Operation Manual – DHCPH3C S5600 Series Ethernet Switches Chapter 3 DHCP Relay Agent Configuration3-8Note:Currently, the DHCP relay agent handshake function on a S5600 series switch can onlyinteroperate with a Windows 2000 DHCP server.III. Enabling unauthorized DHCP server detectionIf there is an unauthorized DHCP server in the network, when a client applies for an IPaddress, the unauthorized DHCP server may assign an incorrect IP address to theDHCP client.With this feature enabled, upon receiving a DHCP message with the siaddr field (IPaddresses of the servers offering IP addresses to the client) not being 0 from a client,the DHCP relay agent will record the value of the siaddr field and the receiving interface.The administrator can use this information to check out any DHCP unauthorizedservers.Follow these steps to enable unauthorized DHCP server detection:To 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 relay agent will log allDHCP servers, including authorized ones, and each server is recorded only once untilsuch information is removed and is recorded again. The administrator needs to findunauthorized DHCP servers from the system log information.3.2.5 Configuring the DHCP Relay Agent to Support Option 82I. PrerequisitesBefore configuring Option 82 support on a DHCP relay agent, you need to:z Configure network parameters and relay function of the DHCP relay device.z Perform assignment strategy-related configurations, such as network parametersof the DHCP server, address pool, and lease time.z The routes between the DHCP relay agent and the DHCP server are reachable.
