Layer 2 switching forwards multicast packets to all relevant VLAN ports by default, treating the packet as a multicast packet. This type of traffic forwarding is

functional; however, irrelevant ports also receive multicast traffic, causing increased network traffic.

IGMP snooping eliminates unnecessary multicast traffic by examining IGMP frames while they are forwarded from stations to a multicast routers.

When IGMP snooping is globally enabled, the switching ASIC is programmed to forward all IGMP frames to the CPU. The CPU analyzes the incoming frames and

determines which ports want to join which Multicast groups, which ports have Multicast routers generating IGMP queries, and what Routing protocols are

forwarding packets and Multicast traffic. A port wishing to join a specific multicast group issues an IGMP report specifying that multicast group.

The Multicast Global Parameters page allows network managers to enable IGMP Snooping and Multicast Filtering in general on the device. To open the

Multicast Global Parameters page:

Click Switch > Multicast Support > Global Parameters in the Tree View. The Multicast Global Parameters page opens.

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