3Com 4210G Series, Configuration Manual, Page: 252 / 1133

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Follow these steps to enable unauthorized DHCP server detection:
To do… Use the command… Remarks
Enter system view
system-view
—
Enable unauthorized DHCP
server detection
dhcp relay server-detect
Required
Disabled by default.
With the unauthorized DHCP server detection enabled, the device puts a record once for each DHCP
server. The administrator needs to find unauthorized DHCP servers from the log information. After the
information of recorded DHCP servers is cleared, the relay agent will re-record server information
following this mechanism.
Configuring the DHCP Relay Agent to Send a DHCP-Release Request
This task allows you to release a client’s IP address manually on the DHCP relay agent. After you
configure this task, the DHCP relay agent actively sends a DHCP-RELEASE request that contains the
client’s IP address to be released. Upon receiving the DHCP-RELEASE request, the DHCP server
then releases the IP address for the client; meanwhile, the client’s IP-to-MAC binding entry is removed
from the DHCP relay agent.
Follow these steps to configure the DHCP relay agent in system view to send a DHCP-RELEASE
request:
To do… Use the command… Remarks
Enter system view
system-view
—
Configure the DHCP relay
agent to send a
DHCP-RELEASE request
dhcp relay release ip client-ip
Required
Configuring the DHCP Relay Agent to Support Option 82
Prerequisites
You need to complete the following tasks before configuring the DHCP relay agent to support Option
82.
z
Enabling DHCP
z
Enabling the DHCP relay agent on the specified interface
z
Correlating a DHCP server group with relay agent interfaces