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DES-3200-10/18/28/28F Layer 2 Ethernet Managed Switch User Manual
check and policy settings will have no effect.
DHCP Relay Agent
Information Option 82
Check
This field can be toggled between Enabled and Disabled using the pull-down menu. It is
used to enable or disable the Switches ability to check the validity of the packet’s option 82
field.
Enabled – When the field is toggled to Enable, the relay agent will check the validity of the
packet’s option 82 field. If the switch receives a packet that contains the option-82 field from
a DHCP client, the switch drops the packet because it is invalid. In packets received from
DHCP servers, the relay agent will drop invalid messages.
Disabled - When the field is toggled to Disabled, the relay agent will not check the validity of
the packet’s option 82 field.
DHCP Relay Agent
Information Option 82
Policy
This field can be toggled between Replace, Drop, and Keep by using the pull-down menu.
It is used to set the Switches policy for handling packets when the DHCP Agent Information
Option 82 Check is set to Disabled. The default is Replace.
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.
DHCP Relay Agent
Information Option 82
Remote ID
This field is for you to enter the remote ID. Tick Default to use the Switch’s system MAC
address as the remote ID.
Click Apply to implement any changes that have been made.
NOTE: If the Switch receives a packet that contains the option-82 field from a DHCP
client and the information-checking feature is enabled, the switch drops the packet
because it is invalid. However, in some instances, you might configure a client with the
option-82 field. In this situation, you should disable the information-check feature so
that the switch does not remove the option-82 field from the packet. You can configure
the action that the switch takes when it receives a packet with existing option-82
information by configuring the DHCP Agent Information Option 82 Policy.
The Implementation of DHCP Information Option 82 on the Switch
The config dhcp_relay option_82 command configures the DHCP relay agent information option 82 setting of the
switch. The formats for the circuit ID sub-option and the remote ID sub-option are as follows:
NOTE: For the circuit ID sub-option of a standalone switch, the module field is always
zero.
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