itbm networking architectire.doc

8/12/2019 itbm networking architectire.doc

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A !etwork is a group of systems that are connected to allow sharing of resources such as files or

printers, or sharing of ser"ices such as internet. #he physical connection between the

systems$de"ices in a network is established using either cable media or wireless media. !etworkde"ices that originate, route and terminate the data are called network nodes. A client is a de"ice

that sends re%uest to the ser"er of the network and a ser"er is a computer system$de"ice that

recei"es the re%uest, processes it, and returns the re%uested information back to the client.!etwork architecture is a framework of the network&s physical components and their functionalorgani'ation and configuration, its operational principles and procedures, as well as data

formats used in its operation. (ased on the framework there are two types of network

architectures:

Centralize Arc!itect"re

#istrib"te Arc!itect"re

6$% Centralize Arc!itect"re

#he first computers were large, expensi"e, and difficult to manage. #he computer executed one)ob at a time. #erminals, which came later, pro"ided the user with a new mechanism to interact

with the centrali'ed computer. #hese terminals, howe"er, were merely input$output de"ices that

had no independent processing power. All processing took place on the central computer* henceit is named as the centrali'ed computing. !etworks, therefore, ser"ed little purpose other than to

deli"er commands to and get results from the powerful centrali'ed system. #o this day, large

mainframe systems are still being operated around the world, most often by go"ernments and

large corporations. #hese early computing models worked well in large organi'ations that could)ustify the need for these expensi"e computing de"ices. +owe"er, one of the drawbacks was that

the mainframes were not flexible in their placement some were the si'e of a large room- and did

not scale down to meet the needs of smaller organi'ations. !ew ways of sharing information

were necessary to allow computing power to be shared efficiently on smaller networks.

A centralize net&'r(is a network in which most communications are routed from one ma)orcentral hub$system. In the centrali'ed network computing model, the clients with low or no

processing capabilities use the resources of a highcapacity ser"er to process information. #he

clients only connect to the ser"er and not to each other. igure /.0 shows a centrali'ed network

computing model. A client in need of ser"ices sends the re%uest for the same to the ser"er whichprocesses the re%uest and responds back to the client with the re%uired ser"ice. It offers

greater security because all information processing is controlled in a central location. In addition,

if one terminal breaks down, a user can go to another terminal and all of the files will still beaccessible. Depending on the system, they may e"en be able to resume their session from the

point they left. Another benefit of centrali'ed networks is the ease of maintaining accurately

updated lists of data that can be easily accessed from all points.

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)ig"re 6$%: an e*a+,le '- centralize net&'r( arc!itect"re

#raditionally, this type of networking was only found in Enterprise 1e"el (usinesses. In recenttime, due to reduced ser"er and network costs of centrali'ed network architecture, this type of

computing deployed in many smaller and medium si'ed businesses.

C!aracteristics '- a Centralize Net&'r(

A centrali'ed system consists of a large data center that hosts all ser"er resources.

2oftware upgrades can be done from a centrali'ed location.

#he data center incorporates powerinsulating de"ices such as Uninterruptible 3ower

2upply U32- and 4hotsites5 or 4coldsites5 contingencies.

(usiness re%uirements associated with reducing cost and security re%uirements are usually the

dri"ing forces behind centrali'ed networks. #here are mainly two ways of centrali'ing network

implementation i.e. 6lient ser"er model and +osted client model. Client./erver 0'el

1et us consider figure /.0 which is a clientser"er model. #he clients need different

ser"ices for which they send re%uests to the central hub or ser"er. #he ser"er upon

recei"ing the re%uest processes the re%uest and responds accordingly to the client. 2o wemay say that a 4client5 is a computer system that initiates communication with the ser"er

to a"ail some resources. A 1ser"er5 is the one that shares its resources with client

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Workstation


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computer. #his sharing of resources is also known as timesharing because multiple

applications are allowed to share the same resources at the same time. #his

communication between the clients and the ser"er always follows a re%uestresponsenetworking pattern thus making it compulsory for the computers to ha"e a common

language and common rules of communication, defining as 4communications protocol5.

)ig"re 6$2: Re3"est.Res,'nse net&'r(ing bet&een a client an t!e server

Client /erver Envir'n+ent

#his en"ironment is comprised of a ser"er which pro"ides system resources

processing power, storage, software, applications, ser"ices etc- to se"eral connectedclients.

#he ser"er controls what a user has access to. (oth software and data can be

accessed by any of the clients. #he ser"er contains all software. e.g. If one wants to

upgrade the most recent "ersion of 7ord, he has to do it once on the ser"er and thene"eryone can use it. 1ikewise with operating system or internet software etc can also

be shared.

#he ser"er can hold and protect all data.

H'ste.Client 0'el

Another method of centrali'ed computing is hostedclient model. In this model,processing and storage on powerful ser"er hardware located in a data center, rather than

in a local office. 8rgani'ations are relie"ed of many responsibilities in owning and

maintaining an information technology system.

A,,licati'ns '- Centralize Net&'r(s

AT0s: A#9 machine is an example of centrali'ed networking with which e"eryone is

familiar in using. A#9s function as terminals. All processing is done on the mainframe

computer to which the A#9s are connected.

P"blic Instant.0essengers: 9ost of the 3ublic Instant9essenger platforms use the

centrali'ed network architecture to pro"ide ser"ices to the users.

4''gle Cl'" C'+,"ting: oogle 6loud computing is also used for employees5

centrali'ed networks.

Avantages

Ad"antages of centrali'ed network architecture are:

4

CLIENT SERVERNETWO

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Centralize ata +anage+ent: In a centrali'ed network, data is stored on the ser"er for

increasing the reliability of data because all data modifications are stored at a central

location. Hig! level '- sec"rit5: #he centrali'ed network computing model is a highly secured

network model because network security can be implemented and monitored centrally

from the ser"er.

C'st e--ectiveness: #he o"erall cost of setting up a centrali'ed architecture is "ery low.

Li+itati'ns

6entrali'ed network architecture has the following limitations:

L'& ,er-'r+ance an net&'r( s,ee: A single ser"er manages numerous re%uests

simultaneously for increasing network traffic and conse%uently reducing the speed for the

performance of the network.

Central ,'int '- -ail"re: #he ser"er is the central and only place for storing data and

processing all client re%uests. If the ser"er fails, the whole network collapses.

I+,'rtant C'nsierati'ns

A centrali'ed system is considered only if prere%uisites are the following:

#ata center !ar&are c'sts #he cost of installing highend ser"ers and clusters in the

data center against the administrati"e cost sa"ings of centrali'ing the ser"ers must be

weighed. It is recommended that the backend ser"ers are clustered to build higha"ailability and redundancy into the system, but this in"ol"es greater costs up front.

+owe"er, these costs may be more than offset by reductions in operational costs,

infrastructure costs, reduced downtime, and greater scalability. C'ntingenc5 ,lanning 7hen you ser"er and data resources across the organi'ation are

centrali'ed, the possible single points of failure are increased. 6ontingency plans must be

formulated.

O,erati'nal an a+inistrative c'st re"cti'ns 6entrali'ing ser"er resources reduce

operational costs because ser"ice capacity and growth are achie"ed with better use of

resources. It also reduces infrastructure costs associated with storage and backupre%uirements.

#ata st'rage 7ith larger centrali'ed data "olumes, more reliable storage systems must

be used to impro"e the integrity of data. In addition, by reducing the complexity of ser"er

infrastructure, one can more readily restore ser"ices and data when a failure occurs.

/ec"rit5 A centrali'ed model gi"es easier security management, thus it gi"es a greater

degree of control. #his control makes it easier for security staff to maintain uptodate

"irus signatures and take timely action in response to security incidents. Another

ad"antage of a centrali'ed design is that it locates your ser"ers in a data center which youcan physically secure.

