Allied Telesis AT-S63 - Manual (Page 230)

Chapter 20: Internet Group Management Protocol Snooping Querier
230 Section III: Snooping Protocols
Guidelines
The guidelines for IGMP snooping querier are listed here:
 The network can have only one LAN.
 There cannot be any multicast routers.
 IGMP snooping must be enabled on the switch.
 IGMP snooping querier should be enabled on just one switch. Other
switches in the LAN should use IGMP snooping.
 IGMP snooping querier must be applied to the VLAN on which the
queries are to be sent.
 The VLAN must be assigned a routing interface with an IP address
from the same network as the host nodes and the source node of the
multicast packets. The switch adds the IP address to the queries as
the source address.
 The identifier of the routing interface must be 0 (e.g., VLAN1-0,
VLAN2-0, etc.).
 If you want to add or remove ports from the VLAN after you have
assigned IGMP snooping querier to it, you must remove IGMP
snooping querier and reapply it after you have modified the VLAN.
 The switch supports both IGMP version 1 and version 2. The switch
normally sends just version 2 messages. If it receives a version 1
message, it sends version 1 messages on all of the ports. If the switch
does not receive any further version 1 messages for 400 seconds, the
switch reverts to sending version 2 messages.
 If the switch receives a query either from a multicast router or from
another switch with IGMP snooping querier, it suspends IGMP
snooping querier and sends no further queries for 225 seconds. If the
switch does not receive any further queriers, it reactivates the feature
and resumes sending queries.
 IGMP snooping querier is supported on the base ports and the SFP
and XFP modules.
 Disabling IGMP snooping also disables IGMP snooping querier and
removes it from its interface assignment.