Some thoughts and ideas for Art-Net, part 3
It's about time I wrap this up - and I've saved my favourite gripe for last..
Let's talk IP
One of the basic concepts of IP networks is that each device has got a unique address, an "IP address". Without IP addresses, switches and routers in the network wouldn't know in which direction to pass on messages - in fact, devices wouldn't even be able to tell whether messages were intended for them or not. This is why your typical office environment is equipped with a DHCP server that assigns IP addresses automatically to any device you connect to the network.
In a show environment network you will want every device to have a fixed IP address though, so not to have to wait for the DHCP server to assign addresses on power-up and/or risk a device changing its address. The catch then of course is that in order to manually assign an IP address to a device it needs to have a configuration panel of some sort. For some devices that isn't an option, so to solve the problem Art-Net comes with an auto-configuration scheme which dictates that devices should default to a 2.x.y.z IP address along with a scheme for how to assign the x.y.z numbers in a clever manner.
So that's why I need to be on a 2.x.y.z subnet?
Yes - but only if you are working with devices of the kind mentioned above. If you're in the office, running an offline version of your show control system and a visualizer, then there is no need at all. In fact, if you're in an office environment then the last thing you may want to do is add a fixed 2.x.y.z IP address to your computer(s) to "comply with Art-Net".
All Art-Net messages work perfectly fine on any IP subnet. Any computer software that requires your computer to be configured to a 2.x.y.z subnet in order to transmit or receive Art-Net has been poorly designed and should be mended - and particularly those that insist on sending Art-Net data to the 2.x.y.z network on a machine that doesn't even have an IP address on that network. These should burn in a very hot and particularly unpleasant place.
If despite all this you believe you have good reasons for adding fixed Art-Net IP addresses to your computers and/or consoles in addition to your existing DHCP IP addresses then make sure you are armed with some very solid knowledge of IP networking.