IGMP - ip igmp snooping querier command
When configuring an IGMP snooping querier on a switch when there is no multicast router, we can use the ip igmp snooping querier command. Note that this command enables the querier feature on the local router.
Part of the process involved is for the local device to choose a particular IPv4 address to use as the source of the querier. This can be specified using additional keywords of this command like so:
ip igmp snooping querier address 192.168.1.1
This command enables the IGMP snooping querier feature on the device, and specifies that the source IP address for the querier. If no address is specified, then the following process is followed to determine the source address:
When enabled, the IGMP snooping querier uses the IP address of the VLAN interface as the query source address.
If there is no IP address configured on the VLAN interface, the IGMP snooping querier tries to use the configured global IP address for the IGMP querier. If there is no global IP address specified, the IGMP querier tries to use the VLAN switch virtual interface (SVI) IP address (if one exists). If there is no SVI IP address, the device uses the first available IP address configured on the device. The first IP address available appears in the output of the show ip interface privileged EXEC command.
If no IP address is configured, the querier will fail.
Links:
https://forum.networklessons.com/t/igmp-snooping-without-router/1342/78?u=lagapidis
https://networklessons.com/cisco/ccie-routing-switching/igmp-snooping-without-router/