How does a LAN work?
- A Local Area Network is a small network which is usually
contained within one building or campus. It is usually a private
network, unlike the public internet. An Administrator in charge
controlls file sharing, access and many other factors. LANs can be
connected to public networks like the Internet, with some
precautions (against hackers, viruses etc). Usually a
firewall/proxy server/router acts as the gateway between the LAN
and the Public Network. A popular wired LAN technology is the
Ethernet (Sometimes called IEEE 802.3). These days Wireless LANs
are becoming popular. They are collectively known as IEEE 802.11
- I could spend hours going into detail about this question, but
I won't. Basically the proxy server will go to internet to pull a
webpage for the client requesting it. It also will store a copy of
this page (cache) for future requests. Another function of the
proxy is that is hides the clients IP address from the "outside
world", and uses its own. Therefore, the webmaster of the webpage
cant see the IP of the client requesting the page because in
actuallity the proxy is requesting the page.
lan stands for the local area network .ie if you are connecting
you comouter or devices (printer ) in a specific limited area ie
A LAN allows certain computers on the network to offer their
resources (hard disks, floppy disks, CD-ROMs, Printers, Modems,
etc.) for use by other computers on the network as if they were
their own. Computers that offer resources are called Servers.
Computers called Workstations can attach the resources
(typically hard disks and printers) offered by servers as if they
were their own. For instance, at AA Company, computer #1 has a C:
hard disk and a D: CD-ROM. Computer #2 has a C: hard disk and a D:
CD-ROM, but computer #2 also attaches computer #1's C: drive as
it's own F: drive. To the user of computer #2 it looks as if drive
F: is in his own computer. He can use files and programs from the
F: drive just as he can from his own C: drive. The network software
module that performs this slight of hand is called the
A computer can be both a Server and Workstations at the same
time, in which case it is called a Peer. Networks without dedicated
servers are called peer-to-peer networks. Networks with one or more
dedicated servers are called server based networks even though they
may also have peers on them.
Back to our example. The network computers #1 and #2 are on has
a server, computer #3. Computers #1 and #2 each have a copy of an
accounting program on them, but both read and write accounting data
to their G: drive, which is actually C: on computer #3. The tape
backup unit is on computer #3 and backs up all the accounting data
for all the computers every night by backing up its own C:
When computers #1 and #2 are using the accounting software that
software is running in their own memories. The server is not
involved at all except to offer its hard disk for data storage.
This server is called a file server.
Since this is a Windows accounting package it is big and slow
and swaps to disk a lot, so each computer has it installed on its
own hard disk to get decent performance. In the days of small fast
DOS programs, workstations would also load the program from the
server, so it only had to be installed once in one place.
When computers #1 and #2 do sorted reports, every record has to
be read from the server and sorted in the memory of the workstation
and written back to temporary files on the server. This causes a
lot of network traffic on a larger network.
Lets say AA Company grows a lot and now still has computers #1,
#2 and server #3 but has added additional workstations #4 through
#29 - and lots of users of the accounting software. all that
network traffic causes the network to get really bogged down and
users start to complain.
What AA Company does now is ditch that Windows accounting
package and install a new multiprocesor Compaq server running
Windows NT. The new accounting package uses the Oracle database
program to store its data at the server. This new package actually
runs on the server (which is now called an application server
because it has applications programs running on it). The
workstations just have a client program that asks for records and
has input and viewing screens. If a client asks for a sorted report
all the work is done at the server, cutting network traffic way
down. This is called a Client Server network.
Meanwhile, across town, BX Company started with its accounting
on a Xenix host computer with some "green screen" terminals wired
to it (instead of PCs like AA Company used). There was no network
at all, just a lot of serial cables connecting dumb terminals and
printers to the host computer.
As it grew, BX upgraded to a Unix host computer and added some
PCs that were also wired back to the host and ran terminal
emulation software so they could act as terminals to use the
accounting. Some of the PCs also got their own printers, which also
act as slave printers to the Unix box. Still no network.
Finally, BX Company needed to exchange marketing and project
files among the PCs, so they installed a peer-to-peer network
connecting all the PCs, and included their big honk'n Sun
Enterprise Unix box in the network too. The PCs dumped the terminal
emulation package and use telnet which allows them to act as
terminals over the network - no more serial cables. Later they add
a Linux box to the network to act as a file server, as an Intranet
Web server and as a firewall for their DSL connection to the
LAN is a Huge topic and to know how it works you need to
understand what it features are and in what ways a LAN can work
like it can work in a Ring Network,Bus Network...It can be used
With WAN from a larger to cover a small area,The transmission can
be provided by the Token Passing Technique or the Carrier Sense
Multiple Access/Collision Detection Technique...The OSI
Layers...The hardwire and the software Required...and so On.
I think you can start from the basics to have a better
understanding and don't miss out anything.Search in Google or
better buy a Book on Networking.