network basics chapter 9. network definition a network is a set of technologies that is used to...
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Network Basics
Chapter 9
Network DefinitionA network is a set of technologies that is used
to connect computersThe network allows communication and
collaboration between usersNetworking is a group of technologies working
together. These technologies include:1. Media is the wiring that connects the computers2. Hardware needs to be installed to connect the
media 3. Software needs to be written to handle
networks
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The Uses of a Network1. Simultaneous access to data
Network server is a central computer with large storage device and other resources that all users can share
Data files are sharedFile serversShared files stored on a server Access can be limited
Software can be sharedApplication servers Site licensesNetwork versions
Users can share data stored on Users can share data stored on central servercentral server
Network serverNetwork server
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The Uses of a Network2. Shared peripheral device
Printers and Faxes are commonly sharedReduces the cost per userDevices can be connected to the networkPrint servers control network printing
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The Uses of a Network3. Personal communication
– Email• Instantaneous communication
– Conferencing• Tele conferencing
1. Videoconferencing2. Audio-conferencing3. Data-conferencing
– Voice over IP• Phone communication
over network wires
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The Uses of a Network4. Easier data backup
Backup copies data to removable mediaServer data backed up in one step
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Assignment No. 2
a) What are the Network Operating Systems (NOS). Describe their roles?
b) Comparison of features of Linux and Windows operating systems
c) Write advantages and drawbacks of Internet in our life. (at least 5 each)
Due date: 05 February, 2009
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Common Network TypesLocal Area Network (LAN)
Contains printers, servers and computersSystems are close to each otherContained in one office or buildingOrganizations often have several LANS
Wide Area Networks (WAN)Two or more LANs connectedOver a large geographic areaTypically use public or leased lines
Phone linesSatellite
The Internet is a WAN
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Hybrid Network TypesMetropolitan Area Network (MAN)
Large network that connects different organizations
Shares regional resourcesA network provider sells timeTypically covers an area of between 5 and 50 km
diameter
Campus Area Networks (CAN)A LAN in one large geographic areaResources related to the same organizationEach department shares the LAN
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LAN, MAN, WAN
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Hybrid Network TypesHome Area Network (HAN)
Small scale networkConnects computers and entertainment
appliancesFound mainly in the home
Personal Area Network (PAN)Very small scale networkRange is less than 2 metersCell phones, PDAs, MP3 players
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How Networks Are StructuredServer based network
Node is any network deviceServers control what the node accessesUsers gain access by logging inServer is the most important computer
Client/Server networkNodes and servers share data rolesNodes are called clientsServers are used to control accessDatabase software
Access to data controlled by server
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How Networks Are StructuredPeer to peer networks (P2P)
All nodes are equalNodes access resources on other nodesEach node controls its own resourcesMost modern OS allow P2P NetworkDistributing computing is a form of P2PKazaa is a P2
Possible threats?
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Network TopologiesTopology
Logical layout of wires and equipmentChoice affects
Network performanceNetwork sizeNetwork collision detection
PacketsPieces of data transmitted over a network
• Packets are created by sending node• Data is reassembled by receiving node
Packet header• Sending and receiving address
Packet payload• Number and size of data• Actual data
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Network Topologies1. Bus topology
– Also called linear bus– One wire connects all nodes– Terminator ends the wires– Advantages
• Easy to setup• Small amount of wire
– Disadvantages• Slow• Easy to crash
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Network Topologies2. Star topology
– All nodes connect to a hub• Packets sent to hub• Hub sends packet to destination
– Advantages• Easy to setup• One cable can not crash network
– Disadvantages• One hub crashing downs entire network• Uses lots of cable
– Most common topology
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Network Topologies3. Ring topology
– Nodes connected in a circle– Tokens used to transmit data
• Nodes must wait for token to send
– Advantages• Time to send data is known• No data collisions
– Disadvantages• Slow• Lots of cable
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Network Topologies4. Mesh topology
All computers connected togetherInternet is a mesh networkAdvantage
Data will always be deliveredDisadvantages
Lots of cableHard to setup
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Network MediaLinks that connect nodes in a networkChoice can be made depending upon the
following factors:Speed of transmissionSize of networkSecurity
Can be broadly categorized as:Wire-Based MediaWireless Media
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Wire Based Media1. Twisted-pair
cablingMost common LAN
cableCalled Cat5 or
100BaseTFour pairs of copper
cable twistedMay be shielded
from interferenceSpeeds range from
1 Mbps to 1,000 Mbps
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Wire Based Media2. Coaxial cable
Similar to cable TV wireOne wire runs through cableShielded from interferenceSpeeds up to 10 MbpsNearly obsolete
3. Fiber-optic cableData is transmitted with light pulsesGlass strand instead of cableImmune to interferenceVery secureSpeeds up to 100 Gbps
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Wireless MediaData transmitted through the airLANs use radio wavesWANs use microwave signalsEasy to setupDifficult to secure
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Network HardwareNetwork interface cards
Network adapterConnects node to the mediaUnique Machine Access Code (MAC)
Network linking devicesConnect nodes in the networkCable runs from node to deviceCrossover cable connects two computers
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Network HardwareHubs
Center of a star networkAll nodes receive transmitted packetsSlow and insecure
SwitchesReplacement for hubsOnly intended node receives transmissionFast and secure
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Network HardwareBridge
Connects two or more LANs togetherPackets sent to remote LAN cross
Other packets do not crossSegments the network on MAC addresses
RouterConnects two or more LANs togetherPackets sent to remote LAN crossNetwork is segmented by IP addressConnect internal networks to the InternetNeed configured before installation
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Network HardwareGateway
Connects two dissimilar networksMost gateways contained in other devices
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Network CablingCabling specifications
Bandwidth measures cable speedTypically measured in Mbps
Maximum cable lengthConnector describes the type of plug
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Network CablingEthernet
Very popular cabling technology10 Base T, 10Base2, 10Base5Maximum bandwidth 10 MbpsMaximum distances100 to 500 meters
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Network CablingFast Ethernet
Newer version of EthernetBandwidth is 100 MbpsUses Cat5 or greater cable
Sometimes called 100Base TRequires a switch
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Network CablingGigabit Ethernet
High bandwidth version of Ethernet1 to 10 GbpsCat 5 or fiber optic cableVideo applications
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Network CablingToken ring
Uses shielded twisted pair cablingBandwidth between 10 and 25 MbpsUses a multiple access unit (MAU)Popular in manufacturing and finance
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Network ProtocolsLanguage of the network
Rules of communicationError resolutionDefines collision and collision recoverySize of packetNaming rules for computers
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Network ProtocolsTCP/IP
Transmission Control Protocol/Internet Protocol
Most popular protocolMachines assigned a name of 4 numbers
IP address209.8.166.179 is the White House’s web site
Dynamic Host Configuration ProtocolSimplifies assignment of IP addresses
Required for Internet access
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Network ProtocolsIPX/SPX
Internet Packet Exchange/Sequenced Packet Exchange
Older protocolAssociated with Novell NetwareReplaced by TCP/IP
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Network ProtocolsNetBEUI
Network BIOS Extended User InterfaceUsed by Windows to name computersTransmission details handled by TCP/IP
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Network ProtocolsToken ring
Popular in manufacturing and financeNodes communicate when they have the
token
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Modem CommunicationsPlain Old Telephone System (POTS)
Standard phone lineAlso known as Public Switched Telephone
Network (PSTN)Two-way voice communicationUses analog transmission techniquesData communication is slow
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Modem CommunicationsModems
Modulator/DemodulatorModulator converts digital to analog
Speed measured in bits per second (bps)Current fastest speed is 56 KbpsQuality of phone lines dictates speed
V.92 is the current modem standardSeveral modem types
InternalExternalVoiceFax
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Modem CommunicationsModem uses
Connection to the InternetFile transfer
UploadingDownloading
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Digital Data ConnectionsDigital phone lines
Local telephone companies are upgradingService will faster and more reliableNew phones will be neededModems will need to be upgraded
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Digital Data ConnectionsBroadband connection
Any data connection faster than 56 KbpsCommon in businessBecoming popular in home installations
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Digital Data ConnectionsISDN lines
Integrated Services Digital NetworkBasic rate uses three channels
Two data channels each support 64 KbpsError correction channel
Primary rate uses 24 data channels
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ISDN Connection
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Digital Data ConnectionsT lines
High-capacity voice/data linesUsed to control phone and dataSeveral variantsT1 transmits at 1.544 MbpsT3 transmits at 44.736 Mbps
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Digital Data ConnectionsDSL technologies
Digital Subscriber LinePopular with home usersSpeeds range from 100 Kbps to 30 MbpsAsymmetrical DSL (ADSL)
Upload speed slower than download speedSymmetrical DSL (SDSL)Requires a DSL modem
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Digital Data ConnectionsCable modem connections
Popular with home and office usersSpeeds between 1 and 3 MbpsRequires a cable modem
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Digital Data ConnectionsATM
Asynchronous Transfer ModeEfficient transfer of video and soundRequires a special NIC and hardware
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Wireless NetworksBenefits
No cable to pullMobile devices access network resourcesMobility and flexibility for office workers
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Wireless NetworksWireless 802.11
Also called Wi-FiIEEE standard
Institute of Electronic and Electrical EngineersSeveral versions
802.11b connects up to 11Mbps802.11g connects up to 56Mbps
Use the same type of devices
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Wireless NetworksWireless Access Point
Center of a wireless networkWAP combined cover a larger areaRange is 50 to 150 metersExtension points can extend range
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Wireless NetworksWireless Adapters
Used by devices to connectIncludes signal strength software
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ProjectAbstract Submission (next week)
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End of Chapter
Chapter 9