D-Link DES-3550 Command Line Interface Reference Manual page 183

config dhcp_relay option_82
Purpose Used to configure the DHCP relay agent option 82 of the Switch.
Syntax
config dhcp_relay option_82 {state [enable | disable] | check [enable | disable]
| policy [replace | drop | keep] }
Description This command is used to configure the use of the Relay Agent Information Option or
option 82 as defined in RFC 3046.
Parameters state – Used to specify use of Option 82 as described in RFC 3046. When enabled,
information is inserted into the DHCP request forwarded by the relay agent (the
Switch) to the DHCP/BOOTP server. The inserted information may be used by the
DHCP server for policy implementation such as restrictions applied to IP address
assignment. The DHCP server responds with a unicast reply to the forwarded
request back to the Switch. Upon reception, the Switch verifies the option 82 data
and removes it from the option 82 field before forwarding it to the port where the
initial request originated.
check – Used to specify a validity check of the option 82 field when enabled. If the
option 82 field is determined invalid the DHCP request is dropped.
policy - Used to specify a policy implementation in the option 82 field when enabled.
The policy instructions are one of the following:
Restrictions Only administrator-level users can issue this command.
DES-3550 Layer 2 Fast Ethernet Switch
enable - When the option 82 state is enabled the relay agent will insert and
remove DHCP relay information (option 82 field) in messages between DHCP
server and client.
disable- This will disable the option 82 state if it has previously been enabled.
enable – If the option 82 check is enabled, a validity check is applied to the
option 82 field.
disable - This will disable the option 82 check if it has previously been enabled.
replace- The option 82 field will be replaced if the option 82 field already exists in
the packet received from the DHCP client.
drop- The packet will be dropped if the option 82 field already exists in the packet
received from the DHCP client.
keep- The option 82 field will be retained if the option 82 field already exists in
the packet received from the DHCP client.
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