Chapter 5: Computer Networks

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

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

Networking and Communications Applications

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

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 cable3-Ring networks: Devices connect to one another in a

ring4-Mesh networks: Multiple connections between

devicesSome networks use a combination of topologies

Network Topologies

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

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)

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

Communications Protocols

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

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

Networking Hardware

1-Modem: Device that connects a computer to the Internet or to another computer

Networking Hardware for ConnectingDevices 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

Other Networking Hardware

*Repeater: Amplifies signals along a network*Antenna: Used when Wi-Fi networks need to

go further than hardware normally allows

Networking Hardware

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