Data Communication and Computer Networking Part # 1
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Overview of Data CommunicationOverview of Data Communicationand Computer Networksand Computer Networks
JUNAID QADAR JUNAID QADAR MSC ELECTRONICS (PREV) MSC ELECTRONICS (PREV)
Department of Electronics Department of Electronics University of PeshawarUniversity of Peshawar
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OutlineOutline Data Communication OverviewData Communication Overview
DefinitionDefinition ComponentsComponents Protocols and standardsProtocols and standards
Network OverviewNetwork Overview ConnectivityConnectivity CategoriesCategories InternetworksInternetworks
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Motivations Motivations Efficient way to share resourcesEfficient way to share resources
Cost Cost –– less expensive less expensive Accessibility Accessibility –– easier easier
Efficient way to exchange informationEfficient way to exchange information Time Time –– faster faster Size Size –– bigger bigger Correctness Correctness –– more accurate more accurate
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Data Communication: Data Communication: DefinitionDefinition
Data Communication:Data Communication:
Transfer of data from one device to another via some form of transmission medium.
Transfer of data from one device to another via some form of transmission medium.
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Data CommunicationData Communication
Hi, how are you?
01010001
Hi, how are you?
UserComputer
you?
how
are
Hi,
you?
how
are
Hi,
01010001
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Components in CommunicationComponents in Communication
Hi, how are you?
5 Protocol
4 Medium
3 Receiver2 Sender
1 Message
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Data RepresentationData Representation NumbersNumbers
8/16/32 bit integers8/16/32 bit integers floating pointfloating point
TextText ASCII, UnicodeASCII, Unicode
ImagesImages Bit patterns, Graphics formats JPG/GIF/etcBit patterns, Graphics formats JPG/GIF/etc
Audio Audio →→ Samples of continuous signal Samples of continuous signal Video Video →→ Sequence of bitmap images Sequence of bitmap images
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2
255
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Protocols and StandardsProtocols and Standards ProtocolProtocol
A set of rules governing data communicationsA set of rules governing data communications Syntax:Syntax: format of data block format of data block Semantics:Semantics: meaning of each section meaning of each section Timing:Timing: speed and sequencing speed and sequencing
StandardsStandards De factoDe facto (in practice) standards (in practice) standards
→→ not approved but widely adoptednot approved but widely adopted De jureDe jure (in law) standards (in law) standards
→→ approved by an organizationapproved by an organization
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Standards OrganizationsStandards Organizations Creation CommitteesCreation Committees
ISO, ITU-T, ANSI, IEEE, EIAISO, ITU-T, ANSI, IEEE, EIA ForumsForums Regulatory AgenciesRegulatory Agencies
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Direction of Data FlowDirection of Data Flow SimplexSimplex : One direction only: One direction only
Server Monitor
data flow
Keyboard
data flow
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Direction of Data FlowDirection of Data Flow Half Duplex:Half Duplex: Both directions, one at a time Both directions, one at a time
E.g., walkie-talkiesE.g., walkie-talkies
data flow at time 1
data flow at time 2
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Direction of Data FlowDirection of Data Flow Full DuplexFull Duplex : Both directions simultaneously: Both directions simultaneously
E.g., telephoneE.g., telephone
Can be emulated on a single communication link Can be emulated on a single communication link using various methodsusing various methods
data flow
data flow
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NetworksNetworks Network: Network: a set of devices connected by a set of devices connected by
media linksmedia links
Media Links
Printer
Workstation
Laptop
Scanner
Server
SD
iMac
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Types of ConnectionsTypes of Connections Point-to-pointPoint-to-point Multipoint (multidrop)Multipoint (multidrop)
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TopologyTopology Topology: physical or logical arrangement Topology: physical or logical arrangement
of devicesof devices MeshMesh StarStar BusBus RingRing HybridHybrid
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Fully Connected Mesh TopologyFully Connected Mesh Topology Pros:
Dedicated links Robustness Privacy Easy to identify fault
Cons: A lot of cabling I/O ports Difficult to move
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Star TopologyStar Topology Pros:
One I/O port per device
Little cabling Easy to install Robustness Easy to identify fault
Cons: Single point of failure More cabling still
required
Hub
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Bus TopologyBus Topology Pros:
Little cabling Easy to install
Cons: Difficult to modify Difficult to isolate fault Break in the bus cable
stops all transmission
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Ring TopologyRing Topology
Pros: Easy to install Easy to identify fault
Cons: Delay in large ring Break in the ring stops all
transmission
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Hybrid TopologiesHybrid Topologies
A C TA C T
1 0 M 1 0 0 M
1 2 3 4
1 3 1 4 1 5 1 6
5 6 7 8
1 7 1 8 1 9 2 0
9 1 0 1 1 1 2
2 1 2 2 2 3 2 4
U P L I N K
1 2 3 4 5 6 7 8 9 1 0 1 1 1 2
1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4
C O LC O L
P W R
S W I T C H
A C TA C T
1 0 M 1 0 0 M
1 2 3 4
1 3 1 4 1 5 1 6
5 6 7 8
1 7 1 8 1 9 2 0
9 1 0 1 1 1 2
2 1 2 2 2 3 2 4
U P L I N K
1 2 3 4 5 6 7 8 9 1 0 1 1 1 2
1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4
C O LC O L
P W R
S W I T C H
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Network CategoriesNetwork Categories Local Area Network (LAN)Local Area Network (LAN) Wide Area Network (WAN)Wide Area Network (WAN) Metropolitan Area Network (MAN)Metropolitan Area Network (MAN)
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Local Area NetworksLocal Area Networks Network in a single office, building, or Network in a single office, building, or
campuscampus
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Wide Area NetworksWide Area Networks Network providing long-distance communication Network providing long-distance communication
over a country, a continent, or the whole worldover a country, a continent, or the whole world
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Metropolitan Area NetworksMetropolitan Area Networks Network extended over an entire cityNetwork extended over an entire city
Bangkhen Kampangsaen
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Network of NetworksNetwork of Networks
Company A
Company D
Network Interface Card (NIC)
Company B
Company C
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InternetworkingInternetworking How to allow devices from different How to allow devices from different
standards to communicatestandards to communicate Gateways/routersGateways/routers – devices capable of – devices capable of
communicating in several standardscommunicating in several standards
These become "These become "network of networksnetwork of networks""
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InternetworksInternetworks Two or more networks connected become Two or more networks connected become
an an internetworkinternetwork, or , or internetinternet
Example: Example: The InternetThe Internet
Network1 Network2
Gateway
Network3
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The InternetThe Internet The largest internetwork (network of networks) in The largest internetwork (network of networks) in
the worldthe world Devices communicating with TCP/IP protocol Devices communicating with TCP/IP protocol
suitesuite
UCLA
Stanford
UC Santa Barbara
U. of Utah
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SummarySummary Data communicationData communication
Protocols and standardsProtocols and standards Computer networksComputer networks
TopologiesTopologies LAN/MAN/WANLAN/MAN/WAN
Internetworks (networks of networks)Internetworks (networks of networks)
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