Network Working Group D. Voyer, Ed.
Internet-Draft C. Hassen
Intended status: Standards Track K. Gillis
Expires: December 31, 2018 Bell Canada
C. Filsfils
A. Venkateswaran
Cisco Systems, Inc.
June 29, 2018
SR Replication Policy for P2MP Service Delivery
draft-voyer-spring-sr-p2mp-policy-00
Abstract
This document describes the SR policy architecture for P2MP service
delivery.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 31, 2018.
Copyright Notice
Copyright (c) 2018 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. SR Replication Policy . . . . . . . . . . . . . . . . . . . . 2
3. Spray SR Policy . . . . . . . . . . . . . . . . . . . . . . . 3
4. TreeSID - Controller Instantiated SR Tree . . . . . . . . . . 3
5. Illustration . . . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 4
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 4
10. Normative References . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
The document defines a variant of the SR Policy [I-D. ietf-spring-
segment-routing-policy] which allows for replication for supporting
point-to-multi-point service delivery. We call it an SR Replication
Policy.
We illustrate its use in two use-cases known as Spray and TreeSID.
Spray uses an SR Replication Policy to replicate a packet, at a given
node, along N SR paths to a set of leaf nodes.
In the TreeSID use-case, a controller computes a tree from a root to
a set of leaves and then programs each replication node of the tree
with an SR Replication Policy.
2. SR Replication Policy
This section is similar to section 2 of SR Policy draft
[I-D.ietf-spring-segment-routing-policy] and holds information that
applies equally to the Spray and TreeSID use-cases.
The SR Replication policy is a variant of an SR policy
[I-D.ietf-spring-segment-routing-policy], which provides packet
replication. A SR Replication Policy is identified through the tuple
<headend, color>.
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A SR Replication may comprise of multiple candidate paths. A
candidate path is valid when all its SID-Lists are valid. The active
candidate path is selected based on the tiebreaking rules amongst the
valid candidate-paths.
Each SID-List is additionally identified by a endpoint where its SR
path terminates. The endpoint could be the actual leaf of a P2MP
service delivery tree or it could be the headend of another SR
Replication Policy.
Any traffic steered into a SR Replication Policy is replicated along
the SID-Lists of its selected path towards the Leaf node.
In the context of a SR Replication Policy, the selected path MAY have
more than one SID-List. The weights of the SID-Lists is not
applicable for a SR Replication Policy. They MUST be set to 1.
Like any SR policy, a SR Replication Policy has a BSID
[I-D.ietf-spring-segment-routing-policy] instantiated into the
forwarding plane.
A SR replication policy can be provisioned either locally or setup
via controller.
Traffic is steered into a SR Replication Policy in two ways
o Based on a local policy-based routing at the Root node.
o Based on remote classification and steering via the BSID of the SR
Replication Policy.
3. Spray SR Policy
This is a use-case of the SR Replication Policy in which packet
replication occurs only at the Root node. A Spray SR Replication
policy is instantiated only at the Root node.
A packet, using this approach, is replicated directly to each Leaf
node via a segment routed path from the Root to a given Leaf node.
4. TreeSID - Controller Instantiated SR Tree
This is a use-case of the SR Replication policy in which packet
replication occurs at the Root node and on some downstream branch
points towards the Leaf node.
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A SR Replication policy instantiated on the Root node takes a packet
from the Root node to a set of branch points towards the Leaf node.
A branch point MAY also be a Leaf node.
Another SR Replication policy instantiated at each of these branch
points take the packet down further to other branch points or Leaf
nodes.
5. Illustration
TBD
6. IANA Considerations
This document makes no request of IANA.
7. Security Considerations
There are no additional security risks introduced by this design.
8. Acknowledgements
9. Contributors
10. Normative References
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Sivabalan, S., daniel.voyer@bell.ca, d.,
bogdanov@google.com, b., and P. Mattes, "Segment Routing
Policy Architecture", draft-ietf-spring-segment-routing-
policy-01 (work in progress), June 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
Authors' Addresses
Daniel Voyer (editor)
Bell Canada
Montreal
CA
Email: daniel.voyer@bell.ca
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Clayton Hassen
Bell Canada
Vancouver
CA
Email: clayton.hassen@bell.ca
Kurtis Gillis
Bell Canada
Halifax
CA
Email: kurtis.gillis@bell.ca
Clarence Filsfils
Cisco Systems, Inc.
Brussels
BE
Email: cfilsfil@cisco.com
Arvind Venkateswaran
Cisco Systems, Inc.
San Jose
US
Email: arvvenka@cisco.com
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