Operation Manual – MulticastH3C S3100 Series Ethernet Switches Chapter 2 IGMP Snooping Configuration2-22.1.2 Basic Concepts in IGMP SnoopingI. IGMP Snooping related portsAs shown in Figure 2-2, Router A connects to the multicast source, IGMP Snoopingruns on Switch A and Switch B, Host A and Host C are receiver hosts (namely, multicastgroup members).Router A Switch ASwitch BEth1/0/1 Eth1/0/2Eth1/0/3Eth1/0/1Eth1/0/2ReceiverReceiverHost AHost BHost CHost DSourceMulticast packetsRouter portMember portFigure 2-2 IGMP Snooping related portsPorts involved in IGMP Snooping, as shown in Figure 2-2, are described as follows:z Router port: A router port is a port on the Layer 3 multicast device (DR or IGMPquerier) side of the Ethernet switch. In the figure, Ethernet 1/0/1 of Switch A andEthernet 1/0/1 of Switch B are router ports. A switch registers all its local routerports in its router port list.z Member port: A member port is a port on the multicast group member side of theEthernet switch. In the figure, Ethernet 1/0/2 and Ethernet 1/0/3 of Switch A andEthernet 1/0/2 of Switch B are member ports. The switch records all member portson the local device in the IGMP Snooping forwarding table.II. Port aging timers in IGMP Snooping and related messages and actionsTable 2-1 Port aging timers in IGMP Snooping and related messages and actionsTimer Description Messagebefore expiryAction afterexpiryRouter portaging timerFor each router port, theswitch sets a timerinitialized to the agingtime of the route portIGMP generalquery or PIMhelloThe switchremoves this portfrom its router portlist
