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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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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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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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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