the SR Policy, and the tail node can return the packet
according to the specified return path, this document proposes
extensions of SR Policy. It allows the segment list to have its own
BSID.
When delivering SR policy, the BSID of the segment list and the
corresponding BSID of the return segment list can be carried
together.
Liu & Peng Expires July 31, 2021 [Page 2]
Internet-Draft SR Policy for Reverse Segment List January 2021
2.1. BGP Extensions for Advertising Segment List
Segment List sub-TLV is introduced in
[I-D.ietf-idr-segment-routing-te-policy] and it includes the elements
of the paths (i.e., segments).
This document introduces two optional sub-sub-tlvs of Segment List
sub-TLV, Binding SID Sub-TLV and Reverse Binding SID Sub-TLV.
The Binding SID sub-TLV has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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