3com WX3000 Manuel D’Utilisation
2-4
immediately delete the forwarding entry corresponding to that port from the forwarding table; instead, it
resets the aging timer of the member port.
Upon receiving the IGMP leave message from a host, the IGMP querier resolves from the message the
address of the multicast group that the host just left and sends an IGMP group-specific query to that
multicast group through the port that received the leave message. Upon receiving the IGMP
group-specific query, a device forwards it through all the router ports in the VLAN and all member ports
of that multicast group, and performs the following to the receiving port:
z
If any IGMP report in response to the group-specific query arrives to the member port before its
aging timer expires, this means that some other members of that multicast group still exist under
that port: the device resets the aging timer of the member port.
z
If no IGMP report in response to the group-specific query arrives to the member port before its
aging timer expires as a response to the IGMP group-specific query, this means that no members
of that multicast group still exist under the port: the device deletes the forwarding entry
corresponding to the port from the forwarding table when the aging timer expires.
After a device enables IGMP Snooping, when it receives the IGMP leave message sent by a host in a
multicast group, it judges whether the multicast group exists automatically. If the multicast group does
not exist, the device drops this IGMP leave message.
IGMP Snooping Configuration
IGMP Snooping Configuration Task List
Complete the following tasks to configure IGMP Snooping:
Operation
Remarks
Required
Optional
Optional
Optional
Optional
Optional
Optional
Optional
Optional
Optional
Optional