I. Read the following words:

interconnected, classify, bridge, hub, switch, router, fiber, wireless, medium, internal, arrangement, architecture, coaxial, high-speed, employees, provide, topology, distinct, limited, layer, cover, performance, agreement, authentication, content, encryption, customer, metropolitan, layer, visual, typically.

II. Before you read the text try to answer these questions:

1. What is а computer network?

2. What types of computer networks do you know?

3. What is «Internet»?

III. Read and translate the following text. Computer networks

Computer network is a group of interconnected computers that can be classified according to wide varieties of characteristics. All networks are made up of basic blocks, such as Network Interface Cards (NICs), bridges, hubs, switches, routers and allow computers to communicate with each other, share resources and information. The first computer network, Advanced Research Projects Agency Network (ARPANET), was designed by the Advanced Research Projects Agency (ARPA) and appeared in 1970. The types of connection which are used to interconnect the individual devices in the network are as follows: Optical fiber, Ethernet, Wireless LAN and others.

Ethernet uses physical wiring to connect devices. ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/sec) local area network. Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium.

According to their scale, scope and purpose, networks are often classified as Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), Personal Area Network (PAN), Virtual Private Network (VPN), Campus Area Network (CAN), Storage Area Network (SAN). These types of networks are often differ in access levels and rights, e.g., LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations (such as, a building), while WANs may connect physically separate parts of an organization together and may include connections to the third parties.

The functional relationships (network architectures) exist between the elements of the network, e.g., Active Networking, Client-server and Peer-to-peer (workgroup) architecture.

Computer networks may be classified according to the network topology which the network is based upon, such as bus network, star network, ring network, mesh network, star-bus network, tree or hierarchical topology network. Network topology signifies the way in which devices on the network can see their logical relations. According to their scale computer networks are also divided into several types.

A personal area network (PAN) is a computer network used for communication among computer devices close to one person. Some examples of devices used in a PAN are printers, fax machines, telephones, PDAs and scanners. The area of a PAN is typically about 6-9 meters, but it is expected to be increased with technology improvements.

A local area network (LAN) is a computer network covering a small physical area, like a home, office or small group of buildings, e.g., a school or an airport. Current wired LANs are based on Ethernet technology, although new standards like ITU-T G.hn also provide a way of creating a wired LAN with existing home wires (coaxial cables and phone lines).

A campus area network (CAN) is a computer network made up of interconnected local area networks (LANs) within a limited geographical area. It can be considered as a form of a metropolitan area network, specific to academic purposes. In the case of a university campus area network, the network is likely to link a variety of campus buildings including academic departments and libraries. A campus area network is larger than a local area network but smaller than a wide area network. The main aim of a campus area network is to facilitate access to the Internet and university resources.

A metropolitan area network (MAN) connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the city. To create a metropolitan area network specialists use routers, switches and hubs.

A wide area network (WAN) is a data communications network that covers a relatively broad geographic area and uses routers and public communications links. The largest and well-known example of a WAN is the Internet. WAN technologies generally function at the three layers of the OSI model: the physical layer, the data link layer and the network layer.

A global area networks (GAN) specification is under development by several groups and there is no common definition of it. In general, however, a GAN is a model for supporting mobile communications across an arbitrary number of wireless LANs and satellite coverage areas.

Internetworking involves connecting two or more distinct computer networks or network segments via a common routing technology and is called an internetwork. All interconnections among or between public, private, commercial, industrial or governmental networks may also be defined as an internetwork.

IV. Answer the following questions:

1. When was the first computer network created?

2. What devices are the basic blocks of the network?

3. What devices are used to create a metropolitan area network?

4. What is internetworking?

5. How much space does a personal area network occupy?

6. What is ITU-T G.hn?

7. How can computer networks be classified?

8. What is the difference between LAN and WAN?

V. Decide whether the following statements are true or false. It they are false, correct them.

1. Network topology depends on the «physical» layout of the network.

2. The largest and well-known example of a WAN is the Internet.

3. The area of a PAN is typically about 69 meters.

4. Computer networks may be classified according to the network architectures.

5. ARPANET appeared in 1979.

VI. Find and correct mistakes in the following sentences:

1. A computer network is a collection of computers and devices that connect to each other.

2. According to their scale computer network are also divided into several types.

3. The area is expected to be increase with technology improvements.

4. The functional relationships exist between the element of the network.

5. A computer network are a group of interconnected computers.

VII. Using the information in the text, complete the following sentences:

a)functional relationships b)CAN c)network topology d)wide area network e)local area networks

1. A campus area network is a computer network made up of an interconnection of __________ within a limited geographical area.

2. __________ signifies the way in which devices on the network see their logical relations.

3. A __________ is larger than a local area network but smaller than a wide area network.

4. A __________ is a computer network that covers a broad area.

5. Computer networks may be classified according to the __________ .