Allied Telesis AT-S62 - Manual (Page 302)

Chapter 18: IGMP Snooping
Section II: Advanced Operations 302
network security by restricting the flow of multicast packets only to
those switch ports connected to host nodes.
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-8500 Series switch maintains its list of multicast groups through
an adjustable timeout value, which controls how frequently it expects to
see reports from end nodes that want to remain members of multicast
groups, and by processing leave requests.
Note
The default setting for IGMP snooping on the switch is disabled.