chapter 1 9thfeb

Department of Electrical Engineering.COMSATS Institute of Information Technology, Islamabad.Department of Electrical Engineering.COMSATS Institute of Information Technology, Islamabad.

EEE314:DATA COMMUNICATIONS & COMPUTER NETWORKS& COMPUTER NETWORKS

ATIF SHAKEEL(MSc NETWORKS & DISTRIBUTED SYSTEMS, SWEDEN)

1EEE 314: Data Communications &

Computer Networks.

Department of Electrical Engineering.COMSATS Institute of Information Technology, Islamabad.

COURSE HOME PAGE : http://groups.yahoo.com/group/DCCN‐Fall2011‐CIIT/

COURSE EMAIL: DCCN‐Fall2011‐[email protected]

INSTRUCTOR EMAIL:[email protected]

EEE 314: Data Communications & Computer Networks.


Computer Networks.

NETWORK SUPPORTING THE WAY WE LIVE



Computer Networks.3



Computer Networks.4

INTRODUCTIONINTRODUCTION

• What is Communication?What is Communication?

• What is Data Communication?

i i i h h f dData communications is the exchange of databetween two devices via some form of

i i ditransmission medium.

Data refers to information presented inwhatever form that is agreed upon by theparties creating and using the data.



Computer Networks.5

FUNDAMENTAL CHARACTERISTICSFUNDAMENTAL CHARACTERISTICS

• Effectiveness of Data communicationsEffectiveness of Data communicationsdepends on following characteristics.– Delivery– Delivery

– Accuracy

Timeliness– Timeliness

– Jitter


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COMPONENTS OF DATA COMMUNICATIONSCOMMUNICATIONS

• Message

• Sender• Sender

• Receiver

T i i di• Transmission medium

• Protocol


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DATA REPRESENTATIONDATA REPRESENTATION

• Information can be sent in different formsInformation can be sent in different forms– Text

Numbers– Numbers

– Images

A di– Audio

– Video


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DATA FLOWDATA FLOW


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DATA FLOWDATA FLOW

• Communication between two devices can be:Communication between two devices can be: – Simplex

Half Duplex– Half‐Duplex

– Full‐Duplex


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NETWORKSNETWORKS

•• AA networknetwork isis aa setset ofof devicesdevices (often(often referredreferred toto asasAA networknetwork isis aa setset ofof devicesdevices (often(often referredreferred toto asasnodes)nodes) connectedconnected byby communicationcommunication linkslinks.. AA nodenodecancan bebe aa computer,computer, printer,printer, oror anyany otherother devicedevicecapablecapable ofof sendingsending and/orand/or receivingreceiving datadata generatedgeneratedbyby otherother nodesnodes onon thethe networknetwork..AA I t t dI t t d tt ff thithi ll•• AnAn InterconnectedInterconnected systemsystem ofof thingsthings oror peoplepeople..


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• Distributed Processing– Most Networks uses distributed processing, inwhich task is divided among multiple computers.

• Network Criteria– A network must be able to meet certain numberof criteria, the most important are:

• Performance

R li bili• Reliability

• Security


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TYPES OF PHYSICAL CONNECTION• Point‐to‐Point Connection

• Multipoint ConnectionMultipoint Connection


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PHYSICAL TOPOLOGYPHYSICAL TOPOLOGY

• Way in which network is laid out physicallyWay in which network is laid out physically.Two or more devices connect to a link; two ormore links from a topologymore links from a topology.


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MESH TOPOLOGY– Every device has a dedicated point to point link to every other device.

– A fully connected mesh network has n(n‐1)/2 physical channels to linkn devicen device.

– Every device must have n‐1 I/O ports.

– Advantages:

– Eliminating traffic problems due to dedicated links.

– Robust.

– Privacy or security.

– Easy for fault identification and isolation.

– Disadvantages:

– High cost due to amount of cabling and the network I/O portsHigh cost due to amount of cabling and the network I/O portsrequired.

– Difficult and complex installment.


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FULLY CONNECTED MESH TOPOLOGY ( )(FIVE DEVICES)


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STAR TOPOLOGYSTAR TOPOLOGY

• Each device has a dedicated point‐to‐point link only to a central controller,usually called hub.

• Does not allow direct traffic between devices, the controller acts as anexchange.

• Advantages:

• Less expensive then mesh topology.

• Easy to install and reconfigureEasy to install and reconfigure.

• Robust

• Easy fault identification and fault isolation.

Di d• Disadvantages:

• Could be costly due to Hub but still highly recommended due to itsadvantages over other topologies.


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Star Topology with four stationsStar Topology with four stations


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BUS TOPOLOGY• One long cable acts as a backbone (Bus) to link all other

devices (nodes) in a network. Nodes are connected to the buscable by drop lines and tapscable by drop lines and taps.

