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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. 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 April 13, 2020. Voyer, Ed., et al. Expires April 13, 2020 [Page 1] Internet-Draft SR Replication Segment October 2019 Copyright Notice Copyright (c) 2019 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 carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must 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. 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. Voyer, Ed., et al. Expires April 13, 2020 [Page 2] Internet-Draft SR Replication Segment October 2019 A Replication segment is identified by the tuple , 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 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 Voyer, Ed., et al. Expires April 13, 2020 [Page 3] Internet-Draft SR Replication Segment October 2019 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 Voyer, Ed., et al. Expires April 13, 2020 [Page 4] Internet-Draft SR Replication Segment October 2019 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, . [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, . Voyer, Ed., et al. Expires April 13, 2020 [Page 5] Internet-Draft SR Replication Segment October 2019 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 Voyer, Ed., et al. Expires April 13, 2020 [Page 6]