Wireless Access

Contributor II

Migration to external DHCP server

We are looking at migrating from internal DHCP server on controller to external Windows DHCP server for our VLAN 200.

We have 4 controllers and are testing on one (C4) to start with.

VLAN 200 exists on all controllers - but each controller is trunning it's own DHCP for it's own 192.168.X.X range.


C4 - had a DHCP scope of


So we set this up on the external DHCP server and set up the fowarder IP to point to External DHCP server and disabled the DHCP server through GUI on C4 controller.


Problem we see is that when I connect an ipad to Virtual AP on Controller 4 set to VLAN 200 - we see the following in the DHCP logs:


Aug 14 15:45:03 :202536:  <DBUG> |dhcpdwrap| |dhcp| Datapath vlan200: REQUEST 34:51:c9:df:XX:XX reqIP=


It seems the IPAD with MAC address shown is requesting an IP from a DHCP range that is not present on this controller (202-211 - not 212-215)


Is this because it was preivously connected to a controller and it is trying to preserve the IP due to mobility settings?


What happens is it basically times out and the ipad gets a 169.X.X.X address.


The Actual 192.168.208.X - 192.168.211.X scope is also configured on the Windows DHCP server - but obvioulsy the DHCP server is seeing the request coming from a address and hence would logically try and assign from that scop - not the 208-211 scope.


But the ipad seems to be trying to request it's old address?


What am I missing here? Is this failing by design?




Trusted Contributor I

Re: Migration to external DHCP server

odd, devices can request an IP in their DHCP request, but a DHCP server can just give another one and they should accept that. can you see if the DHCP replies with anything?


have you tried cleaning any wireless / network settings from the tablet?

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