3Com Switch 7750 Configuration Guide

Configuring DHCP Relay Agent 619
This configuration will take effect only after the address checking function of the
DHCP relay agent on the VLAN interface is enabled.
Configuring whether to allow freely-connected clients to pass DHCP
security check
A freely-connected client refers to the client whose IP address and MAC address
are not in the DHCP security table. When the freely-connected client is not
allowed to pass DHCP security check, you cannot access the network on this client
even if the freely-connected client has a valid IP address.
This configuration will take effect only after the address checking function of the
DHCP relay agent on the VLAN interface is enabled.
Configuring Option 82
Support
Prerequisites
Before configuring option 82 supporting on a DHCP relay agent, you need to:
■ Configure network parameters and relay function of the DHCP relay agent.
■ 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 supporting on a DHCP relay agent
The following operations need to be performed on a DHCP relay agent-enabled
network device.
n
To enable option 82, you need to perform the corresponding configuration on the
DHCP server and the DHCP relay agent.
Table 492 Configure whether to allow freely-connected clients to pass DHCP security
check
Operation Command Description
Enter system view system-view -
Enter VLAN interface view interface interface-type
interface-number
-
Forbid freely-connected
clients to pass DHCP security
check
address-check no-matched
enable
Optional
Freely-connected clients are
not allowed to pass DHCP
security check
Table 493 Enable option 82 supporting on a DHCP relay agent
Operation Command Description
Enter system view system-view -
Enable option 82 supporting
on the DHCP relay agent
dhcp relay information
enable
Required
By default, this function is
disabled
Configure the strategy for the
DHCP relay agent to process
request packets containing
option 82
dhcp relay information
strategy { drop | keep |
replace }
Optional
By default, the replace policy
is adopted