A bridge (hw) maintains a list of mac addresses it sees at each port. A bridge will never forward a packet with a destination address on that list. The bridge ( program) learns which mac addresses live behibd what port and thus knows what traffic to forward and what not. Broadcst, multicast traffic is always forwarded. The only difference between a DEBET and the program is that the program ignores all other protocols Verzonden vanaf mijn draadloze BlackBerry -toestel -----Original Message----- From: "Bob Armstrong" <bob at jfcl.com> Sender: owner-hecnet at Update.UU.SE Date: Sun, 17 Jul 2011 11:10:11 To: <hecnet at Update.UU.SE> Reply-To: hecnet at Update.UU.SESubject: RE: [HECnet] DECnet et al 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"). How does the bridge program decide what DECnet messages to bridge and what to drop? Thanks, Bob