Configuring The Dhcp Relay Agent To Support Option 82 - 3Com 4200G 12-Port Configuration Manual

The address-check enable command is independent of other commands of the DHCP relay
agent. That is, the invalid address check takes effect when this command is executed, regardless
of whether other commands (such as the command to enable DHCP) are used.
Before executing the address-check enable command on the interface connected to the DHCP
server, you need to configure the static binding of the IP address to the MAC address of the DHCP
server. Otherwise, the DHCP client will fail to obtain an IP address.
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...
Enter system view
Enable unauthorized DHCP
server detection
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:
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.
Enabling Option 82 support on a DHCP relay agent
Follow these steps to enable Option 82 support on a DHCP relay agent:
Use the command...
system-view
dhcp-server detect
2-6
Remarks
—
Required
Disabled by default.