networking kgc

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November 29, 2012 1

Concepts of Networking


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November 29, 2012 2

Table of Content

Concept of networking

Advantages of networking

LAN, MAN , WAN

Concept of Internet , Intranet and extranet

Hardware Requirements for Network

Modems, Multiplexers, Switches, Routers etc.Cables - Coaxial, Fiber Optic and others

Topology

Concept and Advantages and disadvantages of

Star, Ring, Bus, Tree and Mesh.

Protocols

Concepts and types of Protocols

ISO Model

Internet Protocol

Operating Systems


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November 29, 2012 3

Concept of Networking

In its simplest form, a network is at least two computers

desktops, laptops or one of each

connected together with wireless or wired technologies.

That's it.

For example, let's say you've got a desktop and a laptop in your home or office.

Here are your computers:

What is Network ??


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Before Network

After Network

Concept of Networking


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WHY A COMPUTER NETWORK ?

Distribute computation among nodes

Coordination between processes running on

different nodes

Remote I/O Devices Remote Data/File Access

Personal communications (e-mail, chat, A/V)

World Wide Web ... and many other uses


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Program & File Sharing

(Software PackagesLicense copies)

Network Resources Sharing(ResourcesPrinter, Plotters, Storage Devices etc.)

Data Base Sharing

(Redundancy, Integration, Integrity, Standardization)

Economical Expansion of the PC Base

(Adding inexpensive Diskless Workstations etc.)

Advantages of Networking


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Ability to use network software

(Email, GroupwareUsers interact and coordinate activities)

Centralized Management

(Consolidation at the corporate level)

Security

(Restrictions & Restricted Access to Resources

Access to more than one O. S.(More than one O.S. - Front end and Back end

Enhancement of the Corporate Network

(Can Change structure of the organization Physical, Logistically)

Advantages of Networking


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A networkis simply a collection of computers or other hardwaredevices that are connected together, either physically orlogically, using special hardware and software, to allow them toexchange information.

Networkingis the processes of designing, implementing,upgrading, managing and otherwise working with networks andnetwork technologies.

Introduction To Networking


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Purpose Of Networking

Share Hardware, Software & Data


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Purpose Of Networking

Mail Services Internet


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There are two major ways to classify a

network:

The transmission technology

The size of the network

Classification Of Network


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Transmission Technologies

Simplex transmission is asingle one-way basebandtransmission.

It is also calledunidirectional becausethe signal travels in onlyone direction.

An example of simplex

transmission is the signalsent from the cable TVstation to the hometelevision.

Simplex Transmission


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This means that only one

side can transmit at a time.

Two-way radios, such as

Citizens Band (CB) andpolice/emergency

communications mobile

radios, work with half-

duplex transmissions.


Half-Duplex Transmission


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Traffic can travel in both

directions at the same time.

A regular telephone

conversation is an exampleof full-duplex

communication. Both

parties can talk at the same

time, and the person talkingon the other end can still be

heard by the other party

while they are talking.


Full-Duplex Transmission


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Network Size

We can also classify networks based on

their physical size.

Different technologies may be usedbased on the size of the network.

We can determine the type of network

based on the physical distance that thenetwork covers.


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Network Size

Interprocessor

Distance

Processors

located in same

1 m Square Meter

10 m Room

100 m Building

1 km Campus

10 km City

100 km Province

1000 km Continent

10,000 km Planet

Personal Area Network

Lan Area Network

Metropolitan Area Network

Wide Area Network

The Internet


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HOW BIG ARE NETWORKS ?

Networks can be divided into three categories based ongeographical area covered:

MANs : METROPOLITAN AREA

NETWORKS.

WANs : WIDE AREA

NETWORKS.

LANs : LOCAL AREA NETWORKS.


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TYPES OF NETWORKS

PEER TO PEER

CLINET / SERVER NETWORK

LAN

WAN

MAN

INTERNET


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Peer-to-Peer Networks

In a peer-to-peer network,the networked computersact as equal partners, orpeers, to each other.

As peers, each computercan take on the clientfunction or the serverfunction alternately.

Examples: kaaza, bittorrents etc.


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Client/Server Networks

In a client/server networkarrangement, networkservices are located in adedicated computer whoseonly function is to respond to

the requests of clients.

