The DIX spec says that hardware addresses ( the ones you put in the simh configuration file starting with 08-00-2B) must be unique . Verzonden vanaf mijn BlackBerry 10-smartphone. Origineel bericht Van: Jean-Yves Bernier Verzonden: zaterdag 24 mei 2014 23:14 Aan: hecnet at Update.UU.SE Beantwoorden: hecnet at Update.UU.SE Onderwerp: Re: [HECnet] Same MAC address on different nodes At 10:21 PM +0200 24/5/14, Johnny Billquist wrote: So "Physical" is not "Hardware", and there is no need to SET XQ MAC. I tried and it maked no change. Right. Since your machine will set a different MAC address anyway, at start, when you enable DECnet. The physical address is whatever you set in simh before starting. It have no actual relevance once DECnet starts. If you were to run something else, which did not use DECnet (such as Unix), the address you set in simh will be the actual MAC address used, since IP do not change the MAC address of interfaces. No need. You mean "the Hardware address is whatever you set in simh before starting". CEX will set it to "Physical address" (in DECNET parlance) which is AA-00-04-00-(1024 x area + node). The MAC address is AA-00-04-00-01-28 for DECNET and 08-00-2B-AA-BB-CC for Linux. So, a NIC may have different MAC addresses depending of the network stack running. Am I right here? Really hard to give a good explanation on why without having good access to all parts of the setup to be able to test and examine things. Well, my system is working 99%, that's not so bad :) -- Jean-Yves Bernier