I asked the engineers behind the networking component of the HDMI over IP solution to comment about this recommendation and they don't really want to publicly give out a whole lot of details/secrets away about how we are doing some of this at this time. Please just accept that we recommend you choose a Managed Switch that does support IGMP. You are certainly welcome to try the HDMI over IP solution on a Managed Switch that does not support IGMP, we just don't recommend it. The switch we used during the "proof of concept" phase was the Cisco Catalyst 2960 24LT-L. About 1/4 of the way down the specifications posted on the Cisco website at
Cisco Catalyst 2960 Switches with LAN Base Software [Cisco Catalyst 2960 Series Switches] - Cisco Systems you will see the following under the heading Superior Manageability:
Do you have a specific objection to using a Managed Switch that supports IGMP? If you have a business opportunity in mind that justifies a "need to know more", please send me a PM. I hope you can appreciate the need to keep some things about our technology confidential.