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DGS-3400 Series Layer 2 Gigabit Managed Switch CLI Manual
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config dhcp_relay option_82 state
Purpose Used to configure the state of DHCP relay agent information option 82 of the switch.
Syntax
config dhcp_relay option_82 state [enable | disable]
Description This command is used to configure the state of DHCP relay agent information option 82
of the switch.
Parameters enable – When this field is toggled to Enabled the relay agent will insert and remove
DHCP relay information (option 82 field) in messages between DHCP server and client.
When the relay agent receives the DHCP request, it adds the option 82 information, and
the IP address of the relay agent (if the relay agent is configured), to the packet. Once the
option 82 information has been added to the packet it is sent on to the DHCP server.
When the DHCP server receives the packet, if the server is capable of option 82, it can
implement policies like restricting the number of IP addresses that can be assigned to a
single remote ID or circuit ID. Then the DHCP server echoes the option 82 field in the
DHCP reply. The DHCP server unicasts the reply to the back to the relay agent if the
request was relayed to the server by the relay agent. The switch verifies that it originally
inserted the option 82 data. Finally, the relay agent removes the option 82 field and
forwards the packet to the switch port that connects to the DHCP client that sent the
DHCP request.
disable – If the field is toggled to disable the relay agent will not insert and remove DHCP
relay information (option 82 field) in messages between DHCP servers and clients, and
the check and policy settings will have no effect.
Restrictions Only Administrator and Operator-level users can issue this command.
Example usage:
To configure DHCP relay option 82 state:
DGS–3426:5#config dhcp_relay option_82 state enable
Command: config dhcp_relay option_82 state enable
Success.
DGS–3426:5#
config dhcp_relay option_82 check
Purpose Used to configure the checking mechanism of DHCP relay agent information option 82 of
the switch.
Syntax
config dhcp_relay option_82 check [enable | disable]
Description This command is used to configure the checking mechanism of DHCP/BOOTP relay
agent information option 82 of the switch.
Parameters enable – 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.
disable – When the field is toggled to disable, the relay agent will not check the validity of
the packet’s option 82 field.
Restrictions Only Administrator and Operator-level users can issue this command.
Example usage:
To configure DHCP relay option 82 check:
