IGMP Snooping 315Figure 81 Multicast packet transmission when IGMP Snooping runsIGMP Snooping TerminologyTable 308 explains switching terminology relevant to IGMP Snooping.The Switch 5500 runs IGMP Snooping to listen to the IGMP messages and map thehost and its ports to the corresponding multicast group address. To implement IGMPSnooping, the switch processes different IGMP messages as shown in Figure 82.Table 308 Switching Terminology relevant to IGMP SnoopingTerm MeaningRouter Port The port of the switch, directly connected to the multicastrouter.Multicast member port The port connected to the multicast member. The multicastmember refers to a host that joined a multicast group.MAC multicast group The multicast group is identified with MAC multicast addressand maintained by the Switch 5500.Router port aging time Time set on the router port aging timer. If the switch has notreceived any IGMP general query messages before the timertimes out, it is no longer considered a router port.Multicast group member portaging timeWhen a port joins an IP multicast group, the aging timer of theport will begin timing. If the switch has not received any IGMPreport messages before the timer times out, it transmits IGMPspecific query message to the port.Maximum response time When the switch transmits IGMP specific query message to themulticast member port, the Switch 5500 starts a responsetimer, which times before the response to the query. If theswitch has not received any IGMP report message before thetimer times out, it will remove the port from the multicastmember portsInternet / IntranetVideo streamVOD ServerLayer 2 Ethernet SwitchVideo streamMulticast group member Non-multicastgroup memberMulticast routerVideo stream Video streamVideo streamNon-multicastgroup memberSwitch 5500
