What is Network?

A network or communication network is a system of interconnected communication devices that can communicate with one another and share information. Therefore computer network can be defined as:

A system in which more than one computers or large number of computers are interconnected together, communicate freely with one another and share information is called computer network.

A network can be internal to an organization or span the world by connecting itself to the internet. In computer network, network operating system is used that controls and co-ordinates the activities of computers that are connected to the network. The example of these operating systems are: windows NT, UNIX, and Novell etc.

Types of Network

Networks are of three types. These are:

• Local Area Network (LAN)
• Wide Area Network (WAN)
• Metropolitan Area Network (MAN)

Local Area Network

A local area network is a network system in which computers are interconnected in a limited geographical area, such as network of computers in college computer laboratory or network of computers in office building etc.

Wide Area Network

A wide area network is a network system that covers a large geographical area such as different cities of country or different countries of the world. In WAN telephone lines, satellites, microwave, fiber optic etc. are used as transmission media. If you enjoy learning about computer networks and want to become an IT professional, a CCNA Training Course might be right for you."

Metropolitan Area Network

A Metropolitan area Network is a network system that covers area of a single city. Usually, MAN connects more than one LANS in a city or town and covers a smaller geographical area than a WAN. The cable television, telephone companies or local corporations use MAN.

Internet

The internet is a worldwide collection of networks that connects millions of computers, business, government agencies, educational institutions. It is a global network and source of information. Information can be communicated from one country to another through internet. More than two and half billion people around the world use the internet daily for different purposes. For example, to communicate with other people around the world, access information and latest news around the world. The computers are the main source through which information can be electronically sent and received from one location to another.

TCP/IP

In this protocol data transmission is managed by dividing the data into different pieces called packets. Each packet of data contains a part of actual data, source computer address, destination address, and information for reassembling data at destination computer. These packets of data travel along the fastest available path in the network. This type of data transmission is called packet switching and is used in internet communication.

IP Addressing

IP stands for internet protocol. Basically it is a unique identifier for a computer on the internet. It is numerical address with four numbers separated with dots and the format of an IP address is a 32-bit.Each number can be start from 0 and ends with 255. For example  IP address looks like this: 131.200.1.1

Every computer on the internet using unique IP address and this IP address can be static and dynamic. A server has a static IP address that does not change. When a computer dialing internet through modem then that computer has a IP address that is assigned by the local ISP. Your local ISP assigned you unique IP address for each session and it may be different each time.

What is Packets?

The transfer of data from one place to another place in the form of digital signals and this data is broken into small data segment before being transmitted from one computer to another computer. These small data segments are called packets. Each packets contains the information about its source and destination (sender's and receiver's information). A normal packets size between 1000 to 1500 bytes. The packets send to its destination using best possible path and this makes a network more efficient.

Network Devices

Digital Modem

The modem that is used to send and to receive data to and from a digital telephone line is called digital modem. ISDN modem and DSL modem are the best example of digital modem. These modem are used to send and receive the digital data to and from the digital line, So there is no need to convert to analog signals because digital lines already use the digital signals.

Bridge

It is an electronic device that connects two same type of networks and control the traffic between them. A bridge basically split an overloaded network into two separate network for reducing the amount of traffic on each segment and increase the performance of each network. A bridge looks at the information in each packet header and forwards data from one LAN to another.

Router

An electronic device that connects many computers together and transmits data to its correct destination using the available path on the network is called router. It stores the information of each node on the network and to use these information to transfer date between nodes.

Routable Protocols

There are not all protocols works with routers. Routable protocols are

• IP
• IPX
• OSI
• DECnet
• XNS

Like a bridge, a router looks at each packet's header to determine the destination of packet and thus reach its destination. Some routers also have built-in antivirus protection. Similarly, some routers also support wireless communication

Type of Routers

Static Router.

An administrator manually set up the router path and configuration of static router.

Dynamic Router.

A dynamic router automatically find the path to its destination with minimal configuration.

Gateway

A gateway is an electronic device that can perform logical function. A gateway is a device or system (because it may be a hardware or software) that connects two or more networks to share their information from one to the other. Packets from different networks have different type of information in their headers, and information in different format. The gateway can take a packet from one type of network, read the header, and then encapsulates the entire packet into a new one, adding a header that is understood by the network.