Well thank you, those ideas will be used in the next round of testing today. Once its all over I'll put a completed module targeted for that (rare) kind of broken playground in CUFP :)
With a list of limitations of course... Update:
this change solved part of the problem and the code should run without issues on a hub, now it seems that the router is blocking gratuitous arp replies, directed or not. This will require more investigation but I suppose a simple hub instead of a router/switch would let those through.
One possible explanation that I would love anyone in the know to confirm or deny is the following:<br
Even though arp is stateless the router keeps tracks of arp requests and replies and will only let a reply through if it has been preceded by a request AND|OR is agreeing with its own arp table