Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

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Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE 26.1.x

Configure DHCP Option 82 through a VLAN interface

Updated: April 10, 2026

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Outlines procedures for configuring DHCP Option 82 on VLAN interfaces and SVIs using commands such as option-insert, server-ID-override, and subscriber-ID, including steps for VLAN and SVI setup, suboption configuration, IP assignment, UDP relay settings, and disabling MOP features for DHCP relay control.

Configure DHCP Option 82 through option-insert command (CLI)

Enable DHCP Option 82 insertion on a VLAN interface to provide relay agent information in DHCP packets.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Configure a VLAN ID.

Example:

Device(config)# interface vlan vlan-id
3.

Insert relay information in BOOTREQUEST.

Example:

Device(config-if)# ip dhcp relay information option-insert
4.

Configure the IP address for the interface.

Example:

Device(config-if)# ip address ip-address
5.

Configure the destination address for UDP broadcasts.

Example:

Device(config-if)# ip helper-address ip-address
6.

Disable the MOP for an interface.

Example:

Device(config-if)# no mop enabled
7.

Disable the task of sending MOP periodic system ID messages.

Example:

Device(config-apgroup)# no mop sysid

DHCP requests sent from this VLAN interface will contain Option 82 relay information to aid in DHCP server assignment and troubleshooting.

Device# configure terminal
Device(config)# interface vlan 72
Device(config-if)# ip dhcp relay information option-insert
Device(config-if)# ip address 9.3.72.38 255.255.255.0
Device(config-if)# ip helper-address 9.3.72.1
Device(config-if)# no mop enabled
Device(config-apgroup)# no mop sysid

Configure DHCP Option 82 through server-ID-override command (CLI)

Enable DHCP Option 82 with server-ID override to control how DHCP relay information is inserted on a Cisco device.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Configure the server-id override suboption to use an RFC-specific or Cisco-specific value.

Example:

Device(config)# ip dhcp compatibility suboption server-override cisco
3.

Configure the link-selection suboption to use an RFC-specific or Cisco-specific value.

Example:

Device(config)# ip dhcp compatibility suboption link-selection cisco
4.

Configure a VLAN ID.

Example:

Device(config)# interface vlan vlan-id
5.

Insert the server-id override suboption and link-selection suboption.

Example:

Device(config-if)# ip dhcp relay information option server-id-override
6.

Configure the IP address for the interface.

Example:

Device(config-if)# ip address ip-address
7.

Configure the destination address for UDP broadcasts that your interfce will use.

Example:

Device(config-if)# ip helper-address ip-address
8.

Disable MOP for an interface.

Example:

Device(config-if)# no mop enabled
9.

Disable the task of sending MOP periodic system ID messages.

Example:

Device(config-if)# [no] mop sysid

The device uses the specified server-id override and link-selection options in DHCP Option 82 relay messages, which the device forwards through the configured VLAN interface.

Device# configure terminal
Device(config)# ip dhcp compatibility suboption server-override cisco
Device(config)# ip dhcp compatibility suboption link-selection cisco 
Device(config)# interface vlan 72
Device(config-if)# ip dhcp relay information option server-id-override
Device(config-if)# ip address 9.3.72.38 255.255.255.0
Device(config-if)# ip helper-address 9.3.72.1
Device(config-if)# no mop enabled
Device(config-if)# no mop sysid

Configure DHCP Option 82 through a subscriber-ID (CLI)

Configure DHCP Option 82 through a subscriber-ID.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Configure a VLAN ID.

Example:

Device(config)# interface vlan vlan-id
3.

Insert the subscriber identifier suboption to include the subscriber ID in DHCP messages.

Example:

Device(config-if)# ip dhcp relay information option subscriber-id subscriber-id
4.

Configure the IP address for the interface.

Example:

Device(config-if)# ip address ip-address
5.

Configure the destination address for UDP broadcasts.

Example:

Device(config-if)# ip helper-address ip-address
6.

Disable MOP for an interface.

Example:

Device(config-if)# no mop enabled
7.

Disable the task of sending MOP periodic system ID messages.

Example:

Device(config-apgroup)# no mop sysid

The system now inserts the subscriber-ID suboption (DHCP Option 82) into relayed DHCP packets on the specified VLAN interface.

Device# configure terminal
Device(config)# interface vlan 72
Device(config-if)# ip dhcp relay information option subscriber-id test10
Device(config-if)# ip address 9.3.72.38 255.255.255.0
Device(config-if)# ip helper-address 92.0.2.1
Device(config-if)# no mop enabled
Device(config-apgroup)# no mop sysid

Configure DHCP Option 82 through server-ID-override and subscriber-ID commands (CLI)

Enable customized handling of DHCP Option 82 information for relayed DHCP requests by setting server and subscriber ID options.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Configure a VLAN ID.

Example:

Device(config)# interface vlan vlan-id
3.

Insert server ID override and link selection suboptions.

Example:

Device(config-if)# ip dhcp relay information option server-id-override
4.

Insert the subscriber identifier suboption.

Example:

Device(config-if)# ip dhcp relay information option subscriber-id subscriber-id
5.

Configure the IP address for the interface.

Example:

Device(config-if)# ip address ip-address
6.

Configure the destination address for UDP broadcasts.

Example:

Device(config-if)# ip helper-address ip-address
7.

Disable the MOP for an interface.

Example:

Device(config-if)# no mop enabled
8.

Disable the task of sending MOP periodic system ID messages.

Example:

Device(config-apgroup)# no mop sysid

The interface relays DHCP requests with Option 82 data, including server ID override and subscriber ID.

Device# configure terminal
Device(config)# interface vlan 72
Device(config-if)# ip dhcp relay information option server-id-override
Device(config-if)# ip dhcp relay information option subscriber-id test10
Device(config-if)# ip address 9.3.72.38 255.255.255.0
Device(config-if)# ip helper-address 9.3.72.1
Device(config-if)# no mop enabled
Device(config-apgroup)# no mop sysid

Configure DHCP Option 82 through different SVIs (CLI)

Enable DHCP Option 82 using different switch virtual interfaces (SVIs) for relayed requests.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Configure a VLAN ID.

Example:

Device(config)# interface vlan vlan-id
3.

Configure a source interface on the VLAN to relay messages.

Example:

Device(config-if)# ip dhcp relay source-interface vlan vlan-id
4.

Configure the IP address for the interface.

Example:

Device(config-if)# ip address ip-address
5.

Configure the destination address for UDP broadcasts.

Example:

Device(config-if)# ip helper-address ip-address
6.

Disable the Maintenance Operations Protocol (MOP) on the interface.

Example:

Device(config-if)# no mop enabled
7.

Disable periodic system ID message transmission for MOP.

Example:

Device(config-apgroup)# no mop sysid

The device relays DHCP messages with Option 82 through the configured VLAN SVIs.

Device# configure terminal
Device(config)# interface vlan 72
Device(config-if)# ip dhcp relay source-interface vlan 74
Device(config-if)# ip address 9.3.72.38 255.255.255.0
Device(config-if)# ip helper-address 9.3.72.1
Device(config-if)# no mop enabled
Device(config-apgroup)# no mop sysid