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Transcript of 1 Networks and the Internet Unit E. 2 Objectives Introduce Networks Classify Networks Understand...
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Networks and the Networks and the InternetInternet
Unit EUnit E
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ObjectivesObjectives
Introduce NetworksIntroduce NetworksClassify NetworksClassify NetworksUnderstand Network TopologyUnderstand Network TopologyExplore Network Hardware Explore Network Hardware Explore Communications ChannelsExplore Communications ChannelsTransport DataTransport DataExplore LAN StandardsExplore LAN StandardsExplore WirelessExplore Wireless
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ObjectivesObjectives
Understand Internet connectionsUnderstand Internet connections
Introduce IP Addresses and Domain Introduce IP Addresses and Domain NamesNames
Connect to the Internet using Dial-upConnect to the Internet using Dial-up
Connect to the Internet using Connect to the Internet using BroadbandBroadband
Connect to the Internet using CableConnect to the Internet using Cable
Connect to the Internet without WiresConnect to the Internet without Wires
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Communications NetworkCommunications Network
The combination of hardware, The combination of hardware, software and connecting links that software and connecting links that transport datatransport data
Data is encoded, sent to its Data is encoded, sent to its destination then decodeddestination then decoded
Source Transmitter Receiver Destination
EncodedData
CommunicationsChannel
Signal
DecodedData
Noise
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Shared ResourcesShared Resources
Networks share hardware, Networks share hardware, software, and datasoftware, and data
Sharing reduces costsSharing reduces costs– Peripheral devices, site licensesPeripheral devices, site licenses
Provides access to InternetProvides access to Internet
Share dataShare data– Groupware, e-mail, IM, online Groupware, e-mail, IM, online
conferencingconferencing
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Shared Resources (cont.)Shared Resources (cont.)
Networks are vulnerableNetworks are vulnerable– Unauthorized accessUnauthorized access– Malicious codeMalicious code
• Viruses, Trojan horses, wormsViruses, Trojan horses, worms
Networks are becoming more Networks are becoming more standardizedstandardized
Most benefits outweigh risksMost benefits outweigh risks– Computers can be protectedComputers can be protected
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Network Classifications by Network Classifications by Geographic CoverageGeographic Coverage
PAN: PAN: Personal Area Network Personal Area Network (PDAs)(PDAs)WAN:WAN: Wide Area Network Wide Area Network (Internet is one)(Internet is one)MAN:MAN: Metropolitan Area Network Metropolitan Area Network (50 miles)(50 miles)LAN:LAN: Local Area Network (single Local Area Network (single building)building)
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Network Classifications by Network Classifications by Organizational StructureOrganizational Structure
Client/Server: Client/Server: – One or more computers configured as One or more computers configured as
servers and other computers configures servers and other computers configures as clientsas clients
– Server is central repository for dataServer is central repository for data
Peer-to-Peer (P2):Peer-to-Peer (P2): – Treats every computer as an equalTreats every computer as an equal– Workstations transfer data to each other Workstations transfer data to each other
without going through serverwithout going through server– File-sharing networksFile-sharing networks
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Network Classifications by Network Classifications by Organizational StructureOrganizational Structure
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Network Software LicensesNetwork Software Licenses
Single-userSingle-user
Multiple-userMultiple-user– Priced per userPriced per user
Concurrent-userConcurrent-user– Certain number of copies at a timeCertain number of copies at a time
SiteSite– Any and all computers at a locationAny and all computers at a location
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Network ClassificationsNetwork Classifications
CATEGORYCATEGORY DESCRIPTIONDESCRIPTION EXAMPLESEXAMPLESGeographical Geographical Area where network devices Area where network devices
are locatedare locatedPAN, LAN, WAN, PAN, LAN, WAN, MANMAN
OrganizationalOrganizational Hierarchy of devicesHierarchy of devices Client/Server, P2PClient/Server, P2P
PhysicalPhysical Layout and relationship Layout and relationship between devicesbetween devices
Star, bus, ring, mesh, Star, bus, ring, mesh, treetree
NetworkNetwork Technologies for cables and Technologies for cables and signals that carry datasignals that carry data
Twisted-pair, coaxial, Twisted-pair, coaxial, or fiber-optic cable; or fiber-optic cable; RF; microwaves; RF; microwaves; Infrared; power or Infrared; power or phone linephone line
BandwidthBandwidth Capacity of networkCapacity of network Broadband, Broadband, narrowbandnarrowband
Communications Communications protocolsprotocols
Standards for orderly & safe Standards for orderly & safe data transferdata transfer
TCP/IP, SPX/IPX, TCP/IP, SPX/IPX, NetBEUI/NetBIOS, NetBEUI/NetBIOS, AppleTalkAppleTalk
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Network TopologyNetwork Topology
Physical arrangement of devices, Physical arrangement of devices, cables, and wirescables, and wires5 common topologies named for 5 common topologies named for their shapestheir shapes– StarStar (central connection point) (central connection point)– RingRing (connects devices in a circle) (connects devices in a circle)– BusBus (common backbone) (common backbone)– MeshMesh (each device connected to others) (each device connected to others)– TreeTree (blend of star and bus) (blend of star and bus)
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Network TopologyNetwork Topology
Star Bus Ring
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Network Topology (cont.)Network Topology (cont.)
