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 global interface

Updated: April 10, 2026

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Outlines global DHCP Option 82 configuration using server override settings and different SVIs, including relay agent information setup, link selection suboption enablement, and use of specified source interfaces for DHCP message relaying.

Configure DHCP Option 82 globally through server override (CLI)

Set up DHCP Option 82 settings to override relay agent information in DHCP packets at the server.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Insert the global server override and link selection suboptions.

Example:

Device(config)# ip dhcp-relay information option server-override

The system processes DHCP Option 82 information globally based on server settings.

Device# configure terminal
Device(config)# ip dhcp-relay information option server-override

Configure DHCP Option 82 through server override (CLI)

To enable precise DHCP Option 82 behavior, configure the server override and link-selection suboptions.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Set the server override suboption to either an RFC-specific value or a proprietary value.

Example:

Device(config)# ip dhcp compatibility suboption server-override [cisco | standard]
3.

Set the link selection suboption to either an RFC-specific value or a proprietary value.

Example:

Device(config)# ip dhcp compatibility suboption link-selection [cisco | standard]

DHCP Option 82 operates according to the configured settings.

Device# configure terminal
Device(config)# ip dhcp compatibility suboption server-override cisco
Device(config)# ip dhcp compatibility suboption link-selection cisco

Configure DHCP Option 82 globally through different SVIs (GUI)

Enable DHCP Option 82 to insert relay information for clients across selected SVIs.

Procedure

1.

Choose Configuration > VLAN.
2.

Select a VLAN from the drop-down list.

The Edit SVI window appears.
3.

Click the Advanced tab.
4.

Select an option from the IPv4 Inbound ACL drop-down list.
5.

Select an option from the IPv4 Outbound ACL drop-down list.
6.

Select an option from the IPv6 Inbound ACL drop-down list.
7.

Select an option from the IPv6 Outbound ACL drop-down list.
8.

Enter an IP address in the IPv4 Helper Address field.
9.

Set the status to Enabled if you want to enable the Relay Information Option setting.
10.

Enter the Subscriber ID.
11.

Set the status to Enabled if you want to enable the Server ID Override setting.
12.

Set the status to Enabled if you want to enable the Option Insert setting.
13.

Select an option from the Source-Interface Vlan drop-down list.
14.

Click Update & Apply to Device.

DHCP Option 82 is enabled for the selected SVIs. This allows relay agent information to be included in DHCP requests.

Configure DHCP Option 82 globally through different SVIs (CLI)

Enable DHCP Option 82 globally so that DHCP relayed messages include option 82 information through the specified SVIs.

Procedure

1.

Enter global configuration mode.

Example:

Device# configure terminal
2.

Set global source interface for relayed messages.

Example:

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

The device globally applies DHCP relay with Option 82 information using the specified SVI interface. 

Device# configure terminal
Device(config)# ip dhcp-relay source-interface vlan 72