Multicast Capability

An increasingly popular design is to use two multicast models on the enterprise network:

• Any Source Multicast (ASM) Originally introduced in 1990, ASM is a legacy form of Source-Specific Multicast (SSM) in which the host cannot specify the source it wants.

  The standard protocol set in support of ASM is IGMPv2 or IGMPv3.

• SSM Used to replicate one-to-many traffic streams containing audio, video, and software distribution.

  This requires that the network be able to interface with a service provider network natively with Protocol-Independent Multicast (PIM) for multicast. In this case, interfaces within the enterprise network are configured with PIM sparse-dense mode. All multicast groups carrying data operate in sparse mode, and the Auto-RP group (for distribution of PIM rendezvous point [RP] information) operates in dense mode. In the case that per-VPN limits are set up for multicast group counts or source counts, the enterprise requires SPs to be able to provision for up to 3000 potential source and group (S,G) entries as a typical figure for a large corporate network.

The optimum solution from an enterprise perspective is for the provider to support multicast VPN (MVPN) to obviate the need for the enterprise to create tunnels for the multicast traffic itself. Here are two typical questions to pose to providers:

• MVPN capability Do you support MVPN functionality such that the enterprise can use native PIM sparse mode (PIM-SM) to interface with your network?

• MVPN limits Do you configure a maximum number of multicast groups or source and group entries per VPN? Can you support up to 3000 (S,G) entries?