Wireless Access

DHCP is disabled, however Aruba controller is giving ip to a client. External DHCP sever is giving the same ip to another client...

Any solutions??

Hi,

Sorry there is a correction..

The Aruba Controller is not giving ip address to the client..

One client is getting ip address from external DHCP server.

However in the Aruba user table there are two clients with the same ip address. 

The external DHCP server user table shows only one.

There is an ip conflict.

No static ip's assigned.

will "enforce dhcp" option help?

Thats right. Here both are using DHCP

But why would two clients get the same IP in same network? One client without the external DHCP server knowing?

Could this be an issue with the DHCP server?

These are two WIRELESS clients with the same IP address? How are two clients getting the same IP address from two different DHCP servers? Knowing what DHCP servers are where, what your helper IP addresses are, and what VLANs and networks they are all in (network drawings help), then you can start to run it down. What I have seen in the past is the domain guys stand up two 'redundant' Windows DHCP servers, but they don't cluster them, and they both either share the same scope, or it overlaps a bit. For every DHCP request, it's a race condition with two offers being made but only one taken. Eventually they will both issue the same IP from their available pool, or one will issue an IP from a pool while the other one has an active lease.

Sounds like there's either a network corssing over, or there are two DHCP servers handing out the same scope.

Hello,

are these windows machines?

do following command on both machines in cmd-promt:

ipconfig /all

There you should see the DHCP servers IP from which the client got an IP address.

An other thing that you should check:

what is the user session timeout on the controller?

what is your lease  time on your DHCP server?

your user session timeout should be < 1/2 of the DHCP lease time.

Because if the session timeout is bigger: your client will idle/sleep and will keep the entry in the user-table (with the IP address), while on the DHCP server the lease time will expire and it will give out the IP Address again to an other client what will cause a conflict.

Kr,

have never seen a controller hand out IP addresses if the DHCP service was disabled. Do you only have one DHCP server for your network? If you have multiple controllers is it disabled on ALL controllers? 

If you log in to the CLI and run 

show ip dhcp stat

show ip dhcp bind

That will tell you if the controller is actually handing out IP addresses.