How does a LAN work?

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.
A LAN network is local area network . LAN is used at a smaller level . LAN is used in small organizations.