Each connection point on a Each connection point on a network is a Node:network is a Node:– ServerServer– WorkstationWorkstation– Network peripheralNetwork peripheral– Network deviceNetwork device
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Interconnecting NetworksInterconnecting Networks
Two similar networks can be Two similar networks can be connected by a bridgeconnected by a bridge– Transfers data without regard to formatTransfers data without regard to format
GatewayGateway– A device or software used to join dissimilar A device or software used to join dissimilar
networks by making data compatiblenetworks by making data compatible
RouterRouter– Electronic device that connects 2 or more Electronic device that connects 2 or more
networksnetworks
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Network Hardware OverviewNetwork Hardware Overview
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Network HardwareNetwork Hardware
Server (also called host computer)Server (also called host computer)– Distribute resources to network usersDistribute resources to network users– Contains network management software Contains network management software
and filesand files
Workstation (also called client)Workstation (also called client)– PC on a LANPC on a LAN– Client is software that lets it talk to serverClient is software that lets it talk to server
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Network HardwareNetwork Hardware
Network Interface Card (NIC) Network Interface Card (NIC) – Example: Ethernet cardExample: Ethernet card
Connection DevicesConnection Devices– Modem:Modem: converts PC digital signals converts PC digital signals– Hub:Hub: connects nodes on a LAN connects nodes on a LAN– Router:Router: decides best way to route data decides best way to route data
on networkon network– Gateway:Gateway: entrance to another network entrance to another network– Repeater:Repeater: amplifies and regenerates amplifies and regenerates
signalssignals
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Network AddressesNetwork Addresses
Physical address: Physical address: – Every node has oneEvery node has one– Built into circuitry of Built into circuitry of
network devicenetwork device
Logical address:Logical address:– Used if physical address Used if physical address
is incompatible with is incompatible with particular networkparticular network
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Wired Communication Wired Communication ChannelsChannels
Twisted-pair cables (phones) Twisted-pair cables (phones) – STP: shielded twisted pairSTP: shielded twisted pair– UTP: unshielded twisted pair for small UTP: unshielded twisted pair for small
networksnetworks
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Wired Communication Wired Communication ChannelsChannels
Coaxial cable (television)Coaxial cable (television)– High capacityHigh capacity
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Wired Communication Wired Communication ChannelsChannels
Fiber-optic cable Fiber-optic cable – Pulses of light in thin glass tubesPulses of light in thin glass tubes– Essential to Internet backboneEssential to Internet backbone
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Wireless Communication Wireless Communication ChannelsChannels
RF: radio frequency signalsRF: radio frequency signals– Send and receive by a transceiver with Send and receive by a transceiver with
antennaantenna
MicrowavesMicrowaves– More capacity than radio wavesMore capacity than radio waves– Need clear path between transmitter Need clear path between transmitter
and receiverand receiver– Cannot penetrate metal objectsCannot penetrate metal objects
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Wireless Communication Wireless Communication ChannelsChannels
SatellitesSatellites– Signal relayed from ground station Signal relayed from ground station
to satelliteto satellite– Transponder on satellite receives, Transponder on satellite receives,
amplifies and retransmits signal amplifies and retransmits signal back to earthback to earth
– Key technology for Internet Key technology for Internet backbonebackbone
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Wireless Communication Wireless Communication ChannelsChannels
Infrared lightInfrared light– Short distance with clear line of siteShort distance with clear line of site– Example: connect notebook with printerExample: connect notebook with printer
Laser lightLaser light– Larger distance with clear line of siteLarger distance with clear line of site– Example: between buildings in futureExample: between buildings in future
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BandwidthsBandwidths
The transmission capacity of a The transmission capacity of a communications channel measured communications channel measured in bps (bits per second)in bps (bits per second)Low-bandwidth carries less data than Low-bandwidth carries less data than high bandwidthhigh bandwidth– TelephoneTelephone– NarrowbandNarrowband
High-bandwidthHigh-bandwidth– Coaxial cableCoaxial cable– DSL linesDSL lines– Called broadbandCalled broadband
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Transporting Data Transporting Data Depends On:Depends On:
Network Topology:Network Topology: configurationconfiguration
