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New Member

Trouble with DHCP

Hi Friends,


I am facing an issue with DHCP.


I have configured dhcp on my distribution switch.(4507), for Access Points.

I have configured the interface as below;

interface fa5/35

  description to AP

  switchport mode trunk

  switchport trunk native vlan 777

                 no shutdown


 Now my switch is leasing ip address to the APs, but it is continuously renewing the IP addresses every 20 to 30 seconds.

 I checked the interfaces, they are stable.


My DHCP configuration is as below;

Ip dhcp pool AP_MGMT



 option 43 ip


Please advice.



Hall of Fame Super Silver

It is a new request from the

Is it a new request from the AP that is causing the frequent renew of the lease?





New Member

  I suppose that the AP is



I suppose that the AP is sending a new request. Coz, I have three dhcp pools there and none of them is having this problem.


And the interfaces where APs are connected are also consistent.

I din't get a chance for debug. Once I get it, I will update you.


Thank you for the reply.

New Member

  Sorry for the late update.



Sorry for the late update.


The controller was not reachable from the AP's IP address. Had to change the Firewall rule to get it work.

Hall of Fame Super Silver

Thanks for posting back to

Thanks for posting back to the forum to tell us that you have resolved the problem and that it required a change in the firewall rules to get it to work.





New Member

Most likely has nothing to do

Most likely has nothing to do with the problem but why do you use VLAN tagging (trunk mode) on a port to an AP. Seems even stranger when seeing that you provide a native VLAN thus indicating that the device on that port is not able to understand the tagged packets.

I would suggest to change the config of the port to:

description AP

switchport mode access

switchport access vlan 777

New Member

 I am sorry that I din't


I am sorry that I din't mention I am using flexconnect mode.


The APs are in my branch offices.