Multicast L3VPN Overview
The Junos Space Connectivity Services Director application uses Multiprotocol-BGP (MBGP) Multicast L3VPNs (MVPN) to implement MVPNs because it is simpler. This method does not require a service provider to configure multicast in its provider backbone to connect PE routers.
For the control plane, MBGP MVPN uses the intra-autonomous system (AS) next-generation BGP. The data plane is configured with Protocol Independent Multicast (PIM) sparse mode. Connectivity Services Director maintains PIM state information using the same architecture that is used for unicast VPNs.
The MBGP MVPN method avoids potential control and data plane scaling problems that can occur with the requirement to maintain two routing and forwarding mechanisms, one for VPN unicast and one for VPN multicast.
The Connectivity Services Director application addresses aspects of published standards as follows:
IP service, as defined by RFC 4364, is supported to enable service providers to implement IP multicast for IP services.
The architecture defined by RFC 4364 for unicast VPNs is supported to enable service providers to configure BGP for the control plane between PE routers.
Unicast with extensions for intra-Autonomous System (AS) and inter-AS communication, as defined by RFC 4364, is supported.
For MVPNs, Connectivity Services Director enables you to configure two site sets, a sender site set and a receiver site set. Site sets have the following properties:
Hosts within a sender site can originate multicast traffic for receivers in a receiver site set.
Receivers outside the receiver site set should not be able to receive traffic sent from the sender site.
Hosts within the receiver site set can receive multicast traffic originated from any host in the sender site set.
Hosts within the receiver site set should not be able to receive multicast traffic originated from any host that is not in the sender site set.
A host can be in both the sender site set and the receiver site set. Therefore, such a host can both originate and receive multicast traffic. For example, the sender site set could be the same as the receiver site set. In this case, all hosts could both originate and receive multicast traffic from one another.
Administrative policies define an MBGP MVPN. The policies define both the sender site set and receiver site set. Customers establish the policies but the policies are implemented by service providers, which use the existing BGP and MPLS VPN infrastructure.