What is IGMP and Do I Really Need It?

IGMP is what gives a Jedi his power. It’s an energy
field created by all living things. It surrounds us and
penetrates us; it binds the galaxy together.
— Jedi Master Yoda, paraphrased

OK, maybe that’s a bit of an exaggeration. But IGMP really is the engine that drives an Audio (or video) Over IP system. It’s the traffic cop. It’s the librarian. It’s the facilitator and the repairman. We say that the ethernet switch system is the heart of your WheatNet-IP system. Well IGMP is the heart of your ethernet switch system.

IGMP stands for Internet Group Management Protocol. It is the communications protocol used by routers on your network to handle multicast groups. Multicast groups ensure that your audio (which, after all, is distributed as multicast network data) goes to the places in your AoIP network where it is needed, and just as importantly, doesn’t go to the places where it isn’t needed.

There is an enormous amount of data on an AoIP network. The more WheatNet-IP Blades you have on your network, the more data exists on the network. Without IGMP, all the audio data in your system would have to go to every single device that is connected to your network. Every Blade, every surface, every talent station and computer would receive tons of data that it doesn’t need or care about, and port flooding would occur. With flooding comes packet loss, and with packet loss comes audio dropouts, missed or sluggish meters/control and galactic Chaos.

Wheatstone specifies certain IGMP settings that must be included in your ethernet switches in order for there to be calm in your audio universe. With these settings, your system will have an IGMP “querier,” which will keep track of multicast groups. These groups control which devices should receive which streams of multicast data. This ensures that no device, even those that only have 10/100 ethernet adapters, receives more data than it can handle.

If you are having trouble with sluggishness or certain other kinds of problems, Wheatstone may ask you to send us your switch configurations and, on occasion, we may ask you to Wireshark a port on your system. This will help us help you to determine if your network is configured correctly. The latest version of WheatNet-IP Navigator has a built-in tool to help you determine if your blades are seeing IGMP messages and at what intervals.

But this is why we talk so much about what kind of Ethernet switch you have and how it's configured. Not every switch has IGMP support, or it may only be able to recognize the traffic but not manage it. Plus, most switches that have the right features don't have IGMP enabled by default. It's important to stick to Approved Ethernet Switches for WheatNet-IP and configure them to our specifications to keep your system running smoothly.

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