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-interface vlan-id —Configure the VLAN interface toobtain IP address through DHCPor BOOTPip address { bootp-alloc |dhcp-alloc }RequiredBy default, no IP address isconfigured for the VLAN interface.z Currently, an S5600 Ethernet switch functioning as the DHCP client can use an IP address for 24days at most. That is, the DHCP client can obtain an address lease for no more than 24 days eventhough the DHCP server offers a longer lease period.z If a switch belongs to an IRF fabric, you need to enable the UDP Helper function on the switchbefore configuring its VLAN interfaces to obtain IP addresses through DHCP.To improve security and avoid malicious attack to the unused SOCKETs, S5600 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.DHCP Client Configuration ExampleNetwork requirementsUsing DHCP, VLAN-interface 1 of Switch B is connected to the LAN to obtain an IP address from theDHCP server.Network diagramSee Figure 2-1.Configuration procedureThe following describes only the configuration on Switch B serving as a DHCP client.# Configure VLAN-interface 1 to dynamically obtain an IP address by using DHCP. system-view[SwitchB] interface Vlan-interface 1
