IGMP - Snooping Querier

An IGMP Snooping Querier is a network function involved in the management of multicast traffic when using IGMP in conjunction with IGMP snooping on a switch.

In order for IGMP snooping to operate efficiently, a multicast router must be present on the network to perform the role of the IGMP querier. However, in networks where there is no multicast router or for certain VLANs that don't have a multicast router, an IGMP snooping querier can be used. This querier is usually a functionality within the network switch that generates IGMP queries on a timed interval. The purpose of these queries is to solicit IGMP Membership Reports from hosts, to understand which multicast groups are needed on which ports. This ensures that multicast traffic continues to be delivered efficiently in the absence of a multicast router.

IGMP Snooping Querier is a function that can be enabled on network switches to maintain efficient multicast traffic distribution in environments lacking a dedicated multicast router. It helps in managing multicast memberships by soliciting reports from hosts, thereby allowing the switch to make informed decisions about where to forward multicast traffic.