Prerequisites; Configuring Dhcp Snooping To Support Option 82 - 3Com 4510G Configuration Manual

You need to specify the ports connected to the valid DHCP servers as trusted to ensure that
DHCP clients can obtain valid IP addresses. The trusted port and the port connected to the DHCP
client must be in the same VLAN.
You can specify Layer 2 Ethernet interfaces and Layer 2 aggregate interfaces as trusted ports.
For details about aggregate interfaces, refer to Link Aggregation Configuration in the Access
Volume.
If a Layer 2 Ethernet interface is added to an aggregation group, DHCP snooping configured on
the interface will not take effect. After the interface quits from the aggregation group, DHCP
snooping will be effective.
Do not add an untrusted Layer 2 Ethernet interface to an aggregation group.
Configuring both the DHCP snooping and selective QinQ function on the switch is not
recommended because it may result in malfunctioning of DHCP snooping.

Configuring DHCP Snooping to Support Option 82

Prerequisites

You need to enable the DHCP snooping function before configuring DHCP snooping to support Option
82.
Configuring DHCP Snooping to Support Option 82
Follow these steps to configure DHCP snooping to support Option 82:
Enter system view
Enter interface view
Enable DHCP snooping to support
Option 82
Configure the handling strategy for
requesting messages containing Option
82
To do... Use the command...
system-view
interface interface-type
interface-number
dhcp-snooping
information enable
dhcp-snooping
information strategy
{ drop | keep | replace }
8-5
Remarks
—
—
Required
Disabled by default.
Optional
replace by default.