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2.12 IGMP snoop function
The IGMP snoop function confirms the IGMP packet sent by source and transfers the multicast packet to the port
where receiver exists.
▪ Source
Terminal or multicast router connected to this device
▪ Port where receiver exists
Port where listener of multicast group address exists or the port where multicast router is connected
With the use of this function, unexpected multicast packets are not received by the terminal and the load
of terminal can be reduced.
In the IGMP snoop function of this device, versions 1, 2, 3 of the IGMP protocol are supported.
Conditions of the ports of this device, that are identified as port where multicast router is connected or
port where the listener exist are shown below.
Port
Multicast router port
It is recognized by the following conditions by the multicast router port settings (vlan <vlan_id>
igmpsnoop router).
▪ When auto is specified
When the IGMP Query packet is received, the concerned port is recognized as a multicast router
port.
▪ When yes<port_no > is specified
At the time of start up, port specified by the settings is recognized as multicast router port. Further,
as in the case where auto is specified, the port where IGMP Query packet is received is also
recognized as multicast router port.
Listener port
The port where the IGMP Membership Report packet is received is recognized as a listener port.
When the packet that has the address of multicast group in the address is received, this device transfers
that packet only to the multicast router port and the listener port.
Recognized conditions
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