DHCP L2 Relay VLAN Configuration

Use the DHCP L2 Relay VLAN Configuration page to control the DHCP (Dynamic Host Configuration Protocol) Layer 2 relay settings on a particular VLAN. The VLAN is identified by a service VLAN ID (S-VID), which a service provider uses to identify a customer's traffic while traversing the provider network to multiple remote sites. The device uses the VLAN membership of the switch port client (the customer VLAN ID, or C-VID) to perform a lookup on a corresponding S-VID.

To access this page, click Switching > DCHP Snooping > L2 Relay > VLAN Configuration in the navigation menu.

Use the buttons to perform the following tasks:

To enable a VLAN for DHCP Layer 2 relay, click Add and select the VLAN from the available menu.
To update the DHCP Layer 2 relay settings for one or more VLANs, select each entry to update and click Edit. The same settings are applied to all selected VLANs.
To disable one or more VLANs as DHCP Layer 2 relay agents, select the appropriate VLANs and click Remove. You must confirm the action.

DHCP L2 Relay VLAN Configuration Fields

Field	Description
VLAN ID	The VLAN associated with the rest of the data in the row. When configuring the settings for one or more VLANs, this field identifies each VLAN that is being configured.
Circuit ID	The administrative mode of the circuit ID. When enabled, if a client sends a DHCP request to the device and the client is in a VLAN that corresponds to the S-VID, the device adds the client's interface number to the Circuit ID sub-option of Option 82 in the DHCP request packet. This enables the device to reduce the broadcast domain to which the server replies are switched when the broadcast bit is set for DHCP packets. When this bit is set, the server is required to echo Option 82 in replies. Since the circuit-id field contains the client interface number, the Layer 2 relay agent can forward the response to the requesting interface only, rather to all ports in the VLAN).
Remote ID	The DHCP remote identifier string. When a string is entered here, if a client sends a DHCP request to the device and the client is in a VLAN that corresponds to the S-VID, the device adds the string to the Remote-ID sub-option of Option 82 in the DHCP request packet. This sub-option can be used by the server for parameter assignment. The content of this option is vendor-specific.