(Realize the centralized management and automatic address allocation of IP addresses. Only authorized users in the company's network can connect to the intranet, enhance the security of the intranet, accurately grasp the network resources of IP addresses that can be used in the intranet, provide a favorable basis for the purchase of new network equipment and the reporting of waste equipment, and save budget costs. Link the dhcpssnooping+dai function of the switch to solve IP conflicts, MAC address deception and other phenomena)