D-Link DGS-3700-12 User Manual page 253

(0-65535) of the DHCP packet. If a non-zero value is entered, the Switch will use that value, along with the
hop count to determine whether to forward a given DHCP packet.
DHCP Relay This field can be toggled between Enabled and Disabled using the pull-down menu. It is used to
Option 82 State enable or disable the DHCP 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 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.
Disabled – If 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 This field can be toggled between Enabled and Disabled using the pull-down menu. It is used to
Agent enable or disable the Switches ability to check the validity of the packet's option 82 field.
Information
Enabled – When the field is toggled to Enable, the relay agent will check the validity of the
Option 82 Check
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 This field can be toggled among Replace, Drop, and Keep by using the pull-down menu. It is used
Agent to set the Switches policy for handling packets when the DHCP Agent Information Option 82
Information Check is set to Disabled. The default is Replace.
Option 82 Policy
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 Enter a DHCP relay agent information option 82 remote ID or tick the Default check box.
Agent
Information
Option 82
Remote ID
DHCP Relay This function enables or disables the DHCP option 60 state. When option 60 is enabled, if the
Option 60 State packet does not have option 60, then the relay servers cannot be determined based on option 60.
The relay servers will be determined based on either option 60 or per IPIF configured servers. If
the relay servers are determined based on option 60, then the IPIF configured servers will be
ignored. If the relay servers are not determined by option 60 then the IPIF configured servers will
be used to determine the relay servers.
DHCP Relay
This function enables or disables the DHCP option 61 state. When option 61 is enabled, if the
Option 61 State
packet does not have option 61, then the relay servers cannot be determined based on option 61.
The relay servers will be determined based on option 61 and the IPIF configured servers will be
ignored. If the relay servers are not determined either by option 60 or option 61, then IPIF
configured servers will be used to determine the relay servers.
Click Apply to implement any changes that have been made.
DGS-3700-12/DGS-3700-12G Series Layer 2 Gigabit Ethernet User Manual
251