INTRODUCTION TO INTERNET
The Internet is worldwide computer network that interconnects, million of computing devices throughout the world. Most of these devices are PC’s, and servers that store and transmit information such as web pages and e-mail messages. Internet is revolutionizing and enhancing the way we as humans communicate, both locally and around the globe. Everyone wants to be a part of it because the Internet literally puts a world of information and a potential worldwide audience at your fingertips.
The Internet evolved from the ARPANET (Advanced Research Projects Agency) to which other networks were added to form an inter network. The present Internet is a collection of several hundred thousand of networks rather than a single network. From there evolved a high-speed backbone of Internet access for sharing these of networks. The end of the decade saw the emergence of the World Wide Web, which heralded a platform-independent means of communication enhanced with a pleasant and relatively easy-to-use graphical interface.
World Wide Web is an example of an information protocol/service that can be used to send and receive information over the Internet. It supports:
The Internet evolved from the ARPANET (Advanced Research Projects Agency) to which other networks were added to form an inter network. The present Internet is a collection of several hundred thousand of networks rather than a single network. From there evolved a high-speed backbone of Internet access for sharing these of networks. The end of the decade saw the emergence of the World Wide Web, which heralded a platform-independent means of communication enhanced with a pleasant and relatively easy-to-use graphical interface.
World Wide Web is an example of an information protocol/service that can be used to send and receive information over the Internet. It supports:
- Multimedia Information (text, movies, pictures, sound, programs . . . ).
- Hyper Text Information (information that contains links to other information resources).
- Graphic User Interface (so users can point and click to request information instead of typing in text commands).
OBJECTIVES
After reading this article, you will be able to understand:
- Make classification of networks;
- understand two types of networking models;
- understand the concept of packet switching;
- understand how to access to the internet;
- list the services available on Internet; and
- understand how does the Internet works.
CLASSIFICATION OF NETWORKS:
There are different approaches to the classification of compute Networks. One such classification is based on the distance approach. In this section we will discuss such networks.
The networks can be classified into LAN, MAN and WAN networks. Here, we describe them into brief to understand the difference between the types of network.
Local Area Network (LAN)
LAN is a privately - owned computer networks confined to small geographical area, such as an office or a factory widely used to connect office PCs to share information and resources. In a Local area network two or more computers are connected by same physical medium, such as a transmission cable. An important characteristic of Local Area networks is speed. i.e. they deliver the data very fast compared to other types of networks with typical data transmission speed are 10-100 Mbps.
A wide variety of LANs have been built and installed, but a few types have more recently become dominant. The most widely used LAN system is the Ethernet system. Intermediate nodes (i.e. repeaters, bridges and switches) allow LANs to be connected together to form larger LANs. A LAN may also be connected to another LAN or to WANs and MANs using a “router”.
In summary, a LAN is a communications network, which is:
The networks can be classified into LAN, MAN and WAN networks. Here, we describe them into brief to understand the difference between the types of network.
Local Area Network (LAN)
LAN is a privately - owned computer networks confined to small geographical area, such as an office or a factory widely used to connect office PCs to share information and resources. In a Local area network two or more computers are connected by same physical medium, such as a transmission cable. An important characteristic of Local Area networks is speed. i.e. they deliver the data very fast compared to other types of networks with typical data transmission speed are 10-100 Mbps.
A wide variety of LANs have been built and installed, but a few types have more recently become dominant. The most widely used LAN system is the Ethernet system. Intermediate nodes (i.e. repeaters, bridges and switches) allow LANs to be connected together to form larger LANs. A LAN may also be connected to another LAN or to WANs and MANs using a “router”.
In summary, a LAN is a communications network, which is:
- local (i.e. one building or group of buildings)
- controlled by one administrative authority
- usually high speed and is always shared
LAN allows users to share resources on computers within an organization.
Metropolitan Area Network (MAN)
A MAN, basically a bigger versions of a LAN is designed to extend over an entire city. It may be single network such as a cable television network, or it may be a means of connecting a number of LANs into a large network so that resources may be shared for example, a company can use a MAN to connect the LANs in all of its offices throughout a city.
A MAN typically covers an area of between 5 and 50 km diameter. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of buildings
The MAN, its communications links and equipment are generally owned by either a consortium of users or by a single network provider who sells the service to the users. This level of service provided to each user must therefore be negotiated with the MAN operator, and some performance guarantees are normally specified.
A MAN often acts as a high-speed network to allow sharing of regional resources (similar to a large LAN). It is also frequently used to provide a shared connection to other networks using a link to a WAN.
Wide Area Network (WAN)
The term Wide Area Network (WAN) usually refers to a network, which covers a large geographical area, and use communications subnets (circuits) to connect the intermediate nodes. A major factor impacting WAN design and performance is a requirement that they lease communication subsets from telephone companies or other communications carriers. Transmission rates are typically 2 Mbps, 34 Mbps, 155 Mbps, 625 Mbps (or sometimes considerably more). The basic purpose of the subnet is to transmit message from one end to another end through intermediate nodes.
In most WAN a subnet consists of two types of elements:
Metropolitan Area Network (MAN)
A MAN, basically a bigger versions of a LAN is designed to extend over an entire city. It may be single network such as a cable television network, or it may be a means of connecting a number of LANs into a large network so that resources may be shared for example, a company can use a MAN to connect the LANs in all of its offices throughout a city.
A MAN typically covers an area of between 5 and 50 km diameter. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of buildings
The MAN, its communications links and equipment are generally owned by either a consortium of users or by a single network provider who sells the service to the users. This level of service provided to each user must therefore be negotiated with the MAN operator, and some performance guarantees are normally specified.
A MAN often acts as a high-speed network to allow sharing of regional resources (similar to a large LAN). It is also frequently used to provide a shared connection to other networks using a link to a WAN.
Wide Area Network (WAN)
The term Wide Area Network (WAN) usually refers to a network, which covers a large geographical area, and use communications subnets (circuits) to connect the intermediate nodes. A major factor impacting WAN design and performance is a requirement that they lease communication subsets from telephone companies or other communications carriers. Transmission rates are typically 2 Mbps, 34 Mbps, 155 Mbps, 625 Mbps (or sometimes considerably more). The basic purpose of the subnet is to transmit message from one end to another end through intermediate nodes.
In most WAN a subnet consists of two types of elements:
- Transmission lines.
- Switching element.
Transmission lines also called channels move about from one machine to another machine. The basic purpose of the switching element is to select the outgoing path for forwarding the message.
Numerous WANs have been constructed, including public switched networks, large corporate networks, military networks, banking networks, stock brokerage networks, and airline reservation networks. A WAN is wholly owned and used by a single company is often referred to as an enterprises network.
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