Light boards these days are just computers with some domain-specific IO. Tired of our ancient ETC Expression console, my colleagues and I wanted to start using ETC's new Nomad control software on our laptops. Our venue's dimmers only understood ETCNet2, while Nomad could only speak the newer ETCNet3 (and a few other open standards we couldn't use). Attempting a software upgrade on the dimmers themselves seemed incredibly risky. To bring Nomad's output to DMX would have required an additional $500 hardware purchase on top of the already-not-cheap software license.
On the message boards, I discovered a strange fact. The ETC-branded DMXNet2 interfaces we owned were actually white-label manufactured by a company called Pathport. Pathport boxes spoke a much wider array of protocols using the same hardware. These things handled firmware updates by flashing themselves with whatever was served to them over BOOTP. Pathport firmware images were free to download straight from the manufacturer.
Net3->Net2 was too much to ask for, but they could do ArtNet (an open standard) to DMX. Nomad could also emit ArtNet. So I flashed and configured one node to operate as ArtNet -> DMX, and plugged it into another node configured for DMX -> Net2.
So now, locked in a closet, there is a very strange loop of switch -> hacked ETC box -> normal ETC box -> switch which seems bizarrely redundant, but actually makes the world go 'round. And I could run lights and sound from any network drop in the building.