Operation Manual – DHCPH3C S5500-EI Series Ethernet Switches Chapter 3 DHCP Relay Agent Configuration3-8III. Enabling unauthorized DHCP servers detectionThere are unauthorized DHCP servers on networks, which reply DHCP clients withwrong IP addresses.With this feature enabled, upon receiving a DHCP request, the DHCP relay agent willrecord the IP address of the DHCP server which assigned an IP address to the DHCPclient and the receiving interface. The administrator can use this information to checkout any DHCP unauthorized servers.Follow these steps to enable unauthorized DHCP server detection:To do… Use the command… RemarksEnter system view system-view —Enable unauthorizedDHCP server detection dhcp relay 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. After the recorded information of a DHCP server is cleared, anew record will be put for the DHCP server.3.3.6 Configuring the DHCP Relay Agent to Support Option 82I. PrerequisitesYou need to complete the following tasks before configuring the DHCP relay agent tosupport Option 82.z Enabling DHCPz Enabling the DHCP relay agent on the specified interfacez Correlating a DHCP server group with relay agent interfacesII. Configuring the DHCP relay agent to support Option 82Follow these steps to configure the DHCP relay agent to support Option 82:To do… Use the command… RemarksEnter system view system-view —Enter interface view interface interface-typeinterface-number —Enable the relay agent tosupport Option 82dhcp relay informationenableRequiredDisabled by default.
