3-4To do… Use the command… RemarksEnable the DHCP relay agenton the current interface dhcp select relayRequiredWith DHCP enabled, interfaceswork in the DHCP server mode.If the DHCP client obtains an IP address via the DHCP relay agent, the address pool of the subnet towhich the IP address of the DHCP relay agent belongs must be configured on the DHCP server.Otherwise, the DHCP client cannot obtain a correct IP address.Correlating a DHCP Server Group with a Relay Agent InterfaceTo improve reliability, you can specify several DHCP servers as a group on the DHCP relay agent andcorrelate a relay agent interface with the server group. When the interface receives requestingmessages from clients, the relay agent will forward them to all the DHCP servers of the group.Follow these steps to correlate a DHCP server group with a relay agent interface:To do… Use the command… RemarksEnter system view system-view —Create a DHCP server groupand add a server into the groupdhcp relay server-group group-idip ip-addressRequiredNot created by default.Enter interface view interface interface-typeinterface-number —Correlate the DHCP servergroup with the current interface dhcp relay server-select group-idRequiredBy default, no interface iscorrelated with any DHCPserver group.z You can specify up to twenty DHCP server groups on the relay agent and up to eight DHCP serveraddresses for each DHCP server group.z The IP addresses of DHCP servers and those of relay agent’s interfaces cannot be on the samesubnet. Otherwise, the client cannot obtain an IP address.z A DHCP server group can correlate with one or multiple DHCP relay agent interfaces, while a relayagent interface can only correlate with one DHCP server group. Using the dhcp relayserver-select command repeatedly overwrites the previous configuration. However, if thespecified DHCP server group does not exist, the interface still uses the previous correlation.z The group-id argument in the dhcp relay server-select command is configure by using the dhcprelay server-group command.
