An extranet can be viewed as part of a company’s intranet that is extended to users outside the company. It has also been described as a “state of mind” in which a VPN is used as a way to do business with other companies as well as to sell products and content to customers and companies. An extranet is a VPN connecting the corporate site or sites to external business partners or suppliers to securely share part of a business’s information or operations among them.

The Multicast VPN Extranet Support feature enables service providers to distribute IP multicast content originated from one enterprise site to other enterprise sites. This feature enables service providers to offer the next generation of flexible extranet services, helping to enable business partnerships between different enterprise VPN customers. Using this feature, service providers can offer multicast extranet contracts to meet various business partnership requirements, including short-term, annual, and rolling contracts.

Earlier to Release 8.2(1), Cisco NX-OS multicast implementation, multicast traffic can flow only within the same virtual routing and forwarding (VRF). However, with the introduction of the Multicast Extranet feature, multicast receivers can exist in different VRFs from source in an enterprise network.

With multicast extranet, the reverse path forwarding (RPF) lookup for multicast route in the receiver VRF can be carried out in the source VRF, thereby allowing to return a valid RPF interface. This forms a source or RP tree from the receiver VRF to the source VRF, thus enabling the traffic that originated from the source VRF to be forwarded to the outgoing interface (OIF) in the receiver VRF.

The Multicast VPN Extranet Support feature can be used to solve such business problems as:

• Efficient content distribution between enterprises

• Efficient content distribution from service providers or content providers to their different enterprise VPN customers

Prior to the introduction of the Multicast VPN Extranet VRF Select feature, RPF lookups for a source address could be performed only in a single VRF, that is, in the VRF where Internet Group Management Protocol (IGMP) or PIM joins are received, in the VRF learned from BGP imported routes, or in the VRF specified in static mroutes (when RPF for an extranet MVPN is configured using static mroutes). In those cases, the source VRF is solely determined by the source address or the way the source address was learned.

The Multicast Extranet VRF Select feature provides the capability for RPF lookups to be performed to the same source address in different VRFs using the group address as the VRF selector. This feature enhances extranet MVPNs by enabling service providers to distribute content streams coming in from different MVPNs and redistributing them from there.

The Multicast VPN VRF Select feature is configured by creating group-based VRF selection policies. Group-based VRF selection policies are configured using the ip multicast rpf select command. The ip multicast rpf select command is used to configure RPF lookups originating in a receiver MVRF or in the global routing table to be resolved in a source MVRF or in the global routing table based on group address. Access Control Lists (ACLs) are used to define the groups to be applied to group-based VRF selection policies.

The figure illustrates an extranet MVPN topology with the Multicast VPN VRF Select feature configured. In this topology, (S, G1) and (S, G2) PIM joins originating from VPN-Green, the receiver VRF, are forwarded to PE1, the receiver PE. Based on the group-based VRF selection policies configured, PE1 sends the PIM joins to VPN-Red and VPN-Blue for groups G1 and G2, respectively.