Resolution
T1 Timer(Renewal) After a certain portion of the lease time has expired, you attempt to contact the server that initially granted the lease in order to renew the lease so its IP address can still be used.
T2 Timer(Rebinding) If renewal with the original leasing server fails, because, for example, the server was taken offline, then you ideally try to rebind to any active DHCP server and try to extend its current lease with any server that allows it to do so.
These T1 and T2 timers can be any values, but must be less than the IP address lease duration. T1 Timer must be less than T2. Generally T1 is set to 50 percent of the lease duration and T2 is set to 87.5 percent of the lease duration. Use this rule to set T1 and T2 timers.
Refer to these documents for more information:
