D-Link DGS-3620-28PC-SI, Руководство по эксплуатации продукта

Страница: 400 / 502

xStack® DGS-3620 Series Managed Switch Web UI Reference Guide
390
DHCP Relay Option 82
State
This field can be toggled between
Enabled
and
Disabled
using the drop-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.
DHCP Relay Agent
Information Option 82
Check
This field can be toggled between
Enabled
and
Disabled
using the drop-down
menu. It is used to enable or disable the Switch’s ability to check the validity of the
packet’s option 82 field.
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.
DHCP Relay Agent
Information Option 82
Policy
This field can be toggled between
Replace, Drop,
and
Keep
by using the drop-
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.
DHCP Relay Agent
Information Option 82
Remote ID
Enter the DHCP Relay Agent Information Option 82 Remote ID.
DHCP Relay Option 60
State
Use the drop-down menu to enable or disable the use of the DHCP Relay Option
60 State feature.
DHCP Relay Option 61
State
Use the drop-down menu to enable or disable the use of the DHCP Relay Option
61 State feature.
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 drop 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.