Enabling the DHCP Client Function

Context

Before a device can function as a DHCP client, you must enable the DHCP client function.

After an interface is enabled with the DHCP client function, the interface can obtain network parameters including the IP address from the DHCP server. If the allocated IP address and IP addresses of other interfaces are on the same network segment, the interface does not use this IP address and does not re-apply for an IP address. To allow the interface to re-apply for an IP address, run the shutdown and then the undo shutdown commands on the interface. Alternatively, run the undo ip address dhcp-alloc and then the ip address dhcp-alloc command on the interface.

Procedure

Enter the system view.
```
system-view
```
Enter the interface view or sub-interface view.
```
interface interface-type interface-number [.subinterface-number ]
```
Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731S-H, S5731-S, S5731S-S, S6720-HI, S5732-H, S6730-H, S6730S-H, S6730-S, S6730S-S, S6720-EI, and S6720S-EI support sub-interfaces.
(Optional) On an Ethernet interface, run undo portswitch
The interface is switched to Layer 3 mode.

By default, an Ethernet interface works in Layer 2 mode.

Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support switching between Layer 2 and Layer 3 modes.
Enable the DHCP client function.
```
ip address dhcp-alloc
```
By default, the DHCP client function is disabled on an interface.