The Renew/Rebind process will go on till the lease time expires. Spirent TestCenter behavior is behaving in conformance with the RFC 2131, section 4.4.5 Reacquisition and expiration. Client will continue to renew till the T1 timer expiry and rebind till the T2 timer expiry. And If the lease expires before the client receives a DHCPACK, the client moves to INIT state, MUST immediately stop any other network processing and requests network initialization parameters as if the client were uninitialized