Network Working Group M. McBride
Request for Comments: 4611 J. Meylor
BCP: 121 D. Meyer
Category: Best Current Practice August 2006
Multicast Source Discovery Protocol (MSDP) Deployment Scenarios
Status of This Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document describes best current practices for intra-domain and
inter-domain deployment of the Multicast Source Discovery Protocol
(MSDP) in conjunction with Protocol Independent Multicast Sparse Mode
(PIM-SM).
Table of Contents
1. Introduction ....................................................2
1.1. BCP, Experimental Protocols, and Normative References ......3
2. Inter-domain MSDP Peering Scenarios .............................4
2.1. Peering between PIM Border Routers .........................4
2.2. Peering between Non-Border Routers .........................5
2.3. MSDP Peering without BGP ...................................7
2.4. MSDP Peering at a Multicast Exchange .......................7
3. Intra-domain MSDP Peering Scenarios .............................7
3.1. Peering between MSDP- and MBGP-Configured Routers ..........8
3.2. MSDP Peer Is Not BGP Peer (or No BGP Peer) .................8
3.3. Hierarchical Mesh Groups ...................................9
3.4. MSDP and Route Reflectors .................................10
3.5. MSDP and Anycast RPs ......................................11
4. Security Considerations ........................................11
4.1. Filtering SA Messages .....................................11
4.2. SA Message State Limits ...................................12
5. Acknowledgements ...............................................12
6. References .....................................................12
6.1. Normative References ......................................12
6.2. Informative References ....................................13
McBride, et al. Best Current Practice [Page 1]
RFC 4611 MSDP Deployment Scenarios August 2006
1. Introduction
MSDP [RFC3618] is used primarily in two deployment scenarios:
o Between PIM Domains
MSDP can be used between Protocol Independent Multicast Sparse
Mode (PIM-SM) [RFC4601] domains to convey information about active
sources available in other domains. MSDP peering used in such
cases is generally one-to-one peering, and utilizes the
deterministic peer-RPF (Reverse Path Forwarding) rules described
in the MSDP specification (i.e., it does not use mesh-groups).
Peerings can be aggregated on a single MSDP peer. Such a peer can
typically have from one to hundreds of peerings, which is similar
in scale to BGP peerings.
o Within a PIM Domain
MSDP is often used between Anycast Rendezvous Points (Anycast-RPs)
[RFC3446] within a PIM domain to synchronize information about the
active sources being served by each Anycast-RP peer (by virtue of
IGP reachability). MSDP peering used in this scenario is
typically based on MSDP mesh groups, where anywhere from two to
tens of peers can comprise a given mesh group, although more than
ten is not typical. One or more of these mesh-group peers may
also have additional one-to-one peerings with MSDP peers outside
that PIM domain for discovery of external sources. MSDP for
anycast-RP without external MSDP peering is a valid deployment
option and common.
Current best practice for MSDP deployment utilizes PIM-SM and the
Border Gateway Protocol with multi-protocol extensions (MBGP)
[RFC4271, RFC2858]. This document outlines how these protocols work
together to provide an intra-domain and inter-domain Any Source
Multicast (ASM) service.
The PIM-SM specification assumes that SM operates only in one PIM
domain. MSDP is used to enable the use of multiple PIM domains by
distributing the required information about active multicast sources
to other PIM domains. Due to breaking the Internet multicast
infrastructure down to multiple PIM domains, MSDP also enables the
possibility of setting policy on the visibility of the groups and
sources.
Transit IP providers typically deploy MSDP to be part of the global
multicast infrastructure by connecting to their upstream and peer
datatracker.ietf.org