What role does the IGMP Querier have in a network?

The IGMP Querier plays a critical role in managing multicast traffic within a network. Specifically, its primary function is to maintain a list of multicast subscriptions from devices on the network. This involves sending queries at regular intervals to determine which multicast groups are being actively used and by which devices. When a device wants to join a multicast group, it sends an IGMP report, and the Querier keeps track of these subscriptions to ensure that multicast traffic is efficiently directed only to those devices that have expressed interest in receiving it.

This management of multicast traffic is essential for preventing unnecessary flooding of multicast packets to all devices on a network segment, which can lead to network congestion and degraded performance. In essence, the IGMP Querier helps optimize the use of network resources by ensuring that only the appropriate data is sent to devices that are actively listening for it.