Multicast Routing In Fat Trees
draft-zzhang-rift-multicast-01

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RIFT                                                            Z. Zhang
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                              P. Thubert
Expires: January 14, 2021                                          Cisco
                                                           July 13, 2020

                     Multicast Routing In Fat Trees
                     draft-zzhang-rift-multicast-01

Abstract

   This document specifies multicast procedures with RIFT.  Multicast in
   RIFT is similar to Bidirectional Protocol Independent Multicast (PIM-
   Bidir), with the Rendezvous Point Link (RP-Link) simulated by a
   spanning tree of some Top of Fabric (TOF) nodes and sub-TOF nodes.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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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   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 January 14, 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Zhang & Thubert         Expires January 14, 2021                [Page 1]
Internet-Draft                    mrift                        July 2020

   This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Specifications  . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Multicast Capability  . . . . . . . . . . . . . . . . . .   4
     2.2.  Optional Per-neighbor Flooding Scope  . . . . . . . . . .   5
     2.3.  Multicast TIE . . . . . . . . . . . . . . . . . . . . . .   5
     2.4.  Building Spanning Tree among TOFs and sub-TOFs  . . . . .   6
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Because of the simple north-south regular topology in Fat Tree
   networks, the PIM-Bidir [RFC5015] solution is extended for multicast
   in RIFT (referred to as MRIFT in this document).  The following is a
   summary of the changes and adaptations compared to PIM-Bidir.

   With PIM-Bidir, PIM joins are sent towards a Rendezvous Point Address
   (RPA), which could be an address not belonging to any router.  The
   RPA does belong to a RP Link (RPL), which could be attached to a
   single router or multiple routers (e.g.  RPL is a LAN).  With MRIFT,
   there is no concept of RPA any more (joins are simply sent
   northbound).  The joins are terminated on some sub-TOF nodes and the
   RPL is simulated by a spanning tree among some TOF and sub-TOF nodes.

   Instead of (*,G) trees in PIM-Bidir, MRIFT uses (*,G-Prefix) trees,
   where the G-Prefix could be *, G, or anything in between (e.g.,
   225.1.1.0/24).  For light flows, they could just follow the (*,*)
   tree.  For heavy flows, individual (*,G) trees could be built.  For
   medium flows, some (*,G-prefix) trees could be shared.  All the First
   Hop Routers (FHRs, connecting to sources) and the Last Hop Routers
   (LHRs, connecting to receivers) of a particular (*,G) flow must agree
   on whether a (*,*) or (*,G) or (*,G-prefix) tree is used for the flow