Comms for multiple nodes.

[MuntyScruntfundle]

I need a socket server/client app which is a little unusual and I'm struggling to get my head around how it would work.

I have 128 nodes, all mini board pi Raspians, 8 stacks of 16 pis. Within each 2x stacks are 16 fan controllers. If a pi gets hot it needs to send a message to a controller to turn on the fan. The fan controller pis also need to be clients and need the ability to turn the fan on. I hope this is making sense.

I've had this working almost perfectly with a serial token ring, but now and then I get a rogue serial corruption that breaks the loop.

So, I'm looking for a socket server/client app to do the same. However, each pi needs to be a server and a client with the ability to accept messages from any other pi, and the ability to send to any other pi.

So an app with a server and client on separate threads seems feasible, but it boggles my head a little. Or can anyone think of a much simpler idea?

Many thanks.

[Larz60+]

why not use some solid state relays that allow high current through for running the fan?
Then you can do it all with one pi that will never get hot!