On 2011-07-17 20.10, Bob Armstrong wrote: The term segment is used because each node that runs the bridge program does filter packets that should stay local. Ah, so the bridge program is not really a bridge (at least not in the way I use the word). Usually I think of a bridging two networks as meaning to copy all traffic from network A to network B and vice versa. If the box or program does something smart about deciding which traffic should go where, then it's a "router" (or at least a "switch"). Hans gives the bridge program too much credit. :-) How does the bridge program decide what DECnet messages to bridge and what to drop? It only have one small optimization, in the same vein as a switch. If it knows the destination (have seen traffic from it previously), it will only propagate traffic to that other end if it is directed traffic. A router would be something very different, and way more clever. But a router would actually be a very nice thing to implement. If anyone feel like it, I'd be happy to help. The difference between a switch and my bridge program is mostly in that the bridge program works using UDP as a carrier for remote endpoints, as well as interfacing to local ethernets. It can also do some traffic throttling, but unlike a switch, it does not do something like STP, nor do it do any kind of ethernet autonegotiation. It does not really play with ethernet on a low enough level for that. Johnny