Figure 31 DHCP relay agent operation
DHCP relay agent support for Option 82
Option 82 records the location information about the DHCP client. It enables the administrator to
perform the following tasks:
•
Locate the DHCP client for security and accounting purposes.
•
Assign IP addresses in a specific range to clients.
For more information about Option 82, see
If the DHCP relay agent supports Option 82, it handles DHCP requests by following the strategies
described in
If a response returned by the DHCP server contains Option 82, the DHCP relay agent removes the
Option 82 before forwarding the response to the client.
Table 4 Handling strategies of the DHCP relay agent
If a DHCP request
has...
Option 82
No Option 82
DHCP relay agent configuration task list
Tasks at a glance
(Required.)
(Required.)
(Required.)
(Optional.)
Configuring the DHCP relay agent security functions
Table
4.
Handling
strategy
Drop
Keep
Replace
N/A
Enabling DHCP
Enabling the DHCP relay agent on an interface
Specifying DHCP servers on a relay agent
"Relay agent option (Option
The DHCP relay agent...
Drops the message.
Forwards the message without changing Option 82.
Forwards the message after replacing the original Option 82 with
the Option 82 padded according to the configured padding format,
padding content, and code type.
Forwards the message after adding Option 82 padded according to
the configured padding format, padding content, and code type.
67
82)."