6$2 #istrib"te Arc!itect"re

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Distributed 6omputing is a trend in modern day business en"ironments. #his is the opposite of

centrali'ed computing, which was pre"alent during the early days of computing. Distributed

computing is the allocation of resources both in hardware and software to each indi"idualworkstation or office location. In contrast, centrali'ed computing exists when the ma)ority of

functions are carried out or obtained from a remote centrali'ed location. #he distributed network

computing model allows all network computers to take part in processing but at their respecti"eends separately. #his model allows sharing data and ser"ices but does not help the other network

computers in processing. In this network model, a processingintensi"e task is broken into a

subset of tasks and distributed among multiple nodes. #he nodes work on their indi"idual subsetsof tasks. #he following figure figure /.;- shows the distributed network computing model:

)ig"re 6$: A istrib"te net&'r( arc!itect"re

A distributed computer system has many benefits o"er a con"entional centrali'ed network.Desktop computers ha"e ad"anced so rapidly that their potential performance far exceeds the

re%uirements of most business applications. #his results in most desktop computers remaining

idle in relation to their full potential-. A distributed system can utili'e the potential of thesesystems to maximi'e efficiency. +owe"er, it is debatable whether these networks increase o"erall

effecti"eness. All computers ha"e to be updated indi"idually with new software, unlike a

centrali'ed computer system. Distributed systems still enable file sharing and all computers canshare peripherals such as printers and scanners as well as modems, allowing all the computers in

the network to connect to the internet.

A collection of distributed computers systems are components of a larger computer network, held

together by local stations of e%ual importance and capability. #hese systems are capable ofrunning independently each other.

C!aracteristics '- a #istrib"te Net&'r(ing /5ste+:

6

CENTRAL

LOCATION

INTERNET


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Real.ti+e ,r'cess c'ntr'l

Aircraft control systems

Industrial control systems

Avantages '- #istrib"te Net&'r( Arc!itect"re

/calabilit5: Enterprise solutions that rely on a single enterprise ser"er ine"itably suffer

from performance issues as the enterprise grows and the ser"er is o"erwhelmed.9oreo"er, single ser"er solutions are highly susceptible to network failures.

E--icienc5: 2ecurity managers control the flow of data and decisionmaking. 1ocal data

and decisions can be transmitted to each indi"idual site, minimi'ing network bandwidth,

and allowing global managers to focus on truly global issues. At the same time, centrallylocated global managers can easily run reports, make changes, and "iew the status oflocal sites without needing to login to multiple separate systems.

C'st: 2er"ers and software at each local site can be appropriately si'ed to meet the

specific needs of each site, without re%uiring installing an expensi"e ser"er at e"en the

smallest sites.

Reliabilit5: Distributed !etwork Architecture is much more tolerant of network and

hardware failures than a single ser"er approach.

I+,'rtant C'nsierati'ns

O,erati'nal an a+inistrative c'sts: Distributed networking systems re%uire more

ser"ers and so result in higher operational and administrati"e costs.

#ata st'rage: 7ith distributed ser"ers, the ser"ice infrastructure is more complex,

which makes it more difficult to restore ser"ices and data when a failure occurs.

Net&'r( c'nnecti'ns: or remote offices, it is recommended that the network

connection to the hub site or data center be no less than


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and body mo"ement. Data communication entails exchanging data or information "ia the

electronic media. It is the tra"elling of computer information or data from one point to another

by means of electrical or optical transmission system. #his system often is known to us as the

data communication networks. In today&s computing world, data can mean facts, statistics, "oice

and other information that is digitally coded and also intelligible to a "ariety of electronic

machines.

#he key technology of the information age is computer communication through networks. #he

"alue of highspeed data communication network is that it brings the message sender and

recei"er closer together in matter of seconds. Data communication and networking is a truly

global area of study. It makes possible more efficient use of computers and impro"es the day to

day control of your )ob by pro"iding faster and more secured information flow. #he information

society where information and intelligence are the key dri"ers of personal, business and national

success- has played a ma)or role in digital organi'ation. Data communication is the principle

enabler of the rapid information exchange and will become more important than the use of the

computer in future.

!ow once we ha"e understood what communication and communication system means, we will

ha"e to study and understand what this system is made of, how it works and gets its ad"antages.

It is necessary to ha"e a pathway or media to transmit the data from one point to the other. #he

term media means the de"ice or the group of de"ices that transmits the "oice or the data form

one point to another. 9any different types of transmission media are in use today for example:

wired transmission e.g. copper wire, glass or plastic cables, which is called fiber optic cables- or

wireless transmission e.g. radio, infrared, microwa"e, or satellite-. #here are two types of media,

one is known as guided media and another is known as radiated media. In guided media the

messages flow through the physical media like twisted pairwire, coaxial cable fiber optic cables,

and the media guided is the signal. In radiated media messages are broadcasted through the air

with the help of different wa"es > e%uipments at "arious le"els of data transmission, such as

infrared, microwa"e, or satellite.