Packet Switching Packet Switching Technology:Technology: determines how determines how data is broken updata is broken up
Protocols:Protocols: rules for rules for successful and accurate successful and accurate data transmissiondata transmission
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Packet Switching TechnologyPacket Switching Technology
Packet is a parcel of data on network Packet is a parcel of data on network or a file broken into small, equal size or a file broken into small, equal size piecespiecesContainsContains– Sender addressSender address– Destination addressDestination address– Sequence numberSequence number– DataData
Packet switching: packets sent Packet switching: packets sent independently of each otherindependently of each other
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Circuit SwitchingCircuit Switching
Establishes a dedicated, private Establishes a dedicated, private link between phone lines during link between phone lines during a calla call
Inefficient because it reserves a Inefficient because it reserves a circuit even if data is not being circuit even if data is not being transmittedtransmitted
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Communications ProtocolCommunications Protocol
Allows two devices to negotiate Allows two devices to negotiate and agree on how data will be and agree on how data will be transmittedtransmitted
TCP/IP TCP/IP – Transport Control Protocol/Internet Transport Control Protocol/Internet
ProtocolProtocol– Most commonMost common– TCP: breaks data into packetsTCP: breaks data into packets– IP: addresses packetsIP: addresses packets
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Controlling Direction Controlling Direction of Data Flowof Data Flow
Simplex:Simplex: one direction (TV) one direction (TV)
Half duplex:Half duplex: can send and can send and receive data, but not at same receive data, but not at same time (CB radio)time (CB radio)
Full Duplex:Full Duplex: can send and can send and receive data at same time on receive data at same time on same channel (Telephone)same channel (Telephone)
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Protocol CharacteristicsProtocol Characteristics
Handshaking:Handshaking: negotiating negotiating transmission speedtransmission speed
Synchronous Protocol:Synchronous Protocol: sender and sender and receiver synchronize signal with a receiver synchronize signal with a fixed clock ratefixed clock rate
Asynchronous Protocol:Asynchronous Protocol: requires a requires a start and stop bit (most common)start and stop bit (most common)
Parity bits:Parity bits: used for error checking used for error checking
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Communications ProtocolsCommunications Protocols
PROTOCOLPROTOCOL MAIN USEMAIN USE
TCP/IPTCP/IP InternetInternet
NetBIOS/NETBEUINetBIOS/NETBEUI Microsoft Microsoft networksnetworks
AppleTalkAppleTalk Macintosh Macintosh networksnetworks
IPX/SPXIPX/SPX Novell networksNovell networks
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LAN StandardsLAN Standards
Institute of Electrical and Institute of Electrical and Electronics Engineers (IEEE)Electronics Engineers (IEEE)IEEE designation numbers IEEE designation numbers identify compatible network identify compatible network technologiestechnologies– ARCnet: old, simple, inexpensiveARCnet: old, simple, inexpensive– Token Ring: ring topologyToken Ring: ring topology– FDDI: fiber-optic cablesFDDI: fiber-optic cables– Ethernet: simultaneous broadcast of Ethernet: simultaneous broadcast of
data packetsdata packets
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EthernetEthernet
Packets accepted only by device Packets accepted only by device to which it is addressedto which it is addressedCSMA/CD protocolCSMA/CD protocolRefers to a family of LAN Refers to a family of LAN technologiestechnologies– Various transmission ratesVarious transmission rates– Fiber-optic and twisted-pair cablesFiber-optic and twisted-pair cables– Bus or star topologyBus or star topology
Connect many workstationsConnect many workstations
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EthernetEthernet
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Home Ethernet EquipmentHome Ethernet Equipment
Ethernet card in each Ethernet card in each workstation and peripheral workstation and peripheral devicedevice
Link between network nodes Link between network nodes such as cablesuch as cable
Central connection point (hub)Central connection point (hub)
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Wireless StandardsWireless Standards
Wi-Fi (Wireless Fidelity)Wi-Fi (Wireless Fidelity)– Set of wireless networking technologiesSet of wireless networking technologies– Defined by IEEE 802.11 standardsDefined by IEEE 802.11 standards– Compatible with EthernetCompatible with Ethernet
Popular because of absence of Popular because of absence of cablescables
Desirable for notebook and tablet Desirable for notebook and tablet computerscomputers
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Wi-Fi DisadvantagesWi-Fi Disadvantages
Speed Speed – Radio wavesRadio waves
DistanceDistance– 25-150 feet25-150 feet
SecuritySecurity– War driving/LAN-jackingWar driving/LAN-jacking– Wired Equivalent Privacy: encryptionWired Equivalent Privacy: encryption
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Wi-Fi (cont.)Wi-Fi (cont.)
