Networks

Although many individual computers users may have standalone machines (machines which are not connected to other computers), in institutional settings it is very common for two or more computers to be linked in a network. Networking allows two or more computer system of exchange information and share resources and peripherals.

There are several types of network. Some of the most common are:

1. LAN (Local Area Network): a network which covers a small physical area, for example, one building. LANs allows users to have common access to data and equipment such as printers, in addition to being able to communicate with each other using e-mail.

They can be built with two main types of architecture: peer-to-peer, where the two computers have the same capabilities, or client-server, where one computer acts as the server containing the main hard disk and controlling the order workstation or nodes, all the devices linked in the network (e.g. printers, computers, etc.).

Computers in LAN need to use the same protocol (standard of communication). Ethernet¹⁰is a very common cabling system that is used to connect computers.

Most network are linked with cables or wires but new WI-FI (Wireless Fidelity), technologies allow the creation of WLANs, where cables or wires are replaced by radio waves.

To build a WLAN you need access point, radio-based received-transmitters that are connected to the wired LAN, and wireless adapters installed in your computers to link it to the network.

Hotspots are WLANs available for public use in places like airports and hotels, but sometimes the service is also available outdoors (e.g. university campuses squares etc.).

2. WAN (Wide Area Network): a network which covers an even wider area, in which machines are usually connected via different ways. A WAN can be as small as two LANs which are connected, or as big as the Internet – the ultimate wide area network, covering the whole planet. They are usually linked through telephones lines, fibre-optic cables or satellites.

The main transmission paths within a WAN are high speed lines called backbones.

3. MAN (Metropolitan Area Network): a network which covers, for example, a city; may be used for university campuses.

4. Intranet: a network which uses the same technology as the Internet. The difference is that an intranet is private, and can only be accessed by a particular group of people, who have authorization (permission) to use it. An Intranet is often protected from unauthorized users with a firewall, a system which makes the intranet secure. Intranets are often used in business and education contexts. They may cover a geographically small area, or may be available to users over a large territory, and may even be global.

5. Extranet: a network which lies between an intranet and the Internet. It is like an intranet, in the sense that it is a private network, but it allows different degrees of access to different groups or individuals, using passwords. For example, a company may have an intranet which their own employees can access fully, but which their business partners and customers can only access partially. It’s very convenient in the case of cloud computing and VPN (Virtual Private Network).

5. Prepare a short summary of the text using the following expressions:

The main idea of the text is…

The problems/statements/points mentioned/discussed/described in the text are…

The text is divided into… logical parts…

The first/second/third logical parts deals with the problems/statement/points of/contains information about/ gives the definition of…

In my opinion/ to my mind the text is…

6. Read the information opposite and correct the following statements¹¹:

1. LANs link computers and other devices that are placed far apart.

2. In a client-server architecture, all the workstations have the same capabilities.

3. The world protocol refers to the shape of the network.

4. Routers are used to link two computers.

5. Access points don’t need to be connected to a wired LAN.

6. Wireless adapters are optional when you are using WLAN.

7. Hotspots can only be found inside a building.

8. The internet is an example of a LAN.

9. Wireless WANs use fiber and cable as linking devices.

7. Use the words in the box to complete the sentences:

LAN

nodes

hub

backbones

WLAN

peer-to-peer

server

1. All the PCs on a… are connected to one, which is a powerful PC with a large hard disk that can be shared by everyone.

2. The style of… networking permits each user to share resources such as printers.

3. The star is a topology for a computer network in which one computer occupies the central part and the remaining… are linked solely to it.

4. At present Wi-Fi systems transmit data at much more than 100 times the rate of a dialup modem, making it an ideal technology for linking computers to one another and to the Net in a….

5. All of the fibre-optic… of the United States, Canada and Latin America cross Panama.

6. A… joins multiple computers (or other network devices) together to form a single network segment, where all computers can communicate directly with each other.

8. Read these descriptions of different physical topologies of communication networks and name them:

1. All the devices are connected to a central station.

2. In this type of network there is a cable to which all the computers and peripherals are connected.

3. Two or more star networks connected together; the central computers are connected to a main bus.

4. All devices (computers, printers, etc.) are connected to one another forming a continuous loop.