7asis '- /electi'n '- C'++"nicati'n 0ei"+

Digital data can be transmitted o"er many different types of media. 2electing a transmission

medium is helped by comparing transmission needs against the medium5s features. our

important criteria for selecting the type of transmission medium are:

0. 7an&it!: (andwidth is the maximum fre%uency range that can be practically

supported by a medium. #his is usually expressed in k+' or 9+'. or example, analog

transmission of human speech typically re%uires a bandwidth of ? kilo +'. Data rate is

another network feature, which is related to bandwidth. #he data rate specifies the

maximum number of bits per second bps- that can be transmitted. or example, a data

rate of 0@ mbps means that 0@ million bits of data can be transmitted in each second.

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(ecause of their ob"ious relationship, the terms data rate and bandwidth are sometimes

used alternati"ely. (ecause of distortion factors, bandwidth and data rate are usually

in"ersely related to the distance of communication.

. C'st$ #wo types of cost are rele"ant: i- the cost of installing the medium, including the

specific e%uipment that may be needed for the medium to work, and ii- the cost ofrunning and maintenance of the medium and its e%uipment. #here is usually a need for

tradeoff between bandwidth, distance > cost.

;. Reliabilit5$ 2ome media, by their physical nature broadcast data more consistently than

others. 1ow reliability generally means to a higher number of errors in transmission of

data, which needs to be balanced against the potential cost of reco"ering from the errors

e.g., retransmission, more complex hardware and software-.

?. C'verage$ #he physical characteristics of a medium dictate how long a signal can tra"el

in it before it is distorted beyond detection. #o co"er greater areas, repeaters are needed torestore the signal, and this increases the costs of maintenance > setting up of the

medium.

6$$% Wire C'++"nicati'n 0ei"+

7ired communication medium is also known as the guided communication media, in which we

guide the electromagnetic wa"es through a solid medium of "arious kinds a"ailable with us.

7ith the ad"ancement in technology, the wired medium has used newer kinds of wires to

transmit the data such as copper twisted pair, copper coaxial cable, and optical fibre. #he

characteristics and %uality of a data transmission are determined both by the characteristics of the

medium and the characteristics of the signal. In the case of guided media, the medium is of more

importance in determining the characteristics of transmission of the medium.

T5,es '- Wire 0ei"+

T&iste.Pair Cable

A twisted pair consists of two insulated copper wires arranged in a standard spiral pattern.

A wire pair acts as a single link of communication. #ypically, a number of these pairs are

wrapped under a shielding sheet after bundling them together. 8"er longer distances,

cables may contain hundreds of pairs. #he twisting tends to lessen the crosstalk nosinessbetween two ad)acent pairs in a cable. !eighboring pairs "ary in their twist lengths to

reduce the crosstalk interference. 8n longdistance links, the twist length generally "aries

between < > 0


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)ig"re 6$ 8: A t&iste ,air &ire

9arieties '- T&ister.Pair Cable

#wisted pair comes in two "arieties: unshielded and shielded. Unshielded twisted pair

U#3- is the general wire commonly used as the telephone wire. #his is the mostinexpensi"e of all the transmission media commonly used for local area networks and is

easy to work with and also it is easy to install. Unshielded twisted pair is affected by

external electromagnetic interference, including electromagnetic interference from a

nearby twisted pair or from the disturbance generated in the neighboring en"ironment.

2o, a metallic shield )acket is used to impro"e the characteristics of this medium and thus

to protect it from interference. #his shielded twisted pair 2#3- pro"ides better

performance at much higher data rates. +owe"er, it is more costly and more difficult to

work with than the unshielded twisted pair.