• Mesh, Star are point to point. Bus is multipoint.• Propagating signal through the bus starts fading due to loss of

energy as heat. Thus there is a limit on the number of tapsand the distance between those taps.

• Advantages:g– Ease of installation.

• Disadvantages:Difficult reconnection– Difficult reconnection.

– Difficult fault isolation.– A fault or break in the bus cable stops all transmission to the further

segment


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segment.

Bus Topology Connecting three stations.


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RING TOPOLOGY• Each device has a dedicated point‐to‐pointconnection only with the two devices on either sideof it A signal is passed along the ring in oneof it. A signal is passed along the ring in onedirection, from device to device, until it reaches itsdestination.E h d i i h i i• Each device in the ring incorporates a repeater.

• Advantages:– Easy to install and reconfigure with considerations likeEasy to install and reconfigure with considerations likemaximum ring length and number of devices.

– Simplified fault isolation.• Disadvantage:• Disadvantage:

– Due to unidirectional traffic, a break in the ring can disablethe entire network.


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Ring Topology connecting six stations.Ring Topology connecting six stations.


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HYBRID TOPOLGYHYBRID TOPOLGY


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CATEGORIES OF NETWORK

Network

Metropolitan Wide areaLocal area Metropolitan area network

(MAN)

Wide area network (WAN)

Local area network (LAN)


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LOCAL AREA NETWORK– Usually privately owned and links the devices in asingle office, building or campus.g , g p

– Geographical size is few kilometers.– Designed to allow resources (hardware, softwareg (or data) to be shared between personalcomputers or work stations.I l t f di– In general use one type of media.

– Topologies: bus, ring and star.Data rates: 4 to 16 Mbps Recent advancements– Data rates: 4 to 16 Mbps. Recent advancementssupport up to 100 Mbps and Gbps is indevelopment.


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p

LAN connecting 12 computers in a HubLAN connecting 12 computers in a Hub


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METROPOLITAN AREA NETWORKMETROPOLITAN AREA NETWORK– Designed for the customers who need a high

d i i ll h i dspeed connectivity, normally to the internet andspread over a city or part of city.

M b i l t k b f– Maybe a single network or maybe a means ofconnecting number of LANs into a larger networkso that resources may be shared LAN‐to‐LAN asso that resources may be shared LAN to LAN aswell as device‐to‐device.

– Example: A company can use a MAN to connectExample: A company can use a MAN to connectLANs in all its offices throughout a city.


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Metropolitan Area NetworkMetropolitan Area Network


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WIDE AREA NETWORK– Provides long distance transmission of data, voice, image and video

information over large geographic areas that may comprise a country,a continent or even the whole worlda continent, or even the whole world.

– Switched WAN:• connects the end systems, which usually comprise a router(internetworking connecting device) that connects to another LANor WAN

• complex as the backbones that connect the Internet.

– Point‐to‐Point WAN:• A line leased from a telephone or cable TV provider that connectsa home computer or a small LAN to an Internet service providera home computer or a small LAN to an Internet service provider(lSP).

• simple as a dial‐up line that connects a home computer to theInternet


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Internet

A Switched WAN & Point‐to‐Point WAN


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A Heterogeneous Network made of 4 WANs and 2 LANsWANs and 2 LANs


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INTERNETINTERNET


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Hierarchical Organization of Internet


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PROTOCOLS

• PROTOCOLA l i f l h d– A protocol is a set of rules that govern datacommunications; the key Elements of a protocolare syntax semantics and timingare syntax, semantics and timing.

• Syntax– Structure or format of the data.

• Semantics– Meaning of each section of bits.

Ti i• Timing– When data should be sent, and how fast data can be sent.


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STANDARDSSTANDARDS

• Standard are necessary to ensure thatStandard are necessary to ensure thatproducts from different manufacturers canwork together as expectedwork together as expected.

• Data Communication Standards fall in to twocategoriescategories.– De facto

D j– De jure


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STANDARD ORGANIZATIONSSTANDARD ORGANIZATIONS

• International Organization for StandardizationInternational Organization for Standardization (ISO)

• International Telecommunication Union• International Telecommunication Union‐Telecommunication Standards Sector (ITU‐T)

A i N i l S d d I i (ANSI)• American National Standards Institute (ANSI)

• Institute of Electrical and Electronics Engineers(IEEE)

• Electronics Industries Association (EIA)


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( )

To‐Do ListTo Do List

• At least go through all the slides once in orderAt least go through all the slides once in order to grasp the concept before the next lecture.

• Join the Group Home page as soon asJoin the Group Home page as soon as possible.

• Lecture Slides for the next lecture will beLecture Slides for the next lecture will beuploaded on the group home page before thelecture.

• Any concern regarding the course, email onthe DCCN‐Fall2011‐[email protected]


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THANK YOU FOR YOURTHANK YOU FOR YOUR

ATTENTION.


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chapter 1 9thfeb

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