There's a trick possible which I've once seen employed: take the 3 lower bytes of the IP-address and use that for the lower 3 bytes of the MAC address. Only requires a way for a device driver to know the IP address at boot-up time. And since IP addresses are unique, the MAC address is also unique. Rob

 

You get what you pay for..... Dave Ferguson Blandin Paper Company UPM-Kymmene DAVCO Automation

 

Johan, Upon re-reading my post and your reply, I see that I have been too terse and not explained well what I mean. I'm not saying that all the cards of a particular manufacturer would have the same address; I'm simply saying they don't follow the protocol of obtaining unique Ethernet MAC addresses from the IEEE. So while that manufacturer's cards will each have unique addresses, there is a possibility that there exists another card with that address. The Ethernet address field contains six bytes. The first three are the Vendor Address, the remaining three are the serial number for the interface. Thus, in a perfect world, each vendor would manufacture cards consisting of their ID and the unique serial number of that particular interface. For example, interfaces made by Honeywell start with 0x000062, interfaces made by Allen-Bradley start with 0x0000BC. But in the real world, some vendors do not register their addresses. While some are careful about which addresses they use, and avoid using other vendors' addresses, some are not; thus there is the possibility that two cards might have the same address. I am not (yet) familiar with the registration process for getting an Ethernet vendor ID from the IEEE. I am going to find out how difficult this is, and how much it costs. What I suspect is that it is sufficiently painful (either monetarily or administratively) that some manufacturers opt to not bother about it. I found this out when I purchased a $9.00 10baseT NIC that came with a utility to change the MAC ID, if the user so desired. Sorry to have caused the confusion. Regards, Willy Smith Numatics Costa Rica

 

The best way to change mac address is to use network cards that allow this function. They are hard to come by, but available if you look hard enough. One option is available at http://www.sdadapters.com

Another option is a software based option, there is a GNU project underway, but I forgot the name of it. If you search hard enough you will find it.