Table 6$%: C!aracteristics '- i--erent t5,e '- t&iste ,air &ires

T&iste ,air T5,e /!ieling Trans+issi'n Rate

#ype 0 2hielded ? 9bps

#ype 6ombination ? 9bps

#ype ; Unshielded 0@ 9bps

#ype ? Unshielded 0/ 9bps

#ype < Unshielded 0@@ 9bps

C'a*ial Cable

6oaxial cable, like twisted pair consists of two conductors, but is constructed in a different

way. It allows operation o"er a wider range of fre%uencies and distances. It consists of a

hollow outer cylindrical conductor that surrounds a single inner wire conductor. #he inner

conductor is held by solid dielectric material or by regularly spaced insulating rings. #he

outer conductor is co"ered with a shield. A single coaxial cable has a width from 0 to . microwa"e. (y using fre%uency

di"ision multiplexing, a coaxial cable can carry o"er 0@,@@@ "oice channels at a particular

point of time.

Trans+issi'n C!aracteristics

6oaxial cable is used to transmit both analog and digital signals. As it can be seen from

figure /.


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An optical fiber is a lean 0 the core. #he 4core5is the deepest section and consists of one or more

"ery thin strands, or fibers, made of plastic or glass. #he core has a diameter in the range of

G. Each fiber is surrounded by its own 4cladding5, a plastic or glass coating that has optical

properties different from those of the core. #he interface between the core and cladding

plays the role of a reflector to confine light that would otherwise get away from the core.

#he outermost layer surrounding the cladding fibers is known as the 4)acket5 .#he )acket is

composed of plastic and other material layer to protect against crushing, abrasion, moisture

and other en"ironmental dangers.

A,,licati'ns

8ne of the most considerable technological breakthroughs in the field of data transmission

has been the de"elopment of practical fiber optic communications networks. 8ptical fiber

already has a tremendous use in longdistance telecommunications, and its use in defence

related applications is on a rise. #he continuous impro"ements in performance and fall in

prices, together with the innate ad"antages of optical fiber ha"e made it much more suitable

for local area networking. #he following characteristics distinguish optical fiber fromcoaxial cable or twisted pair wire.

o 4reater ca,acit5: #he potential bandwidth, and thus the data rate of optical fiber is

immense. Data rates of hundreds of bps o"er tens of kilometers ha"e been easily

attained. #his when compared to the practical maximum of hundreds of 9bps o"er about

0 km for coaxial cable and )ust a few 9bps o"er 0 km or up to 0@@ 9bps to 0 bps o"er

a few tens of meters for twisted pair, shows us how an optical fiber is gaining importance

in modern day networking.

o

/+aller size an lig!ter &eig!t: 8ptical fibers are considerably thinner than bundledtwisted pair cable or coaxial cable at least an order of magnitude thinner for almost same

amount of information transmission capacity. or cramped spaces in buildings and

underground along public rightsofway, the ad"antage of small si'e is substantial. At

the same time the reduction in weight reduces structural support re%uirements for

installation of optical fiber network.

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o L'&er atten"ati'n: Attenuation is significantly lower for optical fiber than for twisted

pair or for coaxial cable and is constant o"er a wide range.

o Electr'+agnetic is'lati'n: 8ptical fiber systems are not affected by external

electromagnetic fields. #hus the system is not susceptible to cross talk, impulse noise >

interference. (y the same way, fibers do not radiate energy, so there is little or nointerference with other e%uipment. #here is also a high degree of protection from

ea"esdropping. In addition, fiber is inherently difficult to tap from another source.

o 4reater re,eater s,acing: ewer repeaters mean lower cost and fewer sources of error.

#he performance of optical fiber systems from this point of "iew has been steadily

impro"ing. Hepeater spacing in the tens of kilometers for optical fiber is common, and

repeater spacing of hundreds of kilometers ha"e been demonstrated. 6oaxial and twisted

pair systems generally ha"e repeaters in e"ery few kilometers.

Trans+issi'n C!aracteristics

8ptical fiber transmits a signalencoded beam of light by means of total internal reflection.

#otal internal reflection can occur in any transparent medium that has a higher index of

refraction than the surrounding medium. In effect, the optical fiber acts as a wa"eguide for

fre%uencies in the range of the infrared and "isible spectra.

)ig"re 6$6: #e,icting +'es '- trans+issi'n t!r'"g! )iber O,tic Net&'r(

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#he main types of wireless media are: radio wa"e, microwa"e and infrared.

