Dhcp Snooping Support For Option 82; Dhcp Snooping Configuration Task List - 3Com Baseline 2928 PWR Plus User Manual

Table 3-1 Roles of ports
Device
Switch A GigabitEthernet 1/0/1
GigabitEthernet 1/0/3
Switch B and GigabitEthernet
1/0/4
Switch C GigabitEthernet 1/0/1

DHCP Snooping Support for Option 82

Option 82 records the location information of the DHCP client. The administrator can locate the DHCP
client to further implement security control and accounting. For more information, refer to
Option 82.
If DHCP snooping supports Option 82, it will handle a client's request according to the contents defined
in Option 82, if any. The handling strategies are described in the table below.
If a reply returned by the DHCP server contains Option 82, the DHCP snooping device will remove the
Option 82 before forwarding the reply to the client. If the reply contains no Option 82, the DHCP
snooping device forwards it directly.
If a client's requesting
message has...
Option 82
no Option 82

DHCP Snooping Configuration Task List

Complete the following tasks to configure DHCP snooping:
Task
Enabling DHCP
Snooping
Configuring DHCP
Snooping
Functions on an
Interface
Untrusted port
Handling
strategy
Drop
Keep
Replace
—
Required
By default, DHCP snooping is disabled.
Required
Specify an interface as trusted and configure DHCP snooping to support
Option 82.
By default, an interface is untrusted and DHCP snooping does not support
Option 82.
You need to specify the ports connected to the authorized 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.
Trusted port disabled from
recording binding entries
GigabitEthernet 1/0/3
GigabitEthernet 1/0/1
GigabitEthernet 1/0/3 and
GigabitEthernet 1/0/4
The DHCP snooping device will...
Drop the message.
Forward the message without changing Option 82.
Forward the message after replacing the original Option
82 with the Option 82 padded in normal format.
Forward the message after adding the Option 82
padded in normal format.
Remarks
3-3
Trusted port enabled to
record binding entries
GigabitEthernet 1/0/2
GigabitEthernet 1/0/2
GigabitEthernet 1/0/2
Introduction to