6-2Configuring a DHCP/BOOTP ClientFollow these steps to configure a DHCP/BOOTP client:To do… Use the command… RemarksEnter system view system-view —Enter VLAN interface view interface vlan-interfacevlan-id —Configure the VLAN interfaceto obtain IP address throughDHCP or BOOTPip address { bootp-alloc |dhcp-alloc }RequiredBy default, no IP address isconfigured for the VLANinterface.z Currently, an S5500-EI Ethernet switch functioning as the DHCP client can use an IP address for24 days at most. That is, the DHCP client can obtain an address lease for no more than 24 dayseven though the DHCP server offers a longer lease period.z An S5500-EI Ethernet switch functioning as a DHCP client supports default route creation. That is,the DHCP client creates a default route with the next hop being the gateway assigned by the DHCPserver. To view detailed information about the default route, run the display ip routing-tablecommand on the switch.z If a switch belongs to an XRN fabric, you need to enable the UDP Helper function on the switchbefore configuring its VLAN interfaces to obtain IP addresses through DHCP.z An S5500-EI Ethernet switch functioning as a DHCP client supports default route creation. That is,the DHCP client creates a default route with the next hop being the gateway assigned by the DHCPserver. To view detailed information about the default route, run the display ip routing-tablecommand on the switch.To improve security and avoid malicious attack to the unused SOCKETs, S5500-EI Ethernet switchesprovide the following functions:z UDP 67 and UDP 68 ports used by DHCP are enabled only when DHCP is enabled.z UDP 67 and UDP 68 ports are disabled when DHCP is disabled.The specific implementation is:z Using the ip address dhcp-alloc command enables the DHCP client, and UDP port 68.z Using the undo ip address dhcp-alloc command disables the DHCP client, and UDP port 68.
