User’s Manual of WGR-500-4P and WGR-500-4PV
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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) and Remote ID (option2). The Circuit ID sub-option
is supposed to include 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 stackable switch
it means switch ID). The parameter of "port_no" is the fourth byte and it means the port number.
The Remote ID is 6 bytes in length, and the value is equal the DHCP relay agents MAC address.
DNS
DNS is an acronym for
D
omain
N
ame
S
ystem. It stores and associates many types of information with
domain names. Most importantly, DNS translates human-friendly domain names and computer
hostnames into computer-friendly IP addresses. For example, the domain name www.example.com
might translate to 192.168.0.1.
DoS
DoS is an acronym for
D
enial of
S
ervice. In a denial-of-service (DoS) attack, an attacker attempts to
prevent legitimate users from accessing information or services. By targeting at network sites or network
connection, an attacker may be able to prevent network users from accessing email, web sites, online
accounts (banking, etc.), or other services that rely on the affected computer.
E
Ethernet Type
Ethernet Type, or EtherType, is a field in the Ethernet MAC header, defined by the Ethernet networking
standard. It is used to indicate which protocol is being transported in an Ethernet frame.
F
FTP
FTP is an acronym for
F
ile
T
ransfer
P
rotocol. It is a transfer protocol that uses the Transmission Control
Protocol (TCP) and provides file writing and reading. It also provides directory service and security
features.
H
HTTP
HTTP is an acronym for
H
ypertext
T
ransfer
P
rotocol. It is a protocol that used to transfer or convey
information on the World Wide Web (WWW).
