Dell PowerConnect 5424 User Manual page 356

The device supports:
• Forwarding L2 Multicast Packets — Enabled by default, and not configurable.
• The system supports Multicast filtering for 256 Multicast groups.
• Filtering L2 Multicast Packets — Enables forwarding of Layer 2 packets to interfaces. If Multicast
filtering is disabled, Multicast packets are flooded to all relevant ports.
To open the Multicast Support page, click Switch→ Multicast Support in the tree view.
Defining Multicast Global Parameters
Layer 2 switching forwards Multicast packets to all relevant VLAN ports by default, treating the packet as
a Multicast transmission. While this is functional, in the sense that all relevant ports/nodes receive a
copy of the frame, it is potentially wasteful as ports/nodes may receive irrelevant frames only needed by a
subset of the ports of that VLAN. Multicast forwarding filters enable forwarding of Layer 2 packets to
port subsets, defined in the Multicast filter database.
When IGMP snooping is enabled globally, the switching ASIC is programmed to forward all IGMP
packets to the CPU. The CPU analyzes the incoming packets and determines which ports are to join
which Multicast groups, which ports have Multicast routers generating IGMP queries, and what routing
protocols are forwarding packets and Multicast traffic. Ports requesting to join a specific Multicast group
issues an IGMP report specifying that Multicast group. This results in the creation of the Multicast
filtering database.
The Multicast Global Parameters page contains fields for enabling IGMP Snooping on the device.
To open the Multicast Global Parameters page, click Switch→ Multicast Support→ Global Parameters in
the tree view.
Figure 7-55. Multicast Global Parameters
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Configuring Device Information