Multicast protocols deliver packets from one source to multiple receivers. They
facilitate better bandwidth utilization and help to reduce the processing load on
hosts and routers, making them ideal for use in applications such as video and
audio conferencing, whiteboard tools, and stock distribution tickers.

The switch maintains a multicast forwarding table to make forwarding decisions
for packets that arrive with a multicast destination MAC address. When multicasts
are restricted only to specified ports, traffic is prevented from going to parts of the
network where there are no receivers. When a packet enters the switch, the
destination MAC address is combined with the VLAN ID and a search is performed
in the multicast forwarding table. If no match is found, then the packet is either
flooded to all ports in the VLAN or discarded, depending on the switch
configuration. If a match is found, the packet is forwarded only to the ports that are
members of that multicast group.