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 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

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 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

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