16 IntroductionStatic MAC EntriesUser defined static MAC entries are stored in the Bridging Table.For more information, see "Configuring Address Tables" on page 295.VLAN-aware MAC-based SwitchingPackets arriving from an unknown source address are sent to the microprocessor, where the sourceaddresses are added to the Hardware Table. Packets addressed to or from this address are more efficientlyforwarded using the Hardware Table.MAC Multicast SupportMulticast service is a limited broadcast service, which allows one-to-many and many-to-manyconnections for information distribution. Layer 2 Multicast service is where a single frame is addressed toa specific Multicast address, from where copies of the frame are transmitted to the relevant ports. IGMPSnooping is supported, including IGMP Querier which simulates the behavior of a multicast router,allowing snooping of the layer 2 multicast domain even though there is no multicast router. WhenMulticast groups are statically enabled, you can set the destination port of registered groups, as well asdefine the behavior of unregistered multicast frames.For more information, see "Multicast Forwarding Support" on page 355.Layer 2 FeaturesIGMP SnoopingInternet Group Membership Protocol (IGMP) Snooping examines IGMP frame contents, when they areforwarded by the device from work stations to an upstream Multicast router. From the frame, the deviceidentifies work stations configured for Multicast sessions, and which Multicast routers are sendingMulticast frames.For more information, see "IGMP Snooping" on page 366.Port MirroringPort mirroring monitors and mirrors network traffic by forwarding copies of incoming and outgoingpackets from a monitored port to a monitoring port. Users specify which target port receives copies of alltraffic passing through a specified source port.For more information, see "Defining Port Mirroring Sessions" on page 292.Broadcast Storm ControlStorm Control enables limiting the amount of Multicast and Broadcast frames accepted and forwardedby the device.When Layer 2 frames are forwarded, Broadcast and Multicast frames are flooded to all ports on therelevant VLAN. This occupies bandwidth, and loads all nodes connected on all ports.For more information, see "Enabling Storm Control" on page 289.