Rai' Wave Trans+issi'n /5ste+s

#he fre%uency range of Hadio wa"es is between 0@ =+' and 0 +'. In electromagnetic

spectrum range between 0@ =+' and 0 +' is also called radio fre%uency. Hadio wa"esare of following types:

2hort wa"e

ery high fre%uency +- and 9 radio

Ultra high fre%uency U+- radio and #ele"ision

9ost radio fre%uencies are regulated. Hegulated fre%uencies ensure clear radio

transmission. Hadio wa"es can broadcast 8mni directionally or directionally. arious

types of antennas can be used for broadcasting. 2ome of most commonly used antennas

are:

8mni directional towers

+alf wa"e dipole

Handom length wire

(eam

or computer network applications, radio wa"es fall into three categories:

0. 1ow power, single fre%uency. +igh power, single fre%uency

;. 2pread spectrum

0icr'&ave Trans+issi'n /5ste+

9icrowa"e system uses lower gigahert' fre%uencies of the electromagnetic spectrum. #hese

fre%uencies are higher than radio fre%uencies. #hey produce better performance and

throughput. 9icrowa"e data communication systems are of the following types:

#errestrial

2atellite

#errestrial microwa"e uses directional parabolic antennas to send and recei"e signals.

9icrowa"e links connect separate buildings where cabling is difficult or expensi"e. 2atellite

systems transmit signals between directional parabolic antennas. 9ain difference between

satellite system and terrestrial system is that in a satellite system one antenna is on a satellite

i.e in geosynchronous orbit about


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microwa"e systems can reach the most remote places on earth and communicate with mobile

de"ices. 1A! sends a signal through cable media to antenna, which beams the signal to the

satellite in orbit abo"e the earth. #he orbiting antenna then transmits the signal to another

location on the earth or to another satellite if the destination is on the opposite side of the

earth- which then transmits to a location on the earth. #here are some propagation delays

which may range from .< to < seconds. #he table shows some features of the two microwa"e

data communication systems.

Table 6$ 2: 7asic )eat"res '- T&' &ave 0icr'&ave /5ste+s

Heference: Bulletin of Information Technology; Wireless: A new paradigm by Ashwani ush ! ".. #hauhan

In-rare /5ste+s

Infrared media uses infrared light to transmit signals. 1ight emitting diodes 1ED- transmit

the signals and photodiodes recei"e the signals. rom electromagnetic spectrum infrared uses

terahert' range high fre%uency range-. #he remote controls of different electronic de"ices

can be used in this technology. #hough infrared signals ha"e a good throughput, but problem

is that they cannot pass solid materials and they are also diluted by strong light sources.

Infrared allows both point to point and broadcast transmission. 3oint to point allows better

transmission rate, but de"ices must be within its location and on the other side, broadcasting

gi"es more flexibility but rate of data transfer is slow. #he table gi"en below represents basic

features of two types of infrared transmission.

P'int t' P'int: Infrared beams can be tightly focused and directed at a specific target.

6areful alignment of transmitter and recei"er is re%uired.

7r'acast: (roadcast infrared systems spread the signal to co"er a wider area and allow

reception of the signal by se"eral recei"ers. 8ne of the many ad"antages is mobility.

Table 6$: 7asic )eat"res '- T&' t5,es '- In-rare Trans+issi'n

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"eference: Bulletin of Information Technology; Wireless: A new paradigm by Ashwani ush ! ".. #hauhan

6$8 Internet Intranet an E*tranet

#he three terms that describe 4Internet #ype5 applications in organi'ations are Internet, Intranet

and Extranet. Although they rely on the same #63$I3 technologies, they differ in terms of the

le"els of access they allow to the "arious users both inside and outside the organi'ation.

Internet

An internet type application is built if you wish to expose information to e"ery internet user

around the world. It is built in using protocols such as +##3, 29#3 and #3. 2uch applications

are made to be customer friendly, e.g. bank transactions can now be made by a customer from

home. All he needs to do is simple access the application of the bank and carry out the

transaction that he wishes to perform.

Avantages '- t!e internet are:

6ommunication

Information Entertainment

2er"ices

Ecommerce

#isavantages '- t!e internet are:

#heft of personal information

2pamming

irus threat

3ornography

Intranet

If an application is built using 4Internet #ype5 protocols such as +##3, #3 and 29#3, but is

only accessible to employees working in a particular company, it is an Intranet application. #his

information is for internal use only and cannot be accessed by the public on the internet. Eg.

