Chapter 6: Glossary
Chapter 6: Glossary
ARP (Address R
ARP is a TCP/IP p
recognized in the
A host wishing to obtain a physical ad dress broad casts an ARP request onto the TCP/IP network.
The host on the network that has the IP address in the request then replies with its physical
hardware address.
Inverse ARP (In-ARP), on the other hand, is used by a host to discover its IP address. In this case,
the host broadcasts its physical add ress and a RARP server replies with the host's IP addre s s.
DHCP (Dynamic Host Configuration Protocol)
When operates as a DHCP server, the ADSL Ro uter assign IP addresses to the client PCs on the
LAN. The client PCs “leases” the se Privat e IP addresses for a use r-defined a m ount of time. After
the lease time expires, the private IP address is made available for assigning to other network
devices.
The DHCP IP address can be a single, fixed public IP address, an ISP assigned public IP address,
or a private IP address.
If you enable DHC
to the NAT IP add
translated into a p y this, the client PCs are able to access the Internet.
LAN (Local a
A LAN is a comput uilding or floor of a
building. A WAN, o r network or the Internet.
The Ethernet side
10Base-T interfac LAN port. More than one computers, such as
server or prin AN.
The DSL port of th ts PPP or RFC
1483 connecting t
NAT (Netwo
NAT is an Internet ork to a public IP address,
either a static or dynami s. It
also enables a com
If the IP addresses given by your ISP are not enough for ea ch PC on the LAN and the ADSL
Router, you need to use NAT. With NAT, you make up a private IP network for the LAN and
assign an IP address from that netwo rk to each PC. One of some public addresses is config ured
and mapped to a private workstation address when accesses are made through the gateway to a
publi network.
For example, the ADSL Router is assign ed with the public IP add ress of 168.111.2.1. With NAT
enabled, it creates a Virtual LAN. Each PC on the Virtual LAN is assigned with a private IP
address with default value of 192.168.2.2 to 192.168.2.254. These PCs are not accessibl e by the
outside world but they can communicate with the outside world through the public IP 168.111. 2.1.
Private IP Address
Private IP addresses are also LAN IP addresses, but are considered “illegal” IP addresses to the
Internet. They are private to an enterprise while still permitting full network layer connectivity
between all hosts inside an enterprise as well as all public hosts of different enterprises.
esolution Protocol )
rotocol for mapping an IP address to a physical machine address that is
local network, such as an Ethernet add ress.
P server on a private IP address, a public IP address will have to be assigned
ress, and NAT has to be enabled so that the DHCP IP address can be
ublic IP address. B
Are Network) & WAN (Wide Area Network)
er network limited to the immediate area, u sually the same b
n the other hand, is an outside connection to anothe
of the ADSL Router is called the LAN port. It is a twisted-pair Ethernet
e. A hub can be connected to the
ter, can be connected through this hub to the ADSL Router and composes a L
e ADSL Router composes the WAN interface, which suppor
o another remote DSL device.
rk Address Translation) IP Address
standard that translates a private IP within one netw
c one. NAT provides a type of firewall by hiding internal IP addresse
pany to use more internal IP addresses.
c