Server 2003 DHCP giving same address to multiple computers.

[bingerthedog]

Here is our setup.
We have two 2003 Domain Controllers for only one subnet and one of them is setup to be the DHCP server. Everything seemed to be working fine until we added a Cisco Wireless LAN Controller. I setup the Wireless Controller so that we have two SSID's, one of them is for our private network which has access to all of our servers and is using MAC filtering and is password protected and the other is for Public access which is wide open but only has access to the internet. So on the DHCP server I have two scopes setup, one is on the 192.168.0 network and the other is one the 192.168.2 network. The 0 network gives addresses to wired clients and wireless clients on the private side and the 2 network gives addresses to wireless Public clients. The DHCP server has two NICs, one on the 0 network and one on the 2 network. I also enable RRAS so that the clients on the 2 network can access our default gateway. I also setup a V-Lan for the Public wireless clients and also setup DHCP a helper so that the clients dhcp request gets forwarded to the DHCP server. All of that seems to be working fine and clients are getting addresses from their desired network.

Now the problem.
Wireless clients and wired clients on the 0 network are getting assigned the same IP addresses and this of course is causing IP address conflicts. It is always the combination of one wireless client and one wired client; never two wired or two wireless. The only device on the network setup as a DHCP server is that one 2003 server, the Wireless LAN controller is not setup to give out addresses. Is there a problem with my setup on the LAN controller or DHCP or what could the problem be? Any advice would be greatly appreciated. Thanks

 

[Ravenrx7]

is there a option for passive DHCP on the cisco controller?

Josh McMahon
A+ Certified,CCNA
sold@joshmcmahon.com

 

[bingerthedog]

I didn't see an option for passive DHCP, but there is an option for Internal DHCP Server and I am not using that. I also found if I go to Edit under WLANs there is a DHCP override checkbox where I can specify an IP address for a DHCP server. I checked that box and specified the IP address, but I don't think that is going to do anything since it was finding the DHCP server before.

 

[bingerthedog]

By the way the Wireless Controller is a 2106, I'm not sure if that helps at all.

 

[bingerthedog]

Another thing we noticed is that when you do an ipconfig /all after getting an ip address wirelessly the DHCP server is said to be 1.1.1.1, is this normal for Cisco devices?

 

[joemadera]

Check your DHCP server scope and see which MAC is getting which IP lease.

For example, if both a wireless and a lan machine get 192.168.2.5, quickly check in the dhcp scope and see who's mac is listed.

The gateway that is used to forward these dhcp requests to the server should dictate which range they recieve.

If both are using the same gateway (you will get both using the same range. ) You can also use the Conflict Detection option under the dhcp server Properties | Advanced. Set that for two for awhile and see what happens.