3Com Router 3000 Ethernet FamilyConfiguration Guide Chapter 9 DHCP Configuration3Com Corporation9-38Table 9-40 Set multiple interfaces to operate in DHCP relay modeOperation CommandRelay DHCP packets to an externalDHCP server for address allocationdhcp select relay { interfaceinterface-type interface-number [ tointerface-type interface-number ] | all }Resets the defaultundo dhcp select { interfaceinterface-type interface-number [ tointerface-type interface-number ] | all }By default, dhcp select global applies.Currently DHCP relay is available on following interfaces:z Ethernet interface (subinterface)z Virtual Ethernet interfacez Synchronous/asynchronous serial interface encapsulated with PPP, HDLC, orframe relayz E1 interfaceNote:When a PC wants to obtain an IP address through the DHCP relay on an Ethernetsubinterface on the router, the PC needs to connect to the router through a switch. Inthis case, you need to make proper link configuration on the switch beforehand.9.6.2 Specifying External DHCP ServersWhen receiving a DHCP broadcast, the interface with DHCP relay enabled relays theDHCP broadcast to the specified external DHCP server.Perform the following configuration in interface view to specify an external DHCPserver address to which the received DHCP broadcasts are to be forwarded.Table 9-41 Specify an external DHCP server address on the current interfaceOperation CommandSpecify an external DHCP serveraddress on the current interface ip relay address ip-addressDelete one or all external DHCP serveraddresses on the current interfaceundo ip relay address { ip-address |all }
