Dhcp Relay Interface Settings - D-Link xStack DGS-3420 Series Reference Manual

xStack® DGS-3420 Series Layer 2 Managed Stackable Gigabit Switch Web UI Reference Guide
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.
The Implementation of DHCP Relay Agent Information Option 82
The 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.
Circuit ID sub-option format:
1 Sub-option type
2 Length
3 Circuit ID type
4 Length
5 VLAN: The incoming VLAN ID of DHCP client packet.
6 Module: For a standalone switch, the Module is always 0; for a stackable switch, the Module is the Unit ID.
7 Port: The incoming port number of the DHCP client packet, the port number starts from 1.
Remote ID sub-option format:
1 Sub-option type
2 Length
3 Remote ID type
4 Length
5 MAC address: The Switch's system MAC address.

DHCP Relay Interface Settings

Users can set up a server, by IP address, for relaying DHCP information to the Switch. The user may enter a
previously configured IP interface on the Switch that will be connected directly to the DHCP client using this
Figure 9-2 Circuit ID Sub-option Format
Figure 9-3 Remote ID Sub-option Format
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