2-23To do… Use the command… RemarksEnable the unauthorized DHCP serverdetecting function dhcp server detect RequiredDisabled by default.With the unauthorized DHCP server detection enabled, the relay agent will log all DHCP servers,including authorized ones, and each server is recorded only once. The administrator needs to findunauthorized DHCP servers from the system log information.Configuring IP Address DetectingTo avoid IP address conflicts caused by assigning the same IP address to multiple DHCP clientssimultaneously, you can configure a DHCP server to detect an IP address before it assigns the addressto a DHCP client.The DHCP server pings the IP address to be assigned using ICMP. If the server gets a response withinthe specified period, the server will ping another IP address; otherwise, the server will ping the IPaddresses once again until the specified number of ping packets are sent. If still no response, the serverwill assign the IP address to the requesting client (The DHCP client probes the IP address by sendinggratuitous ARP packets).Follow these steps to configure IP address detecting:To do… Use the command… RemarksEnter system view system-view —Specify the number of pingpacketsdhcp server ping packetsnumberOptionalTwo ping packets by default.Configure a timeout waiting forping responsesdhcp server ping timeoutmillisecondsOptional500 ms by default.Configuring DHCP Accounting FunctionsIntroduction to DHCP AccountingDHCP accounting allows a DHCP server to notify the RADIUS server of the start/end of accountingwhen it assigns/releases a lease. The cooperation of DHCP server and RADIUS server implements thenetwork accounting function and ensures network security at the same time.DHCP Accounting FundamentalsAfter you complete AAA and RADIUS configuration on a switch with the DHCP server function enabled,the DHCP server acts as a RADIUS client. For the authentication process of the DHCP server acting asa RADIUS client, refer to AAA Operation in this manual. The following describes only the accountinginteraction between DHCP server and RADIUS server.
