280 Configuring Device Informationw w w . d e l l . c o m | s u p p o r t . d e l l . c o m Layer 2 switching forwards Multicast packets to all relevant VLAN ports by default, treating thepacket as a Multicast transmission. While this is functional, in the sense that all relevantports/nodes receive a copy of the frame, it is potentially wasteful as ports/nodes may receiveirrelevant frames only needed by a subset of the ports of that VLAN. Multicast forwarding filtersenable 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 IGMPpackets to the CPU. The CPU analyzes the incoming packets and determines which ports are tojoin which Multicast groups, which ports have Multicast routers generating IGMP queries, andwhat routing protocols are forwarding packets and Multicast traffic. Ports requesting to join aspecific Multicast group issues an IGMP report specifying that Multicast group. This results in thecreation 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→GlobalParameters in the tree view.Figure 7-110. Multicast Global ParametersBridge Multicast Filtering — Enables or disables bridge Multicast filtering. Disabled is the defaultvalue.IGMP Snooping Status — Enables or disables IGMP Snooping on the device. Disabled is thedefault value.Enabling Bridge Multicast Filtering on the Device1 Open the Multicast Global Parameters page.2 Select Enable in the Bridge Multicast Filtering field.3 Click Apply Changes.
