Operation Manual – DHCPH3C S7500E Series Ethernet Switches Chapter 2 DHCP Server Configuration2-15To do… Use the command… RemarksEnter system view system-view —Enable unauthorizedDHCP server detection dhcp server detect RequiredDisabled by default.Note:With the unauthorized DHCP server detection enabled, the device puts a record oncefor each DHCP server. The administrator needs to find unauthorized DHCP serversfrom the log information.2.6.3 Configuring IP Address Conflict DetectionTo avoid IP address conflicts, the DHCP server checks whether the address to beassigned is in use via sending ping packets.The DHCP server pings the IP address to be assigned using ICMP. If the server gets aresponse within the specified period, the server will ping another IP address; otherwise,the server will ping the IP addresses once again until the specified number of pingpackets are sent. If still no response, the server will assign the IP address to therequesting client (The DHCP client probes the IP address by sending gratuitous ARPpackets).Follow these steps to configure IP address conflict detection:To do… Use the command… RemarksEnter system view system-view —Specify the number ofping packetsdhcp server pingpackets numberOptionalOne ping packet by default.The value 0 indicates that noping operation is performed.Configure a timeoutwaiting for pingresponsesdhcp server pingtimeout millisecondsOptional500 ms by default.The value 0 indicates that noping operation is performed.2.7 Configuring the Handling Mode for Option 82When the DHCP server receives a message with Option 82, if the server is configuredto handle Option 82, it will return a response message carrying Option 82 to assign anIP address to the requesting client.
