Networking tutorial for beginer and advanced user

What is OSI MODEL?

1. Open System Interconnection model is fundamental to all communications between network devices.
2. Developed in 1974 by ISO after the American department of defense began yusing the TCP/IP Suite of protocols
3. Finally adopted in 1977. It is not the theoretical model for how communication takes place between network devices

7 Layer model

A layer is a collection of conceptually similar functions that provide services to the layer above it and receives service from the layer below it

Application, Presentation, Session, Transport, Network, Data Link, Physical

Layers

1. Each layer is separate and independent
2. Each layer has its own function but also provides a service to those layers above and below itself
3. When communicating, each OSI layers talks with the same layer in the other device for example the application layer of device A communicates with the Application Layer of Device B, by passing the data through the other layers.
4. The Application layer of each device is not concerned with how the other layers are functioning, but it does rely on them to do their job.

Layer layer OSI model and its work

How data does flows

When data is sent from the application on the source computer it goes step by step as bellow.

1. Data in the form of packet moves down through the layers of OSI layer model starting from Application layer and end at Physical Layer.
2. When Data reach to physical layer Data is ready to send over cable or medium
3. At physical layer data bits may be analogue, digital, in the form of electrical signal or radio waves.
4. When data is transmitted to destination device it travels up through the layer from physical layer to application layer of OSI Model.
5. As data moves from one layer to another layer some additional information get added as header or trailers in data and addition of this additional information is known as encapsulation and data goes encapsulated.
6. Due to this encapsulation data does not change. here is a graphical example of data encapsulation.

In next post I will explain each layer and there job role in OSI model

 

Introduction to network

Network is collection of computers connected to each other. It allows the computer to communicate with each other. Computers connected in network can share resources which include information, software and peripheral device.

Advantage of Network

It enables users to share hardware like scanner and printers. This reduces costs by reducing the number of hardware item bought. It allow users to access data stored on other computers. It can allow user to run program installed on other computer in network.

Disadvantage of network

Accessing anything over network is slower then accessing the same thing on your own computer. Network is more complex so more problem to handle that.

History of computer Networks

The Advanced Research Projects Agency Network (ARPANET) Developed by United states Department of Defense was the world’s first operational network, and the predecessor of the global internet.

It was established in 1969. ARPANET served as a test bed for new networking technologies, Linking many universities and research centers.

The first two nodes that formed the ARPANET were UCLA (university of California at loss Angeles) and the Stanford Research Institute, followed shortly thereafter by the University of Utah

Types Of computer Networks

There are different types of computer network for different uses and purposes here are a detail of few of them that are most important to learn.

LAN

A LAN is local Area Network. This would include networks where the computers are relatively close together. LANs would be within the same office, a single building or several building closer to each other.

WAN

WAN covers a large geographical area. WANs are mostly used lease line or public phone lines as there back bone. It is also known as Wide Area Network

W LAN

A LAN based on WiFi wireless network technology is known as WLAN or Wireless Local Area Network. WLAN provide wireless network connectivity to laptop and desktop computers.

MAN

Metropolitan Area Network - a network spanning a physical area larger than a LAN but smaller than a WAN, such as a city. A MAN is typically owned and operated by a single entity such as a government body or large corporation.

Campus Area Network - a network spanning multiple LANs but smaller than a MAN, such as on a university or local business campus.

All the communication over a Network work on a well adopted model that is known as OSI model

I will talk about OSI model in my next post

I bought this domain www.techraga.com  almost six month back but I was not able to decide what I should write here or how I should start it. After a long time my students told me I should write about Networking and I should teach that via my website.

So I would start writing about basics of networking, than I would go ahead with bigger things.

First post would be how to make a network cable and in this post I would include basics of making a network cable and logics for that.

Thanks
AP Dubey