3com S7906E 설치 설명서

 

1-4 

A 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 can 

be added or deleted only through the corresponding configurations. For details, see 

. 

 

The IGMP querier periodically sends IGMP general queries to all hosts and routers (224.0.0.1) on the 

local subnet to find out whether active multicast group members exist on the subnet.  

Upon receiving an IGMP general query, the switch forwards it through all ports in the VLAN except the 

receiving port and performs the following to the receiving port:  

z 

If the receiving port is a dynamic router port existing in its router port list, the switch resets the aging 

timer of this dynamic router port.  

z 

If the receiving port is not a dynamic router port existing in its router port list, the switch adds it into 

its router port list and sets an aging timer for this dynamic router port.  

A host sends an IGMP report to the IGMP querier in the following circumstances:  

z 

Upon receiving an IGMP query, a multicast group member host responds with an IGMP report.  

z 

When intended to join a multicast group, a host sends an IGMP report to the IGMP querier to 

announce that it is interested in the multicast information addressed to that group.  

Upon receiving an IGMP report, the switch forwards it through all the router ports in the VLAN, resolves 

the address of the reported multicast group, and performs the following:  

z 

If no forwarding table entry exists for the reported group, the switch creates an entry, adds the port 

as a dynamic member port to the outgoing port list, and starts a member port aging timer for that 

port.  

z 

If a forwarding table entry exists for the reported group, but the port is not included in the outgoing 

port list for that group, the switch adds the port as a dynamic member port to the outgoing port list, 

and starts an aging timer for that port.  

z 

If a forwarding table entry exists for the reported group and the port is included in the outgoing port 

list, which means that this port is already a dynamic member port, the switch resets the aging timer 

for that port.