Chapter 4: Web configuration
NS3562-8P-2S User Manual
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from attached clients on DHCP services, such as IP Spoofing, Client Identifier
Spoofing, MAC Address Spoofing, and Address Exhaustion.
The DHCP option 82 enables a DHCP relay agent to insert specific information into a
DHCP request packets when forwarding client DHCP packets to a DHCP server and
remove the specific information from a DHCP reply packets when forwarding server
DHCP packets to a DHCP client. The DHCP server can use this information to
implement IP address or other assignment policies. Specifically the option works by
setting two sub-options:
• Circuit ID (option 1)
• Remote ID (option 2)
The Circuit ID sub-option includes information specific to which circuit the request came
in on.
The Remote ID sub-option was designed to carry information relating to the remote
host end of the circuit.
The definition of Circuit ID in the switch is 4 bytes in length and the format is "vlan_id"
"module_id" "port_no". The parameter of "vlan_id" is the first two bytes represent the
VLAN ID. The parameter of "module_id" is the third byte for the module ID (in
standalone switch it always equal 0, in switch it means switch ID). The parameter of
"port_no" is the fourth byte and it means the port number.
After enabling DHCP snooping, the switch monitors all the DHCP messages and
implement software transmission.
The page includes the following fields:
Object
Description
State
Set the option2 (remote ID option) content of option 82 added by
DHCP request packets.
Default
is the default VLAN MAC format.
User-Define
is the remote-id content of option 82 specified by
users
Buttons
• Click
Apply
to apply changes.
Option82 port setting
This function is used to set the retransmitting policy of the system for the received
DHCP request message which contains option82.