US Patent 10020952 PIM relay mode in computer networks

Techniques are described for operating a network switch device associated with a virtual layer two (L2) network instance according to a protocol independent multicast (PIM) relay mode. The PIM relay mode enables the network switch device to receive a PIM control message, i.e., a PIM join and/or prune request, for a multicast group on a downstream port of the network switch device associated with a virtual L2 network instance, determine an upstream neighbor port of the network switch device associated with the instance, and relay the PIM control message on the upstream neighbor port of the network switch device without flooding the PIM control message on all ports of the switch device associated with the instance. In the PIM relay mode, the network switch device avoids triggering join suppression in downstream PIM neighbor devices with receivers, and avoids maintaining upstream states and setting a PIM periodic message timer.