MBGP MPLS Multicast VPN Sites

MBGP MVPNs employ the intra-autonomous system (AS) next-generation BGP control plane and Protocol Independent Multicast (PIM) sparse mode as the data plane.

The main characteristics of MBGP MVPNs are:

• They extend Layer 3 VPN service (RFC 4364) to support IP multicast for Layer 3 VPN service providers.
• They follow the same architecture as specified by RFC 4364 for unicast VPNs. Specifically, BGP is used as the provider edge (PE) router-to-PE router control plane for multicast VPN.
• They eliminate the requirement for the virtual router (VR) model (as specified in Internet draft draft-rosen-vpn-mcast, Multicast in MPLS/BGP VPNs) for multicast VPNs and the RFC 4364 model for unicast VPNs.
• They rely on RFC 4364-based unicast with extensions for intra-AS and inter-AS communication.

An MBGP MVPN defines two types of site sets, a sender site set and a receiver site set. These sites have the following properties:

• Hosts within the sender site set can originate multicast traffic for receivers in the receiver site set.
• Receivers outside the receiver site set should not be able to receive this traffic.
• Hosts within the receiver site set can receive multicast traffic originated by any host in the sender site set.
• Hosts within the receiver site set should not be able to receive multicast traffic originated by any host that is not in the sender site set.

A site can be in both the sender site set and the receiver site set, so hosts within such a site can both originate and receive multicast traffic. For example, the sender sites set could be the same as the receiver site set, in which case all sites could both originate and receive multicast traffic from one another.

Sites within a given MBGP MVPN might be within the same organization or in different organizations, which means that an MBGP MVPN can be either an intranet or an extranet. A given site can be in more than one MBGP MVPN, so MBGP MVPNs may overlap. Not all sites of a given MBGP MVPN have to be connected to the same service provider, meaning that an MBGP MVPN can span multiple service providers.

Another way to look at an MBGP MVPN is to say that an MBGP MVPN is defined by a set of administrative policies. These policies determine both the sender site set and the receiver site set. These policies are established by MBGP MVPN customers, but implemented by service providers using the existing BGP and MPLS VPN infrastructure.