(Optional) Configuring Option 82 Field Insertion

After Option 82 field insertion is enabled on a device, the device can record the location information of the DHCP client or create binding entries with accurate interface information based on the Option 82 information.

Context

The Option 82 field contains the location information of Dynamic Host Configuration Protocol (DHCP) hosts, such as information about the login interface, virtual local area network (VLAN), and address. After DHCP snooping is configured, the device can create binding entries with accurate interface information based on the Option 82 field. In addition, the DHCP server that supports the Option 82 field can allocate different IP policies to different clients based on the Option 82 information. This provides more flexible address allocation modes.

Procedure

Configure Option 82 field insertion in the VLAN view.
1. Run system-view
  The system view is displayed.
2. Run vlan vlan-id
  The VLAN view is displayed.
3. Run dhcp option82 insert enable [ interface interface-type interface-number ] or dhcp option82 rebuild enable [ interface interface-type interface-number ]
  
  Option 82 field insertion is enabled.
  - After the dhcp option82 insert enable command is run: If no Option 82 field exists in a received DHCP packet, the device inserts the Option 82 field into the packet; if the Option 82 field exists in a received DHCP packet, the device checks whether the Option 82 field contains sub-options. If the Option 82 field contains sub-options, the device does not change the sub-options. If the Option 82 field does not contain sub-options and the sub-option format is configured, the device inserts sub-options into the Option 82 field.
  - After the dhcp option82 rebuild enable command is run: If no Option 82 field exists in a received DHCP packet, the device inserts the Option 82 field into 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.
4. Run quit
  
  Return to the system view.
5. (Optional) Run dhcp option82 inner-vlan insert enable
  
  Option 82 information is encapsulated into the inner and outer VLAN IDs of a double-tagged user packet.
  
  When users go online from a Layer 2 interface or a VLANIF interface and device interworking and upgrade exist, run the dhcp option82 inner-vlan insert enable command to prevent user online failures caused by inconsistency between Option 82 information in the inner and outer VLAN IDs of a double-tagged user packet.
6. Run commit
  The configuration is committed.
Configure Option 82 field insertion in the BD view.
1. Run system-view
  The system view is displayed.
2. Run bridge-domain bd-id
  The BD view is displayed.
3. Run dhcp option82 insert enable
  
  Option 82 field insertion is enabled.
  - After the dhcp option82 insert enable command is run: If no Option 82 field exists in a received DHCP packet, the device inserts the Option 82 field into the packet; if the Option 82 field exists in a received DHCP packet, the device checks whether the Option 82 field contains sub-options. If the Option 82 field contains sub-options, the device does not change the sub-options. If the Option 82 field does not contain sub-options and the sub-option format is configured, the device inserts sub-options into the Option 82 field.
  - After the dhcp option82 rebuild enable command is run: If no Option 82 field exists in a received DHCP packet, the device inserts the Option 82 field into 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.
4. Run commit
  The configuration is committed.
Configure Option 82 field insertion on an interface.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface view is displayed.
3. Run dhcp option82 insert enable or dhcp option82 rebuild enable
  
  Option 82 field insertion is enabled.
  - After the dhcp option82 insert enable command is run: If no Option 82 field exists in a received DHCP packet, the device inserts the Option 82 field into the packet; if the Option 82 field exists in a received DHCP packet, the device checks whether the Option 82 field contains sub-options. If the Option 82 field contains sub-options, the device does not change the sub-options. If the Option 82 field does not contain sub-options and the sub-option format is configured, the device inserts sub-options into the Option 82 field.
  - After the dhcp option82 rebuild enable command is run: If no Option 82 field exists in a received DHCP packet, the device inserts the Option 82 field into 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.
4. (Optional) Run dhcp option82 link-selection insert enable
  The function of inserting sub-option 5 into Option 82 is enabled.
5. (Optional) Run dhcp option82 link-selection subnet-ip-address
  An IP address corresponding to sub-option 5 in Option 82 is configured.
6. (Optional) Run dhcp option82 vendor-specific insert enable
  The device is enabled to insert Option 82's sub-option 9 into a DHCP packet.
7. (Optional) Run dhcp option82 vendor-specific format
  A format is configured for Option 82's sub-option 9 carried in a DHCP packet.
8. Run quit
  
  Return to the system view.
9. (Optional) Run dhcp option82 inner-vlan insert enable
  
  Option 82 information is encapsulated into the inner and outer VLAN IDs of a double-tagged user packet.
  
  When users go online from a Layer 2 interface or a VLANIF interface and device interworking and upgrade exist, run the dhcp option82 inner-vlan insert enable command to prevent user online failures caused by inconsistency between Option 82 information in the inner and outer VLAN IDs of a double-tagged user packet.
10. Run commit
  The configuration is committed.

Follow-up Procedure

After Option 82 field insertion is enabled, you can configure the format of the Option 82 field as required.

Configure the format of the Option 82 field in the VLAN view.
1. Run system-view
  The system view is displayed.
2. Run vlan vlan-id
  The VLAN view is displayed.
3. Run dhcp option82 format { user-defined text | type1 | type2 | self-define self-define | cn-telecom | cn-telecom-inherit } interface interface-type interface-number
  
  The format of the Option 82 field is configured for the VLAN.
4. Run commit
  The configuration is committed.
Configure the format of the Option 82 field on an interface.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface view is displayed.
3. Run dhcp option82 format { self-define extendtext | type1 | type2 | cn-telecom | cn-telecom-inherit } or dhcp option82 { circuit-id | remote-id } format self-define extendtext or dhcp option82 [ circuit-id | remote-id ] format user-defined text
  
  The format of the Option 82 field is configured.
4. Run commit
  The configuration is committed.