Draft-Rosen Multicast VPNs Overview

The JUNOS software provides three ways to configure IP version 4 (IPv4) multicast over Layer 3 VPNs:

• Draft-rosen multicast VPNs—Described in RFC 4364, BGP/MPLS IP Virtual Private Networks (VPNs) and based on the IETF Internet draft draft-rosen-vpn-mcast-07.txt, Multicast in MPLS/BGP IP VPNs. Draft-rosen multicast VPNs can be configured with service provider tunnels operating in any-source multicast (ASM) mode or source-specific multicast (SSM) mode. For more information about these types of draft-rosen multicast VPNs, see the JUNOS Feature Guide.
• Draft-rosen multicast VPNs—Described in RFC 4364, BGP/MPLS IP Virtual Private Networks (VPNs) and based on Section Two of the IETF Internet draft draft-rosen-vpn-mcast-06.txt, Multicast in MPLS/BGP VPNs (expires April 2004).
• Multiprotocol BGP-based multicast VPNs (also referred to as next-generation Layer 3 VPN multicast)—Defined by a set of sender sites and a set of receiver sites, they use BGP as the signaling protocol. For more information about multiprotocol BGP-based multicast VPNs, see the JUNOS VPNs Configuration Guide.

Draft-rosen multicast VPN (MVPNs) with service provider tunnels operating in SSM mode do not require that the provider (P) routers maintain any VPN-specific PIM information.

Draft-rosen MVPNs with service provider tunnels operating in SSM mode, make use of two types of multicast distribution trees (MDTs); a default MDT and one or more data MDTs.

Draft-rosen MVPNs with service provider tunnels operating in SSM mode start by sending all multicast traffic over a default MDT, as described in section 7 of Internet draft draft-rosen-vpn-mcast-07.txt. This default mapping results in the delivery of packets to each provider edge (PE) router attached to the provider router even if the PE router has no receivers for the multicast group in that VPN. Each PE router processes the encapsulated VPN traffic even if the multicast packets are then discarded.

A data MDT, as described in the next section, solves the problem of routers flooding unnecessary multicast information to PE routers that have no interested receivers for a particular VPN multicast group.

Copyright © 2009, Juniper Networks, Inc. All rights reserved. Trademark Notice.