Allied Telesis AT-S39 - Manual (Page 145)

AT-S39 User’s Guide
145
Without IGMP snooping, a switch would have to flood multicast packets
out all of its ports, except the port on which it received the packet. Such
flooding of packets can negatively impact switch and network
performance.
The AT-8024, AT-8024GB, and AT-8026FC switches support both IGMP
Version 1 and Version 2. The switches maintain their multicast groups
through an adjustable time-out value, which controls how frequently
they expect to see reports from end nodes that want to remain members
of multicast groups, and by processing leave requests.
Note
By default, IGMP snooping is disabled on the switch.