D-Link DES-3528 - xStack Switch - Stackable Reference Manual page 285

xStack® DES-3528/DES-3552 Series Layer 2 Stackable Fast Ethernet Managed Switch Web UI Reference Guide
DHCP Relay Option 82
State
DHCP Relay Agent
Information Option 82
Check
DHCP Relay Agent
Information Option 82
Policy
DHCP Relay Agent
Information Option 82
Remote ID
DHCP Relay Option 60
State
DHCP Relay Option 61
State
Click the Apply button to accept the changes made for each individual section.
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, users may configure a client with the option 82 field. In this situation,
disable the information check feature so that the Switch does not remove the option 82 field from
the packet. Users may 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.
given DHCP packet.
This field can be toggled between Enabled and Disabled using the pull-down menu. It
is used to enable or disable the DHCP Relay Agent Information Option 82 on the
Switch. The default is Disabled.
Enabled –When this field is toggled to Enabled, the relay agent will insert and remove
DHCP relay information (option 82 field) in messages between DHCP servers and
clients. 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 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.
Disabled- When the field is toggled to Disabled, 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.
This field can be toggled between Enabled and Disabled using the pull-down menu. It
is used to enable or disable the Switch's ability to check the validity of the packet's
option 82 field. The default is Disabled.
Enabled – When the field is toggled to Enabled, 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.
This field can be toggled between Replace, Drop, and Keep by using the pull-down
menu. It is used to set the Switch's policy for handling packets when the DHCP Relay
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.
Enter the DHCP Relay Agent Information Option 82 Remote ID. Tick the Default
check box to use MAC address as the Remote ID.
Use the drop-down menu to enable or disable the use of the DHCP Relay Option 60
State feature.
Use the drop-down menu to enable or disable the use of the DHCP Relay Option 61
State feature.
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