What is IGMP Snooping and how does it work?
Ans: IGMP Snooping provides a method for intelligent, targeted forwarding of multicast packets within a broadcast domain. By snooping IGMP registration information, a distribution list of workstations is formed that determines which end-stations will receive packets with a specific multicast address. Non-IGMP switches treat IP multicast traffic in the same manner as broadcast traffic — namely by forwarding frames received on one interface to all other interfaces. This may create excessive traffic on the network and degrade the performance of hosts attached to the switches. Every frame received by each host generates an interrupt that the host must process, robbing cycles that might instead be used by applications. The larger the network grows; the greater the impact of this extraneous multicast traffic. On the diagrams above and below we see that, by selecting IGMP snooping on the switch, only hosts that are group receivers actually receive multicast traffic.
