Week 12 (2012) Dr. Ghada Drahem

INTENDED LEARNING OUTCOMESThis lecture covers:

Networking concepts and terminology Common networking and communications applications Technical issues related to networks, including the major types

of networks, how data is transmitted over a network, and types of transmission media involved

Explanation of the various ways networked devices communicate with one another

Various types of hardware used in conjunction with a computer network

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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

Types of networksBusiness networksPhone networksHome and multimedia networks

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NETWORKING AND COMMUNICATIONS APPLICATIONS

Mobile phones (wireless phones)Cellular (cell) phones

Must be within range of cell tower to functionSatellite phones

Used where cell service isn’t availableDual-mode phones

Allows users to make telephone calls on more than one network

Cellular / Wi-Fi dual mode phone are most popular

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NETWORKING AND COMMUNICATIONS APPLICATIONS

PagingSending short

numeric or text messages to a person’s pager

Most often used for onsite paging applications

MessagingTwo-way pagingMost often takes

place today via a mobile phone

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NETWORKING AND COMMUNICATIONS APPLICATIONS

Global positioning system (GPS): Uses satellites and a receiver to determine the exact geographic location of the receiverCommonly found in cars todayAvailable as handheld unitsUsed by the military, hikers, travelers,

and others who need to know their precise location

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NETWORKING AND COMMUNICATIONS APPLICATIONS

Videoconferencing: Use of communications technology for real-time, face-to-face meetings between individuals located in different places

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TYPES OF NETWORKSTopology: How the devices in the network

(called nodes) are arranged

Star networks: All devices connect to a central device or hub)

Bus networks: All devices connect to a central cable

Ring networks: Devices connect to one another in a ring

Mesh networks: Multiple connections between devices

Some networks use a combination of topologies

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NETWORK TOPOLOGIES

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TYPES OF NETWORKSClient-server networks

Client: PC or other device on the network that requests and utilizes network resources

Server: Computer dedicated to processing client requests

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TYPES OF NETWORKSPeer-to-peer networks: All computers at the

same levelInternet peer-to-peer (P2P) computing:

Performed via the Internet

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TYPES OF NETWORKSLocal area network (LAN): Small

geographical area (office, campus, etc.)Wide area network (WAN): Large

geographical area (Internet)Metropolitan area network (MAN): Serves

a metropolitan areaPersonal area network

(PAN): Connects personal devices for one individual, such as his or her portable PC, mobile phone, and portable printer

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TYPES OF NETWORKSWireless sensor networks (WSNs): Contain

sensors (devices that respond to a stimulus and generate an electrical signal that can be measured or interpreted)

Intranet: Private network set up by an organization for use by its employees

Extranet: Intranet that is at least partially accessible to authorized outsiders

Virtual private network (VPN): Secure path over the Internet that provide authorized users a secure means of accessing a private network via the Internet

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DATA TRANSMISSION CHARACTERISTICSAnalog vs. digital (waves vs. discrete)Bandwidth: The amount of data

that can be sent at during a given period of timeMeasured in bits per second (bps)

Serial vs. parallel transmissionSerial = 1 bitParallel = at

least 1 byte ata time

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DATA TRANSMISSION CHARACTERISTICSTransmission timing

Synchronous transmission (at regular, specified intervals)

Asynchronous transmission (sent when ready)

Isochronous transmission (sent at the same time as other, related, data)

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DATA TRANSMISSION CHARACTERISTICSTransmission directions

Simplex transmission (one way only)Half-duplex transmission (one way at a time)Full-duplex transmission (both ways at the same

time)

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DATA TRANSMISSION CHARACTERISTICS

Type of connectionsCircuit-switched: Dedicated path over a

network is established and all data follows that path

Packet-switched: Messages are separated into small units called packets and travel along the network separately Used to send data over the Internet

Broadcast: Data is sent out to all other nodes on the network Primarily used with LANs

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TYPE OF CONNECTIONS

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DATA TRANSMISSION CHARACTERISTICS

Wired connections: The PC is physically cabled to the networkCommon in schools, business, and

government facilitiesWireless connections: Typically use radio

waves to send data through the airRapidly becoming more popular in homes

and businessesWireless hotspots are commonly available in

public locations

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WIRED NETWORK TRANSMISSION MEDIA

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WIRELESS NETWORK TRANSMISSION MEDIA

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CELLULAR RADIO TRANSMISSIONS

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MICROWAVE AND SATELLITE TRANSMISSIONS

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NETWORKING STANDARDS ANDCOMMUNICATIONS PROTOCOLS

Standards: A set of criteria or requirements considered to be the approved model for something

Networking standards: Address how networked computers communicate and connect

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

In networking, standards and protocols specify how:Devices physically connect to a networkData is packaged for transmissionReceiving devices acknowledge signalsErrors are handled

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ETHERNETcommunications protocol

Ethernet: Most widely used communications protocol for wired LANsTypically used a bus or star topology and

twisted-pair, coaxial, or fiber-optic cablesPower over Ethernet: Allows electrical power

to be sent along with data on an Ethernet networkMost often used by businesses

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TCP/IP AND WIRELESS APPLICATION PROTOCOL (WAP)

TCP/IP (Transmission Control Protocol/Internet Protocol): Used for transferring data over the Internet

Wireless Application Protocol (WAP):A standard for delivering Internet content to mobile devices