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I'm using w2k3 dhcp server, and I've reserved an IP adress for my laptop to facilitate port forwarding. I previously had a pure wired network, but I just added a WiFi router to this network for the obvious benefits of wireless, but I want to keep using the wired network in case I need more speed than the wireless part can deliver.

Of course I forgot that the wireless card of my laptop has it's own MAC address, and when I connect over WiFi to my network I get a different (from the reserved one) IP address. This is a problem because I can configure my port forwarding only for ip-addresses, not hostnames. So I absolutely need to have the same IP address given to my laptop by dhcp wether I'm using WiFi or a wired connection.

The big problem is that the DHCP server on w2k3 doesn't allow me to configure the same IP address for a different MAC.

Any thoughts on this?

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up vote 3 down vote accepted

You might be able to "clone" the wired NIC's MAC onto the wireless NIC. A fair number of NICs have drivers that expose this functionality under its "Advanced" tab for the NIC driver properties.

Just keep in mind, as with the DHCP reservation approach, you need to take care to not have both NICs on the LAN at the same time. With the duplicate MACs approach, it may cause more disruptive effects at the network switching level vs. a limited duplicate IP shutdown of the "offending" devices/hosts.

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So you're saying that as long as I keep only one NIC active on the same LAN at the same time, this won't give me any problems? – dvdvorle Aug 27 '11 at 17:32
You should be fine. You might have a better/quicker DHCP assignment experience by releasing the DHCP reservation first as you transition between the NICs. – user48838 Aug 27 '11 at 17:37
Apparently Windows 7 limits the MAC addresses assignable to wireless network adapters. I solved that by "cloning" the wireless NIC's MAC onto the wired instead. You were right about the releasing too. I'd even qualify releasing mandatory, since it didn't work otherwise. Thanks! – dvdvorle Aug 27 '11 at 17:55
Glad it worked out. The limitations may not be with Windows 7 as not all NIC drivers expose the functionality. – user48838 Aug 27 '11 at 18:58
Well, I meant the following: . My wired MAC address was not valid under those constraints (I did try ofc. Didn't work). – dvdvorle Aug 30 '11 at 12:42

If your server and client both support DHCP Client ID, that may is cleaner way than duplicating MAC addresses.

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A quick search on google didn't give me much info on "DHCP Client ID". Would you happen to know if this is supported on w2k3 + Win 7? – dvdvorle Aug 30 '11 at 12:43

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