Network Working Group D. Voyer, Ed.
Internet-Draft Bell Canada
Intended status: Standards Track C. Filsfils
Expires: April 13, 2020 R. Parekh
Cisco Systems, Inc.
H. Bidgoli
Nokia
Z. Zhang
Juniper Networks
October 11, 2019
SR Replication Segment for Multi-point Service Delivery
draft-voyer-spring-sr-replication-segment-00
Abstract
This document describes the SR Replication segment for Multi-point
service delivery. A SR Replication segment allows a packet to be
replicated from a Replication node to downstream nodes.
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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This Internet-Draft will expire on April 13, 2020.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Replication segment . . . . . . . . . . . . . . . . . . . . . 2
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
We define a new type of segment for Segment Routing [RFC8402], called
Replication segment, which allows a node (henceforth called as
Replication node) to replicate packets to a set of other nodes
(called Downstream nodes) in a Segment Routing Domain. Replication
segments provide building blocks for Point-to-Multi-point Service
delivery. A Replication segment at ingress node of Multi-point
service replicates packets directly to each egress node of the
service, without need for any state in the core of SR domain.
Multiple Replication segments can be stitched together to build a
tree in SR domain for Multi-point service; this is outside the scope
of this document.
2. Replication segment
In a Segment Routing Domain, a Replication segment is a logical
segment which connects a Replication node to a set of Downstream
nodes. A Replication segment can be either provisioned locally on a
node or programmed by a PCE. Replication segments apply equally to
both SR-MPLS and SRv6 instantiations of Segment Routing.
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A Replication segment is identified by the tuple <Replication-ID,
Node-ID>, where:
o Replication-ID: An identifier for a Replication segment that is
unique in context of the Replication node. This is an unsigned
32-bit number.
o Node-ID: The address of a node at which a Replication segment is
instantiated. Replication segment is instantiated at Downstream
nodes and at the Replication node.
The Replicaion-ID can be extended or modified as required based on
specific use of a Replication segment.
A Replication segment is defined by following elements:
o Replication SID: The Segment Identifier of a Replication Segment.
This is a SR-MPLS label or a SRv6 SID [RFC8402].
o Downstream Nodes: Set of nodes in Segment Routing domain to which
a packet is replicated by the Replication segment.
o Replication State: See below.
Replication state is a list of Replication branches to the Downstream
nodes. In this document, each branch is abstracted to a <Downstream
Node, Downstream Replication-SID> tuple. A Replication branch to a
particular Downstream Node could be represented by the node's Node
SID (i.e. it does not matter how traffic gets to the Downstream node,
whether it's directly connected or not), or in case of a directly
connected node it could be represented by the Adjacency SID (for the
interface connecting to the directly connected Leaf Node).
Alternatively, the Downstream Node could also be expanded to a SID-
list that partially/fully specifies the explicit path to it. A
Replication branch can also use a Segment Routing Policy
[I-D.ietf-spring-segment-routing-policy], if available, from the
Replication node to the Downstream node.
Replication SID identifies the Replication Segment in the forwarding
plane. The Replication SID SHOULD be considered to be the equivalent
of Binding SID [I-D.ietf-spring-segment-routing-policy] of a Segment
Routing Policy, when Replication Segment is instantiated at Ingress
node of a Multi-point service. At Downstream nodes, the Replication
SID MAY be used to identify the Multi-point service.
A packet steered into a Replication Segment at a node is replicated
to each Downstream node with the Downstream Replication SID that is
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relevant at that node . A packet is steered into a Replication
Segment in two ways:
o Based on a local policy-based routing at Replication node.
o When the Active Segment [RFC8402] at Replication node is the
Replication SID.
3. IANA Considerations
This document makes no request of IANA.
4. Security Considerations
There are no additional security risks introduced by this design.
5. Acknowledgements
The authors would like to acknowledge Siva Sivabalan, Mike Koldychev
and Vishnu Pavan Beeram for their valuable inputs.
6. Contributors
Clayton Hassen
Bell Canada
Vancouver
Canada
Email: clayton.hassen@bell.ca
Kurtis Gillis
Bell Canada
Halifax
Canada
Email: kurtis.gillis@bell.ca
Arvind Venkateswaran
Cisco Systems, Inc.
San Jose
US
Email: arvvenka@cisco.com
Zafar Ali
Cisco Systems, Inc.
US
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Email: zali@cisco.com
Swadesh Agrawal
Cisco Systems, Inc.
San Jose
US
Email: swaagraw@cisco.com
Jayant Kotalwar
Nokia
Mountain View
US
Email: jayant.kotalwar@nokia.com
Tanmoy Kundu
Nokia
Mountain View
US
Email: tanmoy.kundu@nokia.com
Tarek Saad
Juniper Networks
Canada
Email:tsaad@juniper.net
7. 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-03 (work in progress), May 2019.
[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>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
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Authors' Addresses
Daniel Voyer (editor)
Bell Canada
Montreal
CA
Email: daniel.voyer@bell.ca
Clarence Filsfils
Cisco Systems, Inc.
Brussels
BE
Email: cfilsfil@cisco.com
Rishabh Parekh
Cisco Systems, Inc.
San Jose
US
Email: riparekh@cisco.com
Hooman Bidgoli
Nokia
Ottawa
CA
Email: hooman.bidgoli@nokia.com
Zhaohui Zhang
Juniper Networks
Email: zzhang@juniper.net
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