Learn how IGMP snooping, queriers, and multicast forwarding limit unnecessary traffic in Dante, AES67, and NDI environments.
Essential for maintaining stable IP media fabrics. For specific switch configurations, use our network switch configurator. Explore more broadcast engineering tools for IP video and media networking.
Technical review: 27 August 2026 · Confirm VLAN, querier, switch, and endpoint behavior in the target network.
IGMP Snooping limits multicast traffic to the ports that actually requested it. In media networks, that usually means fewer flooded ports, lower unnecessary load, and a much better chance of keeping Dante, AES67, and multicast NDI stable. The exact switch behavior still depends on vendor implementation and configuration.
In a standard IT network, data is usually transferred via Unicast—a direct one-to-one conversation between a sender and a receiver. But in a broadcast environment, you often need to send one camera's video feed to five different monitors, or one microphone's audio channel to three different mixing consoles simultaneously.
Sending five separate Unicast streams of the same 150 Mbps NDI video feed can overwhelm a source or uplink quickly. The solution is Multicast. The sender transmits a single stream to a specific group address, and receivers join that group when they need the traffic.
However, unmanaged or poorly configured switches may still flood multicast traffic across too many ports. That is the operational problem IGMP Snooping is trying to solve.
To prevent multicast flooding, managed switches use IGMP Snooping (Internet Group Management Protocol).
When IGMP Snooping is enabled, the switch actively "listens" (snoops) on the conversations between the devices to see who is requesting to join or leave a Multicast group. The switch builds an internal roadmap—a Multicast forwarding database.
IGMP Snooping by itself is a passive feature. The switch only listens to "Join" commands. But what happens if a device is restarted, or the switch rebooted? The switch forgets who wants what, and the Multicast stream stops routing.
This is why an IGMP Querier is usually required in practical AV multicast designs. The Querier is an active service that periodically checks which devices still want each multicast group.
The connected devices respond with their membership reports, keeping the switch's internal map updated. In a multi-switch AV network, you must ensure that only one single switch is elected as the active IGMP Querier for a given VLAN, usually the Core or highest-capacity router in the topology.
Dante networks, and some AES67 deployments, often rely on multicast flows for discovery, clocking support traffic, or specific audio subscriptions. A misconfigured IGMP topology can increase unnecessary load, which makes timing-sensitive traffic harder to protect with QoS. If that sounds familiar, read the PTP Clocking Guide next.
For high-bandwidth NDI, the stakes are often higher because the stream sizes are large enough to consume meaningful link capacity quickly. A single NDI High Bandwidth 1080p60 stream is often in the rough 125 Mbps range. (Read the NDI bandwidth guide.) Multicasting several of those streams on a small 1GbE network without a working querier or sensible VLAN design can create dropped frames and unstable monitoring paths.