dhcp option82 rebuild enable (interface view)

Function

The dhcp option82 rebuild enable command enables a device to forcibly insert Option 82 into DHCP packets.

The undo dhcp option82 rebuild enable command disables a device from forcibly inserting Option 82 into DHCP packets.

By default, a device is disabled from forcibly inserting Option 82 into DHCP packets.

Format

dhcp option82 rebuild enable

undo dhcp option82 rebuild enable

Parameters

None

Views

100GE interface view, 10GE interface view, 25GE interface view, 400GE Layer 2 sub-interface view, 400GE interface view, 40GE interface view, 50GE Layer 2 sub-interface view, 50GE interface view, Eth-Trunk Layer 2 sub-interface view, Eth-Trunk interface view, FlexE sub-interface view, FlexE interface view, GE Layer 2 sub-interface view, GE optical interface view, GE interface view, GE electrical interface view, Global VE sub-interface view, VE sub-interface view, VLANIF interface view, Layer 2 sub-interface view, Sub-interface view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
dhcp	write

Usage Guidelines

Usage Scenario

The option fields in a DHCP packet store some control information and parameters that are not defined in common protocols. An option field consists of the Code, Length, and Value. The option 82 field refers to the option field in which the value of Code is 82.

The option 82 field contains the location information of DHCP hosts, such as information about login interface, VLAN, and address. The option 82 field helps create DHCP snooping binding entries with accurate interface information. DHCP relays specify clients and policies for IP address assignment based on the option 82 field. For example, the DHCP server assigns IP addresses in a network segment for the clients that logs in from Ethernet 0/1/1. The DHCP server assigns IP addresses in another network segment for the clients that logs in from Ethernet 0/1/2.

Configuration Impact

After the dhcp option82 rebuild enable command is run, the device inserts the Option 82 field into a DHCP packet if no Option 82 field exists in the packet. If the Option 82 field exists in a DHCP packet, the device deletes the Option 82 field and inserts a new Option 82 field into the packet.

If the dhcp option82 rebuild enable command and the dhcp option82 insert enable (interface view) command are run in the BD view, the later configuration takes effect.

After the dhcp option82 rebuild enable command is run, the device inserts the Option 82 field into a DHCP packet if no Option 82 field exists in the packet. If the Option 82 field exists in a DHCP packet, the device deletes the Option 82 field and inserts a new Option 82 field into the packet.
If the dhcp option82 rebuild enable command and the dhcp option82 insert enable (BD view) command are run in the BD view, the later configuration takes effect.

Example

# Enable forcible Option 82 insertion on GE 0/1/0.

<HUAWEI> system-view
[~HUAWEI] dhcp enable
[~HUAWEI] interface GigabitEthernet 0/1/0
[*HUAWEI-GigabitEthernet0/1/0] dhcp option82 rebuild enable