Computer Networking
Local Area Network
Topology

How does a LAN work?

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2015-07-16 18:10:21

"LANs" id="LANs">LANs

  • 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

    LANs.

  • 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

lan stands for the local area network .ie if you are connecting

you comouter or devices (printer ) in a specific limited area ie

locally .

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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

redirector.

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:

drive.

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

Internet.

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ANSWER

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.

User Avatar
Wiki User
2014-12-18 16:17:08

A LAN network is local area network . LAN is used at a smaller

level . LAN is used in small organizations.


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