1. Chapter 5: Computer Networks

2. What Is a Network? *Network: A connected system of objects or people
*Computer network: A collection of computers and other hardware devices connected together so that users can share hardware, software, and data, as well as electronically communicate with each other
*Internet: Largest computer network in the world
*Examples of networks
-Business networks
-Phone networks

3. Networking and Communications Applications
1- Mobile phones (wireless phones)
*Cellular (cell) phones
- Must be within range of cell tower to function
*Satellite phones
- Used where cell service isn’t available

4. Networking and Communications Applications

5. Networking and Communications Applications
Global positioning system (GPS): Uses satellites to determine the exact geographic location of the receiver
-Commonly found in cars today
-Available as handheld units
-Used by the military, travelers, and others who need to know their precise location

6. Network Topologies
Topology: How the devices in the network (called nodes) are arranged
1-Star networks: All devices connect to a central device or hub)
2-Bus networks: All devices connect to a central cable
3-Ring networks: Devices connect to one another in a ring
4-Mesh networks: Multiple connections between devices
Some networks use a combination of topologies

7. Network Topologies

8. Types of Networks
1-Local area network (LAN): Small geographical area (office, campus, etc.) 2-Wide area network (WAN): Large geographical area (Internet) 3-Intranet: Private network set up by an organization for use by its employees 4-Extranet: Intranet that is at least partially accessible to authorized outsiders

9. Data Transmission Characteristics
*Transmission directions
-Simplex transmission (one way only)
-Half-duplex transmission (one way at a time)
-Full-duplex transmission (both ways at the same time)

10. Wireless Network Transmission Media
*Use radio signals
- Short-range (such as Bluetooth)
wireless keyboard
- Medium-range (such as Wi-Fi)
wireless LANs ,portable PC users to the Internet .
-Longer-range (Wi-MAX)
wide geographic areas

11. Communications Protocols
*Communications protocol: An agreed-upon standard for transmitting data between two devices on a network

12. TCP/IP and Wireless Application Protocol (WAP)
*TCP/IP (Transmission Control Protocol/Internet Protocol): Used for transferring data over the Internet
-Uses packet switching
*Wireless Application Protocol (WAP): A standard for delivering Internet content to mobile devices

13. Networking Hardware
1-Modem: Device that connects a computer to the Internet or to another computer

14. Networking Hardware for Connecting Devices and Networks
* Hub: Central device that connects all of the devices on the network
* Gateway: A devices that connects two different networks
- Bridge: Usually connects wired LANs
- Router : Can be wired or wireless

15. Other Networking Hardware
*Repeater: Amplifies signals along a network *Antenna: Used when Wi-Fi networks need to go further than hardware normally allows

16. Networking Hardware

17. Summary
*What Is a Network? *Networking and Communications Applications *Types of Networks *How Does Data Travel Over a Network? *Networking Standards and Communications Protocols *Networking Hardware