FR.AGNEL SCHOOL, NOIDACLASS VII NOTES

NETWORKING2018-2019

What is a Network?

A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.

Advantages of computer networkingThere are several distinct advantages to networking, including:

1. Ease of Access : The network stores most of the information on a central computer. Storing information on one central computer makes it easy for people to work with and manage their files.

2. Work from home : The network has dedicated computers that allow people to connect to the company’s network using a modem. Once user are connected to the network, they can work with any data available on the network

3. Share Resources : Computers connected to a network can share equipment’s and devices including printers and hard drives. The ability to share resources reduces the cost of buying computer hardware. For example instead of buying a printer for each person on a network, everyone on the network can share one central printer.

4. Share information : You can use a network to exchange information with other people. Information can be in any form of data, such as document created in a word processing program, or information provided by school database.

5. Security : Before accessing information on a network, user must enter a username and password. This ensures that only authorized people can use the information stored on the network

Network hardwareNetwork hardware includes the physical components that are used to create a network .All computer networks require at least the following hardware:

1. Computer2. Cables3. Connectors4. Network Interface Card(NIC)

Types of networksThere are several different types of computer networks. Computer networks can be characterized by their size as well as their purpose.The size of a network can be expressed by the geographic area they occupy and the number of computers that are part of the network. Networks can cover anything from a handful of devices within a single room to millions of devices spread across the entire globe.

Some of the different networks based on size are:

A   personal area network , or PAN, is a computer network organized around an individual person within a single building. This could be inside a small office or residence. A typical PAN would include one or more computers, telephones, peripheral devices, video game consoles and other personal entertainment devices.

Local Area Network

A local area network, or LAN, consists of a computer network at a single site, typically an individual office building, . A LAN is very useful for sharing resources, such as data storage and printers. LANs can be built with relatively inexpensive hardware, such as hubs, network adapters and Ethernet cables.

The smallest LAN may only use two computers, while larger LANs can accommodate thousands of computers.LANs are typically used for single sites where people need to share resources among themselves but not with the rest of the outside world. Think of an office building where everybody should be able to access files on a central server or be able to print a document to one or more central printers.

Metropolitan Area Network

A metropolitan area network, or MAN, consists of a computer network across an entire city, college campus or small region. A MAN is larger than a LAN, which is typically limited to a single building or site. Depending on the configuration, this type of network can cover an area from several miles to tens of miles. A MAN is often used to connect several LANs together to form a bigger network. When this type of network is specifically designed for a college campus, it is sometimes referred to as a campus area network, or CAN.

Wide Area Network

A wide area network, or WAN, occupies a very large area, such as an entire country or the entire world. A WAN can contain multiple smaller networks, such as LANs or MANs. The Internet is the best-known example of a public WAN.

Network Topology

Computers in a network have to be connected in some logical manner. The layout pattern of the interconnections between computers in a network is called network topology. You can think of topology as the virtual shape or structure of the network. Network topology is also referred to as 'network architecture.'

NodesDevices on the network are referred to as 'nodes.' The most common nodes are computers and peripheral devices. Network topology is illustrated by showing these nodes and their connections using cables. There are a number of different types of network topologies, including point-to-point, bus, star, ring etc.

Bus Topology

In this topology all the nodes are connected to a central cable called bus. In bus topology, a bus is a single continuous cable.

Transmission from any node travels the length of the bus in both directions and can be received by all other nodes. The bus has terminators at either ends which absorbs the signal, removing it from the bus.

Advantages

It is quite east to set up. Failure of one node does not affect the rest of the network.

Disadvantages:

It offers limited flexibility for change.  Difficult to identify the problem if the entire network shuts down.

Star Topology

In star topology, all the nodes are connected to a central system called switch, which forwards data towards its final destination. The switch controls the communication on the network.

Advantages

Star topology has minimal line cost. If any of the local computers fails the remaining portion of the network is unaffected.

Disadvantages:

The system crucially depends on the central switch. If central switch fails, the entire network goes down.

Ring Topology

The computers in this topology are connected in the shape of a closed ring. Data travels only in one direction in a ring, each computer passes the data to the next one on the line automatically.

Advantages

This type of network is easy to install and manage. If there's a problem in the network, it is easy to pinpoint which connection is defective. The transmission of data is relatively simple as data travel in one direction only. In ring topology all the traffic flows in only one direction at very high speed.

Disadvantages: If one workstation or port goes down, the entire network gets affected.

Network is highly dependent on the wire which connects different components. 

NETWORK ARCHITECTURE

Network architecture is an overall design of a computer network that describes how a computer network is configured and what strategies are being used. Computer network are of two main types.

CLIENT – SERVER NETWORK

It is a network where several computers called clients or workstations are connected to the main computer called the server.

A Server is a computer that provides services to clients and controls access to hardware, software and other resources.

Clients are the computers which request services like data retrieval, storage etc. from the server.

PEER-TO-PEER NETWORKPeer-to-Peer is a network where a few computers having equal capacity and capabilities are connected together to use the resources available on the network. In Peer-to-Peer network, there is no central server. Each computer can act as a server as well as client.