Simple peer to peer network?

[Jim Brain]

Sellam wants to finish the 64 c64 cluster for the next VCF.  I've been 
researching ideas for communicating among the machines, and the best 
ideas point to using the two synchronous serial ports on the user port 
(low wire count, transfers at 250kbps).

But, I have grawn a complete blank on plans for a true peer to peer 
(token based or otherwise) networking protocol.  Everything I see is 
master/slave.  RS485 material talks about the hardware layer, but there 
is no detail on the protocol layer. 

I would think this would be a well researched and innovated area, low 
speed communication without a master node.  Anyone have any pointers for 
things to look into?

Jim