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DES-3010F/DES-3010FL/DES-3010G/DES-3016/DES-3018/DES-3026 Fast Ethernet Switch Manual

DHCP Relay Agent

Information Option 82

State

DHCP Relay Agent

Information Option 82

Check

DHCP Relay Agent

Information Option 82

Policy

Enabled – When option 61 is enabled, if the packets do not have option 61 then the relay servers cannot be determined based on option 61. If the relay servers are determined based on option 61 then the IPIF configured servers will be ignored.

Disabled – If the relay server is not determined then the IPIF configured servers will be used to determine the relay servers.

This field can be toggled between Enabled and Disabled using the pull-down menu. It is used to enable or disable the DHCP Agent Information Option 82 on the Switch. The default is Disabled.

Enabled – When this field is toggled to Enabled the relay agent will insert and remove DHCP relay information (option 82 field) in messages between DHCP servers and clients. When the relay agent receives the DHCP request, it adds the option 82 information, and the IP address of the relay agent (if the relay agent is configured), to the packet. Once the option 82 information has been added to the packet it is sent on to the DHCP server. When the DHCP server receives the packet, if the server is capable of option 82, it can implement policies like restricting the number of IP addresses that can be assigned to a single remote ID or circuit ID. Then the DHCP server echoes the option 82 field in the DHCP reply. The DHCP server unicasts the reply to the back to the relay agent if the request was relayed to the server by the relay agent. The switch verifies that it originally inserted the option 82 data. Finally, the relay agent removes the option 82 field and forwards the packet to the switch port that connects to the DHCP client that sent the DHCP request.

Disabled - If the field is toggled to Disabled the relay agent will not insert and remove DHCP relay information (option 82 field) in messages between DHCP servers and clients, and the check and policy settings will have no effect.

This field can be toggled between Enabled and Disabled using the pull-down menu. It is used to enable or disable the Switches ability to check the validity of the packet’s option 82 field.

Enabled – When the field is toggled to Enable, the relay agent will check the validity of the packet’s option 82 field. If the switch receives a packet that contains the option-82 field from a DHCP client, the switch drops the packet because it is invalid. In packets received from DHCP servers, the relay agent will drop invalid messages.

Disabled - When the field is toggled to Disabled, the relay agent will not check the validity of the packet’s option 82 field.

This field can be toggled between Replace, Drop, and Keep by using the pull-down menu. It is used to set the Switches policy for handling packets when the DHCP Agent Information Option 82 Check is set to Disabled. The default is Replace.

Replace - The option 82 field will be replaced if the option 82 field already exists in the packet received from the DHCP client.

Drop - The packet will be dropped if the option 82 field already exists in the packet received from the DHCP client.

Keep -The option 82 field will be retained if the option 82 field already exists in the packet received from the DHCP client.

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NOTE: If the Switch receives a packet that contains the option-82 field from a DHCP client and the information-checking feature is enabled, the switch drops the packet because it is invalid. However, in some instances, you might configure a client with the option-82 field. In this situation, you should disable the information-check feature so that the switch does not remove the option-82 field from the packet. You can configure the action that the switch takes when it receives a packet with existing option-82 information by configuring the DHCP Agent Information Option 82 Policy.

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