Hack the Route Start free Open app Switches and VLANs
IGMP snooping
A switch reading its devices' IGMP to send each multicast group only out of the ports that joined it.
A plain switch floods multicast to every port, like broadcast. A snooping switch listens to the IGMP reports
and leaves passing through it and keeps a multicast database: which ports have members of which group. A group's
traffic then goes only to those ports, plus towards multicast routers. Snooping depends on a querier: without regular
queries the entries age out. On Linux, bridge mdb show is the table.