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 switch 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 switch 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 switch deletes the forwarding entry
corresponding to the port from the forwarding table when the aging timer expires.
After an Ethernet switch 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 switch drops this IGMP leave message.
IGMP Snooping Configuration
The following table lists all the IGMP Snooping configuration tasks:
Table 2-2
IGMP Snooping configuration tasks
Operation
Remarks
Required
Configuring the Version of IGMP Snooping
Optional
Optional
Configuring Fast Leave Processing
Optional
Configuring a Multicast Group Filter
Optional
Configuring the Maximum Number of Multicast Groups on a Port
Optional
Optional
Suppressing Flooding of Unknown Multicast Traffic in a VLAN
Optional
Configuring Static Member Port for a Multicast Group
Optional
Configuring a Static Router Port
Optional
Configuring a Port as a Simulated Group Member
Optional
Configuring a VLAN Tag for Query Messages
Optional
Optional
Содержание Switch 4800G PWR 24-Port
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