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DHCP lease renewal on T21p - Printable Version

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DHCP lease renewal on T21p - Guido - 10-23-2015 05:10 PM


we have a mix of T21P phones and T42G phones. On the DHCP server (windows 2003 server) we keep getting the status "This address is already in use" on several leases. When we browse to the IP adres it is always a T21P. Never a T42G.
The lease duration on the DHCP scope is 8 days.
We have firmware version on the T21P

I think the T21P is not doing a lease renewal and keeps using the IP adress. Resulting in a conflict when there is a dhcp request on the server.

Please help

RE: DHCP lease renewal on T21p - Yealink_Michael - 10-24-2015 04:21 AM

hi Guido

thanks for your information

for this issue, please do the steps below :

1. Clear the cache of the DHCP server
2. reset the T21P to factory and test again



RE: DHCP lease renewal on T21p - Guido - 11-10-2015 09:07 PM

After factory reset same problem.
We have about 40 T21p's and 60 T42G's. Only the T21P's have this problem.
I've put reservations for the T21p's on the dhcp server as a workaround.

RE: DHCP lease renewal on T21p - tsukraw - 11-11-2015 01:48 PM

I know this is not a "Solution" to the issue. But could be a temp fix.
In your DHCP, right click the server, go to Advanced, and set Conflict Detection to 1.

Here is a video if your not sure and want to see how.

What this will do is when a DHCP request comes in, DHCP thinks it has a open IP, DHCP will try to communicate with that IP, as long as there is no response it will give out a lease.
If something communicates back on the IP, DHCP will mark it as in use and go to the next available IP. (This will add no more then a second or two to the DHCP leasing process, nothing a user will notice)

Learned this trick back from the 3CX NBX Phone system days where there phones would not renew DHCP leases after X number of days... Like what you are discribing.

Like i said not a "Fix" but will get you through a bit of the pain.