3com WX3000 Manuel D’Utilisation

 

2-2 

Figure 2-2 IGMP Snooping related ports 

Router A

Switch A

Switch B

Eth1/0/1

Eth1/0 /2

Eth 1/0/3

Eth 1/0/1

Eth1/0 /2

Host A

Host B

Host C

Host D

 Multicast packets

Router port

Member port

 

 

Ports involved in IGMP Snooping, as shown in 

, are described as follows:  

z 

Router port: A router port is a port on the Layer 3 multicast device (DR or IGMP querier) side of the 

device. In the figure, Ethernet 1/0/1 of Switch A and Ethernet 1/0/1 of Switch B are router ports. A 

device registers all its local router ports in its router port list.  

z 

Member port: A member port is a port on the multicast group member side of the device. In the 

figure, Ethernet 1/0/2 and Ethernet 1/0/3 of Switch A and Ethernet 1/0/2 of Switch B are member 

ports. A device records all member ports on the local device in the IGMP Snooping forwarding 

table.  

Table 2-1 Port aging timers in IGMP Snooping and related messages and actions  

expiry 

Router port aging timer 

For each router port, 
the device sets a timer 
initialized to the aging 
time of the route port  

IGMP general query or 
PIM hello  

The device removes 
this port from its router 
port list 

Member port aging 
timer  

When a port joins a 
multicast group, the 
device sets a timer for 
the port, which is 
initialized to the 
member port aging 
time  

IGMP membership 
report  

The device removes 
this port from the 
multicast group 
forwarding table  

 

A device running IGMP Snooping performs different actions when it receives different IGMP messages, 

as follows: