Amer Networks SS2GD8IP - Manual (Page 200)

Publication date:Dec., 2010
Revision B1 188
3-17.
Multicast
The function, is used to establish the multicast groups to forward the
multicast packet to the member ports, and, in nature, avoids 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 can not 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 supported 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 up in advance.
3-17-1. IGMP mode
Function name:
IGMP Mode Configuration
Function description:
IGMP mode enables the switch to issue IGMP function that you enable 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.
Fig. 3-163-0 IGMP Mode
Parameter description:
IGMP Mode:
To scroll the IGMP mode with “Disable” , “Proxy” or “Snooping”