The server contains the file,print, application, security,

and other services in acentral computer that iscontinuously available torespond to client requests.


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Local-Area Networks (LANs)

A local-area network (LAN)can connect manycomputers in a relativelysmall geographical areasuch as a home, an office,

or a campus.

It allows users to accesshigh bandwidth media like

the Internet and allowsusers to share devices suchas printers.

M li A N k (MAN )


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Metropolitan Area Networks (MANs)

The network size falls intermediate between

LANs and WANs.

Metropolitan Area Networks or MANs are

large computer networks usually spanning acampus or a city. Eg: ATMs
http://www.erg.abdn.ac.uk/users/gorry/eg3561/intro-pages/lan.htmlhttp://www.erg.abdn.ac.uk/users/gorry/eg3561/intro-pages/wan.htmlhttp://en.wikipedia.org/wiki/Computer_networkhttp://en.wikipedia.org/wiki/Campushttp://en.wikipedia.org/wiki/Cityhttp://en.wikipedia.org/wiki/Cityhttp://en.wikipedia.org/wiki/Campushttp://en.wikipedia.org/wiki/Computer_networkhttp://www.erg.abdn.ac.uk/users/gorry/eg3561/intro-pages/wan.htmlhttp://www.erg.abdn.ac.uk/users/gorry/eg3561/intro-pages/lan.html


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Wide-Area Networks (WANs)

A WAN, as the name implies, isdesigned to work over a largerarea than a LAN.

A WAN uses point-to-point orpoint to multipoint, serialcommunications lines.

Point-to-point lines connect only

two locations, one on each sideof the line. Point-to-multipointlines connect one location onone side of the line to multiplelocations on the other side.


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INTERNET

DATES BACK TO 1960s

USES PACKETS SWITCHINGTECHNOLOGY

USES SPECIAL PURPOSE DEVICES

TYPES OF INTERNET CONNECTIVITY

POTS ISDN

CABLE MODEM

SATELLITE COMUNICATION

DSL


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Concept of Internet , Intranet and extranet

Internet

This is the world-wide networkof computers accessible to anyonewho knows their Internet Protocol (IP) address - the IP address isa unique set of numbers (such as 209.33.27.100)that defines the computer's location

Intranet

This is a network that is not available to the world outside of theIntranet. If the Intranet network is connected to the Internet, theIntranet will reside behind a firewall and, if it allows access from theInternet, will be an Extranet. The firewall helps to control accessbetween the Intranet and Internet to permit access to the Intranetonly to people who are members of the same company or organization.

ExtranetAn Extranet is actually an Intranet that is partially accessible toauthorized outsiders. The actual server (the computer that serves upthe web pages) will reside behind a firewall. The firewall helps to controlaccess between the Intranet and Internet permitting access to theIntranet only to people who are suitably authorized.


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THE NETWORK TOPOLOGY

The network topology defines the way inwhich computers, printers, and other

devices are connected.


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Main Types of Topologies

BUS OR LINEAR

STAR

RING OR STAR WIRED RING

MESH

TREE


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BUS TOPOLOGY

A linear bus topology consists of a main run of cable

with a terminatorat each end.

All nodes (file server, workstations, and peripherals)

are connected to the linear cable.
http://fcit.usf.edu/network/glossary.htmhttp://members.tripod.com/barhoush_2/glossary.htmhttp://members.tripod.com/barhoush_2/glossary.htmhttp://fcit.usf.edu/network/glossary.htm


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PROS & CONS OF BUS

PROS Bus is easy to use and understand and inexpensive It is easy to extend a network

CONS Entire network shuts down if there is a break in the main

cable.

Difficult to identify the problem if the entire networkshuts down.

Not meant to be used as a stand-alone solution in a

large building.


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STAR TOPOLOGY

A star topology linksthe computers byindividual cables to acentral unit, usually a

hub.


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PROS AND CONS OF STAR

PROS

Easy to install and wire.

No disruptions to the network.

Easy to detect faults and to remove parts.

cons

Requires more cable length than a linear topology.

If the hub or concentrator fails, nodes attached are disabled.

More expensive than linear bus topologies.


