1-3z Whenever mentioned in this document, a router port is a port on the switch that leads the switch toa Layer 3 multicast device, rather than a port on a router.z Unless otherwise specified, router/member ports mentioned in this document include static anddynamic ports.z An IGMP-snooping-enabled switch deems that all its ports on which IGMP general queries with thesource IP address other than 0.0.0.0 or PIM hello messages are received are dynamic router ports.Aging timers for dynamic ports in IGMP Snooping and related messages and actionsTable 1-1 Aging timers for dynamic ports in IGMP Snooping and related messages and actionsTimer Description Message beforeexpiry Action after expiryDynamic router portaging timerFor each dynamicrouter port, the switchsets a timer initializedto the dynamic routerport aging time.IGMP general query ofwhich the sourceaddress is not 0.0.0.0or PIM helloThe switch removesthis port from its routerport list.Dynamic member portaging timerWhen a portdynamically joins amulticast group, theswitch sets a timer forthe port, which isinitialized to thedynamic member portaging time.IGMP membershipreportThe switch removesthis port from the IGMPSnooping forwardingtable.The port aging mechanism of IGMP Snooping works only for dynamic ports; a static port will never ageout.How IGMP Snooping WorksA switch running IGMP Snooping performs different actions when it receives different IGMP messages,as follows:The description about adding or deleting a port in this section is only for a dynamic port. Static ports canbe added or deleted only through the corresponding configurations. For details, see Configuring StaticPorts.
