Network

COMPUTER NETWORKING

A network is a collection or a group of people interacting and sharing information with each other, So in the same way , a Computer network is a group of computer that interacts and share information with each other , connected by some communication links such as wires, cable or wirelessly. It is all about transmitting message from sender to receiver and vice-versa. A computer network can be wired and wireless.

There are various mediums to make a wired network. These are:

i)  Twisted Pair Wires

ii) Copper Wire or Coaxial Cable

iii) Fibre-Optic Cables

Mediums to form a wireless network are:

i) Radio Waves

ii) Terrestrial Communication

iii) Communication Satellites

There are various kinds of Networks. These are:

i) Personal Area Network (PAN):

A Personal Area Network (PAN) is a computer network that is used to transfer messages between a computer and other technological devices that belongs to one person only.  Example of such devices are a laptop or desktop, fax machine, Personal Digital Assistance (PDA) or Palmtop computer, scanner , printer etc. The range of a PAN is around 10 metres. 

ii) Local Area Network (LAN):

A  Local Area Network (LAN) is a computer network that is set-up within a home, college, institution, college and there nearby buildings. The connected computers are called nodes of this computer network. The wired LAN can be formed using an Ethernet cable. The range of a LAN is about 100-150 metres.

Wireless LAN can be formed using the WI-FI slots in your computers.

iii) Metropolitan Area Network (MAN):

A Metropolitan Area Network (MAN) is a computer network that is set-up for a whole city or a very large area. MAN can cover a region of almost 30-40 kilometres. 

iv) Wide Area Network(WAN):

A Wide Area Network(WAN) is a computer network that is set-up along a big area such as a WAN covering two or more cities, a country, a continent. The best example of WAN is Internet.

Now after defining the network analogies, we should move on to the Internet and should look into some aspects of Internet.

When we talk about internet , we all have some very basic questions about internet. So here are the answers to your questions..

Ques 1. What is an Internet ?

Internet is a collection of computers i.e. it is a network of networks in which million of computer are connected and interacting with each other. People are connected to the Internet from all over the world through different devices such as desktops, laptops, smartphones, tablets etc. These all devices in networking are called as hosts or end users or nodes. According to a survey conducted in 2011, more than 2 billion hosts were connected to Internet.

Ques 2. How do different end users communicate with each other over computer networks?

Now directly before answering your question, I want to ask something from you. Suppose when you want to ask time from a stranger. How do you do it. You first say "Hi" (Greet message) to initiate the communication, then he will reply you with "Hi"( a message that you will take as an indication, that the receiver is willing to communicate and you can proceed to ask time). Or the other replies could be "Don't bother me" or "I don't understand your language", indicates the unwillingness to communicate. So you would not ask time.

These were the human protocols, that before initiating you should say a "Hi" or "Hello"(or at-least your manners), then the reply from the receiver , that will indicate you, whether you should proceed with asking time or not.

Same is the procedure in computer networks except that here the messages are exchanged between systems and machines and their hardware and software. The requesting node will send a requesting message to the receiver, then receiver will send a reply message, whether he is ready to communicate or not, and the communication will move on. This is often called as a 3-way handshake, that we will discuss in later articles. The figure below will make you understand this more clearly.

This whole procedure is governed by certain set of rules , that are called as protocols.

Ques 3. What are the different ways of sending data ?

The message or the data is called as packet in computer networks. So sending of packets can be done be done in 2 ways. Circuit switching and Packet Switching.

Ques 4. What are protocols?

A protocol defines the type, method and the order of the messages exchanged between the sender and the receiver node, and the actions to be taken after the transmission or the receipt of the message.

Ques 5. What are the problems that occur after setting up a network?

There are certain problems that we have to take into account to have proper transmission of message from sender to receiver. There can be Noise, various delays while transmitting, interference from outside etc.

These are Transmission Delay, Queuing Delay, Processing Delay, Propagation Delay.

Ques 6. How many protocol Layering are there?

There are basically two models of protocol layering .One is said to be Open Systems Interconnection(OSI ) layer model and the other is TCP/IP model.

In OSI model, there are 7 layers while in TCP/IP model, there are 5 layers of protocols.

Ques 7. Is there any threat to our networks to our hosts?

Yes, there are lots of threats engaged when you are connected to an Internet. There are two types of attacks, Active and Passive attacks. These attacks can include Denial of Service attacks, virus attacks, infrastructure attacks etc.