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STAR WIRED TOPOLOGY

A star-wired ring topology may appear (externally) tobe the same as a star topology. Internally, the MAUof a star-wired ring contains wiring that allowsinformation to pass from one device to another in a

circle or ring .

Topology
http://members.tripod.com/barhoush_2/glossary.htmhttp://members.tripod.com/barhoush_2/glossary.htm


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A DISADVANTAGE OF A TOKEN RING IS IF ONE

COMPUTER IS BROKEN OR DOWN, THE MESSAGE

CANNOT BE PASSED TO THE OTHER COMPUTERS.

Topology


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PROS & CONS OF STAR WIRED

PROS

One computer cannot monopolize the network.

It continue to function after capacity is exceeded but thespeed will be slow.

CONS

Failure of one computer can affect the whole network.

It is difficult to troubleshoot.

Adding and removing computers disrupts the network.


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MESH TOPOLOGY

In a mesh topology,each computer onnetwork has

redundant data paths.The mesh topologyprovides faulttolerance-if acomponent fails, data

can travel alongalternate path.


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PROS & CONS OF MESH

PROS

The load on any given access point is not asgreat as it would be with any other wired

network. Very flexible in nature

CONS Implementing the mesh topology is expensive

and difficult.


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TREE TOPOLOGY

A treetopologycombines

characteristics of linear busand startopologies.


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PROS & CONS OF TREE

PROS

Point-to-point wiring for individual segments

CONS

Overall length of each segment is limited bythe type of cabling used.

If the backbone line breaks, the entire segmentgoes down.

More difficult to configure and wire than othertopologies.


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Data Transmission

Successful transmission of data depends on:The quality of the signal being transmitted

Characteristics of the transmission medium

Data rate bits per second in data

communicationsBandwidth bandwidth or signal is constrainedby the transmitter and the nature of thetransmission in cycles per second or hertz

Noise

Average level of noise over thecommunication path.

Error rate rate at which errors occur whereerror in 1 or 0 bit occurs


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Basic transmission medium concepts

Medium

Guided Unguidedtwisted pair, coaxial cable,and optical fiber

satellite, laser, and wireless

transmissions

T i d P i C bl


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Twisted Pair Cables

Twisted-pair is a type of cabling that is used for telephonecommunications and most modern Ethernet networks.

A pair of wires forms a circuit that can transmit data. The pairs aretwisted to provide protection against crosstalk, the noise generatedby adjacent pairs.

There are two basic types, shielded twisted-pair (STP) andunshielded twisted-pair (UTP).


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Coaxial cable (1)

Widely installed for use in business and

corporation Ethernet and other types of LANs.

Physical Descriptions:

Covered by sheath material

Outer conductor is braided shielded (ground)

Separated by insulating material

Inner conductor is solid copper metal

Optical Fibers


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Optical Fibers

Fiber-optic cable is anetworking medium capableof conducting modulatedlight transmissions.

Fiber-optic refers to cablingthat has a core of strands ofglass or plastic (instead ofcopper), through which lightpulses carry signals.

Signals that represent dataare converted into beams oflight.


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Wireless Transmission

If the cost of running cables is too high or computers need to be movable

without being tethered to cables, wireless is an alternative method ofconnecting a LAN.

Wireless networks use radio frequency (RF), laser, infrared (IR), and

satellite/microwaves to carry signals from one computer to another without a

permanent cable connection.

CO O O G C S


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COMMON NETWORKING DEVICES

A HUB is a device thatis used to extend a wireto allow more devices

to communicate with

each other.


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HUB

A hub is a device used to connect a PC to the network.

The function of a hub is to direct information around the network

and facilitating communication between all connected devices.

A hub joins multiple computers (or other network devices) togetherto form a single networksegment. On this network segment, all

computers can communicate directly with each other.
http://compnetworking.about.com/library/glossary/bldef-segment.htmhttp://compnetworking.about.com/library/glossary/bldef-segment.htm


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MODEMS

An electronic device used for computer communications and Allows

data transfer.

A modem does for computers what a telephone does for humans. Just

as a telephone set allows two humans to speak to one another over

telephone wires, a modem allows two computers to speak to each other

over telephone wires.


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Token Ring Cards :

Token Ring cards generally have a nine pin DIN type connector to

attach the card to the network cable.

