Multicast over Fabric Connect cannot connect to a PIM router that is external to the SPB network.

When a receiver joins the SPB network for a specific group, the receiver must receive multicast streams in the neighboring multicast domains (PIM network). Similarly, a receiver in the neighboring multicast domain (PIM network) must receive multicast streams from sources in the SPB network. SPB-PIM Gateway (SPB-PIM GW) provides multicast inter-domain communication between an SPB network and a PIM network. SPB-PIM GW accomplishes this inter-domain communication across a special gateway VLAN. The gateway VLAN communicates with the PIM network through a subset of the full protocol messaging required for RFC 4601 compliance of a PIM interface, and translates the PIM network requirements into SPB language and vice versa.