Wi-Fi cards requiredWi-Fi cards required– Include transceiver and antennaInclude transceiver and antenna– Can be added to notebooks, PCs, and TabletsCan be added to notebooks, PCs, and Tablets– Wireless access point is same as hub or router Wireless access point is same as hub or router
in Ethernetin Ethernet
Bluetooth makes short-range Bluetooth makes short-range wireless connections between wireless connections between devices such as a mouse, keyboard, devices such as a mouse, keyboard, printer printer
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Internet ConnectionsInternet Connections
The Internet isn’t owned or The Internet isn’t owned or operated by corporations or operated by corporations or governmentsgovernments
Traffic exceeds 100 trillion bytes Traffic exceeds 100 trillion bytes (terabytes) each week(terabytes) each week
Backbone provides high-speed Backbone provides high-speed routes for data trafficroutes for data traffic
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Internet ConnectionsInternet Connections
Users connect to Internet Service Users connect to Internet Service Provider (ISP) or through LANProvider (ISP) or through LAN
ISP provides e-mail and access ISP provides e-mail and access to Webto Web
Networks use TCP/IP as Networks use TCP/IP as standard standard
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Internet ConnectionsInternet Connections
Ping software: Packet Internet GroperPing software: Packet Internet Groper– Checks internet pathways to be sure they are Checks internet pathways to be sure they are
openopen
Traceroute software: traces data pathsTraceroute software: traces data paths
HTTPHTTPHTTPHTTP
FTPFTPFTPFTP
POPPOPPOPPOP
SMTPSMTPSMTPSMTP
IMAPIMAPIMAPIMAPTELNETTELNETTELNETTELNET
SSLSSLSSLSSL
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IP AddressesIP Addresses
ISP gives unique IP address to ISP gives unique IP address to subscribersubscriberSeries of numbers in 4 partsSeries of numbers in 4 parts– 204.127.129.001204.127.129.001
Static IP address: permanent, usually Static IP address: permanent, usually serversserversDynamic IP address: temporary, for Dynamic IP address: temporary, for one sessionone sessionLook at your Internet configuration Look at your Internet configuration settings to find your IP addresssettings to find your IP address
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Domain NamesDomain Names
Translates directly into IP addressTranslates directly into IP address
Examples: course.com, rutgers.eduExamples: course.com, rutgers.edu
Top-level domain: indicated by Top-level domain: indicated by extensionextension
ICANN handles domain name ICANN handles domain name registration and controlregistration and control
infoinfoinfoinfo
netnetnetnet
eduedueduedu
comcomcomcom intintintintgovgovgovgov
milmilmilmil orgorgorgorg
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Dial-up Internet ConnectionsDial-up Internet Connections
Plain old telephone Plain old telephone service (POTS)service (POTS)Dial-up connection Dial-up connection via modemvia modemCircuit switching Circuit switching technology gives technology gives continuous private continuous private linklink
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Dial-up Internet ConnectionsDial-up Internet Connections
Modem: Modulate/demodulate; Modem: Modulate/demodulate; digital to analogdigital to analog– Speed: 56 KbpsSpeed: 56 Kbps– Upstream actually 33 KbpsUpstream actually 33 Kbps– Downstream actually 44 KbpsDownstream actually 44 Kbps
VIOP (Voice Over IP): can talk VIOP (Voice Over IP): can talk on computer at same time as on computer at same time as running other programs on-linerunning other programs on-line
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Broadband Internet Broadband Internet ConnectionsConnections
High-speed digital High-speed digital communications links for voice communications links for voice and dataand dataDSL: Digital Subscriber Line DSL: Digital Subscriber Line (always-on)(always-on)– Uses standard copper phone cablesUses standard copper phone cables– Fastest and most affordable to Fastest and most affordable to
individualsindividuals– Variations are ADSL, SDSL, HDSL Variations are ADSL, SDSL, HDSL
AND DSL liteAND DSL lite– DSL modems give 1.5 Mbps DSL modems give 1.5 Mbps
downstreamdownstream