Switch

A device that is use to extend a wire to allow more devices to

communicate with each other

Electrically amplify the signal as it moves from one device to

another Memorize addressing of computers and send the information

to the correct location


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Usually configured with 8, 12, or 24 RJ-45 ports

Often used in a star or star-wired ring topology

Sold with specialized software for port managementAlso called hubs

Usually installed in a standardized metal rack that also may store

netmodems, bridges, or routers


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Repeaters

The repeater electrically amplifies the signal it receives and

rebroadcasts it

It retimes and regenerates the signals to proper amplitudes and

sends them to the other segments.

Repeaters require a small amount of time to regenerate the signal.

This can cause a propagation delay which can affect network

communication


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Bridges

To segment a large network into two smaller, more efficient networks.Connects 2 networks with different Topologies

A bridge monitors the information traffic on both sides of the network

so that it can pass packets of information to the correct locationThe bridge is like a traffic cop at a busy intersection during rush hour

A bridge reads the outermost section of data on the data packet, to tell

where the message is going


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Routers

A router translates information from one network to another;Routers select the best path to route a message, based on the

destination address and origin.It is similar to a super intelligent bridge

Direct signal traffic efficientlyRoute messages between any two protocols/Topologies.

Route messages between linear bus, star, and star-wired ring topologies

Route messages across fiber optic, coaxial, and twisted-pair cabling

Protocols


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Protocols

A protocol is a formalized set of procedural rules

for the exchange of information and for the interactionsamong the network's interconnected nodes. A networksoftware developer implements these rules in softwaremodules that carry out the functions specified by the

protocol. Whereas a router can connect networks onlyif they use the same protocol and address format, agateway converts addresses and protocols toconnect dissimilar networks.


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WHY DO I NEED A STANDARD ?

Many types of connection media :telephone lines, optical fibers,

cables, radios, etc.

Many different types of machines andoperating systems

Many different network applications

O SI

need fora STANDARD incommunicationtechnology:


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WHAT STANDARD MEANS ?

How many volts pulse is a 0 and 1 ?

How to determine the end of a message ?

How to handle lost messages ? How many bits for different data types ?

Integers/Strings, etc.; are ASCII chars ?

How machines are identified ?

How to find the way to reach a machine ?

How applications speaks together through the

network ?

Agreements must be at many levels ...

THE ISO/OSI MODEL


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THE ISO/OSI MODEL

ISO (the International Organization for Standardisation) hasdeveloped a standard model for communications, called the

OSI Model(Open Systems InterfaceModel)

MODEL= Its only theory! In fact is not yet implemented.

OPEN SYSTEM means that it can communicate with any othersystem that follows the specified standards, formats and semantics.

PROTOCOLS give the rules that specify how the different partiesmay communicate.

There are two general types of protocols:connection-orientedconnectionless


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OSI Model Overview contd


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OSI Model Overview contd

The Layers at Work


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The Layers at Work

Supports the communication between

applications over the network

Presents data to the receiver

in a form it recognises

Establishes a connection and

terminates it when no longer required

Acknowledges the flow of data

including re-transmission where required

Adds the appropriate networkaddresses to packets

Adds the MAC addresses to packets

Transmits the data on the medium

NODE A

Sending Device

NODE B

Receiving Device

Layer 7

Application Layer

Layer 6

Presentation Layer

Layer 5

Session Layer

Layer 4

Transport Layer

Layer 3Network Layer

Layer 2

Data Link Layer

Layer 1

Physical Layer

Layer 7

Application Layer

Layer 6

Presentation Layer

Layer 5

Session Layer

Layer 4

Transport Layer

Layer 3Network Layer

Layer 2

Data Link Layer

Layer 1

Physical Layer


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Standard Protocols


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Standard Protocols

TCP/IP - Transmission Control

Protocol -Internet Protocol

IMAP - Internet Message AccessProtocol

FTP - File Transfer Protocol

SMTP - Simple Mail Transfer Protocol

UDP - User Datagram Protocol

http - Hyper Text Transfer Protocol

APPLICATIONS


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APPLICATIONS

Marketing and Sales

Financial services

Manufacturing

Electronic messaging

Information services

Teleconferencing

Others


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