Multicast in SR Networks
draft-zzhang-pim-sr-multicast-00

Document Type Active Internet-Draft (individual)
Last updated 2018-08-15
Stream (None)
Intended RFC status (None)
Formats plain text pdf html bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date
Responsible AD (None)
Send notices to (None)
PIM                                                             Z. Zhang
Internet-Draft                                          Juniper Networks
Intended status: Informational                              IJ. Wijnands
Expires: February 16, 2019                                 Cisco Systems
                                                             A. Dolganow
                                                                   Nokia
                                                                 L. Geng
                                                            China Mobile
                                                         August 15, 2018

                        Multicast in SR Networks
                    draft-zzhang-pim-sr-multicast-00

Abstract

   With Segment Routing (SR) architecture [rfc8402], a unicast flow can
   be routed through an SR network following an explicit path specified
   in the packet, w/o the need for per-flow state in the network.  As a
   result, the otherwise needed protocols to signal the per-flow unicast
   state can also be removed from the network.  This document discusses
   options for multicast in an SR network.

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 February 16, 2019.

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
   (https://trustee.ietf.org/license-info) in effect on the date of

Zhang, et al.           Expires February 16, 2019               [Page 1]
Internet-Draft                SR-multicast                   August 2018

   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.  Traditional Multicast Technologies  . . . . . . . . . . . . .   2
   3.  Bit Index Explicit Replication  . . . . . . . . . . . . . . .   3
   4.  Multicast Trees Set up by Other Means . . . . . . . . . . . .   4
   5.  SR Specific Solutions . . . . . . . . . . . . . . . . . . . .   4
   6.  Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   9.  Informative References  . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   With Segment Routing (SR) architecture [RFC8402], a unicast flow can
   be routed through an SR network following an explicit path specified
   in the packet, w/o the need for per-flow state in the network.  As a
   result, the otherwise needed protocols to signal the per-flow unicast
   state can also be removed from the network.

   This document summarizes options for multicast in an SR network,
   including traditional multicast technologies, BIER, and various SR
   specific proposals.  The pros and cons of each solution are listed
   for considerations by operators and vendors.

2.  Traditional Multicast Technologies

   Traditional multicast technologies include PIM [RFC7761], RSVP-TE
   P2MP [RFC4875], and mLDP [RFC6388].  They all require per-tree state
   on nodes on the tree, and the corresponding protocols to signal and
   maintain the state.  An incoming packet's IP header or MPLS label is
   looked up, and the packet is forwarded according to the matched
   state.

   While SR allows simplification of state, protocols and centralized
   SDN-control, the traditional methods of delivering multicast traffic
   run contrary to those SR goals.

   An alternative is Ingress Replication (IR) - an upstream node of a
   multicast packet tunnels individual copies to some downstream nodes

Zhang, et al.           Expires February 16, 2019               [Page 2]
Internet-Draft                SR-multicast                   August 2018

   across some intermediate nodes.  In an SR network, the unicast
Show full document text