Allied Telesis AT-FS970M Series - Manual (Page 604)

Chapter 40: IGMP Snooping Querier
604
network with IGMP snooping enabled and IGMP querier disabled
determines the standby querier and then the second standby querier by
comparing their IP addresses.
The following example consists of a LAN with three switches. See
Figure 118. IGMP snooping is enabled on all three switches. However,
IGMP snooping querier is enabled on switches 1 and 3. Switch 2
determines that switch 1 has the lowest IP routing address and forwards
all multicast packets to switch 1, making switch 1 the active querier.
Switch 3 becomes the standby querier in case switch 1 stops transmitting
query packets.
Note
Switches 1 and 3 are only sending queriers. Neither switch detects
nor displays an opposing querier.
Figure 118. IGMP Snooping Querier with Two Queriers
Table 63 lists the switch settings that are illustrated in Figure 118.
Table 63. IGMP Snooping Querier with Two Queriers
Switch
Routing
Address
IGMP
Snooping
IGMP
Snooping
Querier
Querier
Status
1 149.123.48 .2 Enabled Enabled Active