All Net3 DMX-RDM Gateways, Response Mk 1 Gateways, and Net 2/3 Nodes in Net3 mode running versions less than 6.0.1 require IGMP v2 if enabled from the managed switch. Gateways running 6.0.1+ can use IGMP v3.
Net2/3 Nodes in Net2 mode are not able to respond to IGMP requests. This can cause the IGMP querier to stop sending multicast traffic to the ports with Net2 products when they fail to respond to IGMP requests.
For this reason, IGMP should be disabled for Net2 systems that use EDMX such as Unison Legacy with CMEi processors.