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3-5 IGMP Snooping
3-5.1 Basic
Configuration
The function is used to establish the multicast groups to forward the multicast
packet to the member ports, and in nature, to avoid wasting the bandwidth while IP
multicast packets are running over the network. This is because a switch that does
not support IGMP or IGMP Snooping cannot tell the multicast packet from the
broadcast packet, so it can only treat them all as the broadcast packet. Without
IGMP Snooping, the multicast packet forwarding function is plain and nothing is
different from broadcast packet.
A switch that supports IGMP Snooping with the functions of query, report and leave
(a type of packet exchanged between IP Multicast Router/Switch and IP Multicast
Host) can update the information of the Multicast table when a member (port) joins
or leaves an IP multicast destination address. With this function, once a switch
receives an IP multicast packet, it will forward the packet to the members who
joined in a specified IP multicast group before.
The packets will be discarded by the IGMP Snooping if the user transmits multicast
packets to the multicast group that had not been built in advance. The IGMP mode
enables the switch to issue IGMP functions (IGMP proxy or snooping) on the switch,
which connects to a router closer to the root of the tree. This interface is the
upstream interface. The router on the upstream interface should be running IGMP.
The section describes how to set the basic IGMP snooping on the switch, which
connects to a router closer to the root of the tree. This interface is the upstream
interface. The router on the upstream interface should be running IGMP.
Web Interface
To configure the IGMP Snooping parameters in the web interface:
1.
Click Configuration, IGMP Snooping, then Basic Configuration.
2.
Evoke to enable or disable a specific global configuration.
3.
Evoke which port you want to become a Router Port, or enable/disable the
Fast Leave function.
4.
Scroll to set the throttling parameter.
5.
Click “Apply” to save the setting.
6.
If you want to cancel the setting, click the reset button to revert back to
previously saved values.