Possible causes include:
1. Mechanism difference
2. DHCP server fault
3. Client fault
The problem in this case was caused due to mechanism difference.
1. According to the related RFC description, a DHCP client that has obtained an IP address preferred to use the previously obtained address after being reset, and initiates a procedure to apply for extension of the IP address lease. If the application is approved, the lease extends. Otherwise, the client starts a new DHCP procedure to apply for an IP address. This means, within the lease, the client should be allocated the previously obtained address preferably as long as the address is not allocated to another client
2. Got information of packets to analyze the problem.
After being reset, the client sent two discovery packets. Upon receiving the first packet, the ME60 released the client and sent a release message to the DCHP server to instruct it to release the address that had been allocated to the client. The ME60 transparently transmitted the second discovery packet to the DHCP server. Therefore, the DHCP server allocated a new IP address to the client.
3. Checked for difference in processing DHCP packets on the ME60 and MA5200G.On MA5200G, dhcp through-packet was enabled, whereas on ME60 V600R002C02SPC700, the function was disabled by default, which caused the problem.