3Com WX3000 operation manual Configuring the Dhcp Relay Agent to Support Option, Prerequisites

To do…	Use the command…	Remarks
Set the interval at which the		Optional
DHCP relay agent dynamically	dhcp-security tracker	By default, auto is adopted, that
updates the client address	{ interval auto }	is, the interval is automatically
entries		calculated.

Enabling unauthorized DHCP server detection

If there is an unauthorized DHCP server in the network, when a client applies for an IP address, the unauthorized DHCP server may assign an incorrect IP address to the DHCP client.

With this feature enabled, upon receiving a DHCP message with the siaddr field (IP addresses of the servers offering IP addresses to the client) not being 0 from a client, the DHCP relay agent will record the value of the siaddr field and the receiving interface. The administrator can use this information to check out any DHCP unauthorized servers.

Follow these steps to enable unauthorized DHCP server detection:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Enable unauthorized DHCP server	dhcp-server detect	Required
detection		Disabled by default.

With the unauthorized DHCP server detection enabled, the relay agent will log all DHCP servers, including authorized ones, and each server is recorded only once until such information is removed and is recorded again. The administrator needs to find unauthorized DHCP servers from the system log information.

Configuring the DHCP Relay Agent to Support Option 82

Prerequisites

Before configuring Option 82 support on a DHCP relay agent, you need to:

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Configure network parameters and relay function of the DHCP relay device.

Perform assignment strategy-related configurations, such as network parameters of the DHCP server, address pool, and lease time.

The routes between the DHCP relay agent and the DHCP server are reachable.

Configuring the DHCP relay agent to support Option 82

Follow these steps to configure the DHCP relay agent to support Option 82:

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