H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 174)

24-2
Figure 24-1 Multicast forwarding before and after IGMP snooping runs
Multicast packet transmission
without IGMP Snooping
Source
Multicast router
Host A
Receiver
Host B
Host C
Receiver
Multicast packets
Layer 2 switch
Multicast packet transmission
when IGMP Snooping runs
Source
Multicast router
Host A
Receiver
Host B
Host C
Receiver
Layer 2 switch
IGMP Snooping Related Ports
As shown in Figure 24-2 , Router A connects to the multicast source, IGMP snooping runs on Switch A
and Switch B, Host A and Host C are receiver hosts (namely, multicast group members).
Figure 24-2 IGMP snooping related ports
Router A Switch A
Switch B
Eth1/1 Eth1/2
Eth1/3
Eth1/1
Eth1/2
Receiver
Receiver
Host A
Host B
Host C
Host D
Source
Multicast packets
Router port
Member port
IGMP snooping related ports include:
Router port: A router port is a port on an Ethernet switch that leads the switch towards the Layer 3
multicast device (DR or IGMP querier). In the figure, Ethernet 1/1 of Switch A and Ethernet 1/1 of
Switch B are router ports. A switch registers all its local router ports in its router port list.
Member port: On an Ethernet switch, a member port (also known as multicast group member port)
connects the switch to a multicast group member. In the figure, Ethernet 1/2 and Ethernet 1/3 of Switch