Dell PowerConnect 7048P User Manual - Page 703

25 Configuring L2 Multicast Features This chapter describes the layer 2 multicast features on the PowerConnect 7000 Series switches. The features this chapter describes include bridge multicast filtering, Internet Group Management Protocol (IGMP) snooping, Multicast Listener Discovery (MLD) snooping, and Multicast VLAN Registration (MVR). The topics covered in this chapter include: • L2 Multicast Overview • Default L2 Multicast Values • Configuring L2 Multicast Features (Web) • Configuring L2 Multicast Features (CLI) • L2 Multicast Configuration Examples L2 Multicast Overview Multicast traffic is traffic from one source that has multiple destinations. The L2 multicast features on the switch help control network flooding of Ethernet multicast and IP multicast traffic by keeping track of multicast group membership. What Are the Multicast Bridging Features? The PowerConnect 7000 Series switches support bridge multicast filtering and bridge multicast forwarding. For Ethernet multicast traffic, the switch uses a database called the Layer 2 Multicast Forwarding Database (MFDB) to make forwarding decisions for packets that arrive with a multicast destination MAC address. By limiting multicasts to only certain ports in the switch, traffic is prevented from going to parts of the network where that traffic is unnecessary. When a packet enters the switch, the destination MAC address is combined with the VLAN ID, and a search is performed in the Layer 2 MFDB. If no match is found, then the packet is either flooded to all ports in the VLAN or Configuring L2 Multicast Features 703