Types of Networks and Network Devices - A Comprehensive Guide

1. Chapter 3 Data Transfer and Networks

2. Network Is a group of computers connected to each other to share resources , such as printers and peripheral equipment, and to share files and programs .

3. Types of Networks • Local Area Network (LAN) • A network within a limited area • Wireless Local Area Network(WLAN) • Links computers using wireless technologies, like radio waves • Wide Area Network (WAN) • A network in large areas. Mostly use satellites. • Example ATM of banks networks

4. Network Devices(used in large networks)-1 • Multiplexers • Combine data and transmits it on high speed links. 2 are used at each end • Front-end Processor • small-sized computer that does all communications for host computer. • Bridge • Connects 2 similar (نفس النوع) LAN’s to send and receive messages

5. Network Devices(used in large networks)-2 • Gateway • Same as bridges, but connects different LAN’s • Router • Directs messages by choosing optimum (المثالي) path. • Repeaters • Used to repeat or amplify network signals in long distances.

6. Network Devices Multiplexer Front end processor Router (wireless) Bridge Repeater Gateway

7. Client /Server Networks • In there is a specific computer called a server , which serves all common files and documents so that other computers (Clients) can use , access , update and manipulate them at the same time. • Kinds of Servers : • File Servers • High speed, big capacity. • Printer Servers • Communication Servers . • Connect NT computer with outside computers • Dedicated Servers • Like web server, e-mail server.

8. Some Concepts • Internet • The largest network. Connects computers around the world. • Intranet • Private network. Used to share company’s information and resources. • Extranet • An intranet that allows people fro outside the company to access information. Privileges (صلاحيات) are controlled via “Firewalls” • World Wide Web • Collection of web pages linked via hyperlinks. It’s a part of the internet.

9. Data Transfer • Downloading: copying files from the network to your computer. • Uploading: copying files from your computer to the network • Transfer Rate: volume of data transmitted per second. Measured by: bps, Kbps, Mbps. • Digital and Analogue Signals • Modem: converts analogue signals (telephone)into digital (computer) and vice versa. Speed measured in baud (bits per second).

10. Data Transmission Media • Wired Media • 1. Twisted Pairs : 4 pairs of twisted • wires . Like telephone wires 2. Coaxial Cable : single wire, wrapped • in a mesh of thin wires. Like video cables 3. Fiber Optic Cables: very thin glass or plastic threads. Very fast transfer. • Wireless Media

11. Network Interface Card Is a circuit that is plugged in expansion slots so the computer can be connected to other computers . It transmits data and executes protocols.

12. Internet Connection • Dial-Up Connection : use a telephone line and a modem inside your computer’s system box. Very slow, telephone is busy while you’re connected. • Broadband Connection: high speed connection, available 24 hours a day, free telephone line. Fees are paid monthly

13. Options For Internet Connection • Phone Line • Requires a phone line, a modem and an ISP account. • Mobile Phone • Wireless technology, speed can be up to 1Mbps depending on provider • Satellite • Very high speed connection, but requires special equipments  expensive • Wireless Hotspot • Use of radio waves (wireless) usually free, but don’t allow downloading.

14. Characteristics of Broadband • Fast Connection to the Internet • An always on connection • Fast Fee Payment • Risk of intruder attack