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Electronic Theatre Controls Inc

Net3 DMX/RDM Gateways stop responding to sACN when connected to switches using IGMPv3


I have a Net3 DMX/RDM Gateway, or a Response 4-port Gateway (Mk1) running v6.0.1 or earlier software plugged into a network switch, and after ~3 minutes it stops responding to changes in sACN, even though it indicates reception of sACN. Upon rebooting the Gateway it begins responding to sACN immediately, but fails again after a few minutes.

Explanation of Issue & Solution

There was a defect in all versions v6.0.1 or earlier in which IGMPv3 wasn't working properly in the underlying operating system of the Gateway. Thus when connected to any network switch configured to use IGMPv3, it fails to respond to IGMP queries, causing the switch to no longer send sACN data to the Gateway. The Gateway may continue to show receipt of sACN, however it's actually using data loss behavior to hold onto the last-received data.

This issue does not present when connected to a network switch with IGMP disabled, or a switch configured to use IGMPv2. Most often this issue will likely be seen when replacing older existing network infrastructure with new switches (such as a Cisco CBS350 shipped from ETC), since IGMPv3 may be enabled by default.

This defect was first resolved in v7.0.0 Gateway software, so the recommend solution is to update the affected Gateways to the latest code available: v7.1.0. Alternatively the switch can be changed to use IGMPv2, if supported.


Older Net3 One Port Gateways (Gateway Version 1 here) may exhibit this problem as of their latest software version 4.3.2. Using IGMPv2 should resolve the issue in this case.

NOTE: this problem does not affect Response Mk2 DMX Gateways.


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