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Broadband Internet Broadband Internet ConnectionsConnections
ISDN: Integrated Services Digital ISDN: Integrated Services Digital NetworkNetwork– 64 or 128 Kbps64 or 128 Kbps– Mostly used for business LANsMostly used for business LANs– Need ISDN terminal adapterNeed ISDN terminal adapter
–1.544 Mbps1.544 Mbps
–24 channels24 channels
–Used by business Used by business and ISPs on and ISPs on dedicated leased dedicated leased lineslines
T1T1–43 Mbps43 Mbps
–672 channels672 channels
–Also called DS3 Also called DS3 (Digital Service-3)(Digital Service-3)
T3T3
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Security When Always-OnSecurity When Always-On
Same IP address when Same IP address when on – hackers can useon – hackers can use
High-speed access High-speed access desirable for hackersdesirable for hackers
Turn machine off oftenTurn machine off often
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Cable Internet ConnectionsCable Internet Connections
You need You need – Ethernet card Ethernet card – Cable modem: usual ISP Cable modem: usual ISP
providesprovides– Splitter to connect both Splitter to connect both
modem and TB if necessarymodem and TB if necessary
Could slow down as Could slow down as more neighbors use more neighbors use serviceservice
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Cable SecurityCable Security
DOCSIS-compliant cable DOCSIS-compliant cable modemsmodems– Security technology filters packets to Security technology filters packets to
certain portscertain ports– Secures your computer from your Secures your computer from your
neighborsneighbors– Doesn’t close up all security holes Doesn’t close up all security holes
associated with always-on connectionsassociated with always-on connections
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Wireless Internet ConnectionsWireless Internet Connections
DSS: Direct Satellite ServiceDSS: Direct Satellite Service– Some allow only downstreamingSome allow only downstreaming
Two-way Satellite ServiceTwo-way Satellite Service– Downstream 500 Kbps vs. 40-60 Kbps Downstream 500 Kbps vs. 40-60 Kbps
upstreamupstream
Cellular telephone infrastructure Cellular telephone infrastructure is slowest at 14.4 Kbpsis slowest at 14.4 Kbps
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Wireless Internet ConnectionsWireless Internet Connections
Mobile Internet ConnectionsMobile Internet Connections
Public Wi-FiPublic Wi-Fi– Range of coverage: hotspotRange of coverage: hotspot
WWAN (wireless WAN)WWAN (wireless WAN)– Cell phone networksCell phone networks– Cell-ready modem or subscriptionCell-ready modem or subscription
WAP (wireless access protocol)WAP (wireless access protocol)
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TechTalk: Installing a LANTechTalk: Installing a LAN
Install Ethernet NICInstall Ethernet NIC– On motherboard or with PC card; both have On motherboard or with PC card; both have
port for network cableport for network cable
Attach cable to NIC port and hub portAttach cable to NIC port and hub portTurn on PCsTurn on PCsWindows should automatically detect Windows should automatically detect and establish connectionand establish connectionCan activate file sharing and drive Can activate file sharing and drive mapping by using Windows Network mapping by using Windows Network NeighborhoodNeighborhood
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Context: EducationContext: Education
CBT (computer-based training)CBT (computer-based training)CAL (computer-aided learning)CAL (computer-aided learning)CAI (computer-aided instruction)CAI (computer-aided instruction)SimulationsSimulations99% of American public schools 99% of American public schools have computershave computers– Not all students have daily access Not all students have daily access
thoughthough
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Context: EducationContext: Education
Some colleges require incoming Some colleges require incoming students to have a computerstudents to have a computer
DE/DL (Distance DE/DL (Distance Education/Learning)Education/Learning)
Life-long learningLife-long learning
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Issue: Free Wi-Fi?Issue: Free Wi-Fi?
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Networks and the Networks and the InternetInternet
EndEnd