9o"ement of account information of all customers of a particular bank from paper to a web

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browser does not mean that the customers can access this information. #he 7eb (rowser can

only be accessed by the employees of that particular bank.

Avantages '- Intranet are:

7orkspace producti"ity in terms of %uick information exchange 2haring information to employees according to their need and re%uirement.

Impro"ed teamwork as certified users of a team can access information

6ross platform capability for U!IC, 9ac, 7indows, etc

#isavantages '- Intranet are:

2ecurity issues

Information has to be prearranged

6ost is high

E*tranet

#here are times when applications are made for the company5s intranet but need to be extended

to certain business partners or customers by the employees. 7hen you do this, you ha"e created

an extranet. It cannot be used by anyone else from outside the company except for those selected

people.

Avantages '- E*tranet:

1arge "olumes of data can be exchanged

3roduct catalogs can be exchanged with business partners

6ollaborations with other companies

3ro"ide ser"ices of one company to the employees of another company

#isavantages '- E*tranet:

#oo expensi"e

Difficult to maintain

2ecurity concerns

6$; Net&'r( Ter+in'l'g5

6$;$% R'"ters

A de"ice that transfers date between networks, thus creating an internetwork is called a router.

#he data lines of different networks are connected to one particular router. 7hen a particular

data packet arri"es at one of the lines, the router checks its address information to know its

ultimate destination. According to this information and the information a"ailable in the routing

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tables, the router directs the packet to its next destination in order to reach its ultimate

destination. #his packet is thus transferred from one router to another through the "arious

networks till it reaches its destination.

T5,es '- R'"ters

#he most commonly used routers are the ones used in homes or offices to access the web. 1arge

enterprises and businesses which need to high speed access use enterprise routers that are

connected by optical fibers. 6ommercial core routers which are used in the market these days

are:

i- Juniper !etworks5 #/?@ #C9atrixii- 6isco 2ystems 6arrier Houting 2ystems

)ig"re 6$


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introduced at one input port arri"es at all output ports. It is a non intelligent de"ice and it uses

symbols. It helps a lot to detect collisions.

/t're an )'r&ar

In this type of hub the information is stored before forwarding to the next hub. #here are somead"antages of store and forward hub as follows:

Intelligent decisions with respect to forwarding of packets can be made. #he packet can

be transferred only to that particular node where it is re%uired instead of all the nodes.

6ollisions will no longer take place.

#he band width limitation does not arise.

In the 82I layer, hubs are classified in the physical layer. 7ithout store and forwarding, the hubs

are unaware of the data that passes through them and of their source and destination addresses. It

simply recei"es the frames, regenerates the electric signals on bit le"el and broadcasts these

frames to all the nodes

.

)ig"re 6$=: #istrib"ti'n -r'+ a Parent H"b.

As seen in the figure, the parent is the hub while the entire children are the "arious nodes.

6$;$ 4ate&a5

During transferring of packets from one node to another, the networks may use different

protocols. A gateway is a de"ice which acts as protocol translators, signal translators or

impedance matching de"ices. #his protocol translator is basically used to interconnect with

different network protocols by performing the necessary protocol con"ersions.

A,,licati'n

#he gateway, in networking has plenty of applications. 8ne of them is its use in the

telecommunication industry. Due to telephone company mergers, the need to interconnect

networks based on different signaling standard arises. 29 based networks are interconnected

with I2?0. #hus, protocol con"ersion gateways are "ery useful and re%uired in such cases. Also,

22

3arent

Ci!"

Ci!"

Ci!"


23/27

as discussed earlier, a computer ser"er acting as a gateway node may also act as a firewall or a

proxy ser"er.

)ig"re 6$>: /tr"ct"ral re,resentati'n '- a 4ate&a5$

Internet t' Orbit ?IO2@ 4ate&a5

An I8 gateway is a machine or a de"ice which acts as a connector between computers

connected with the internet and systems that are orbiting the earth such as satellites and

spacecrafts. #his is done when the I8 establishes a stable ling between the network of

computers on the internet and the satellites. #his kind of technology was first introduced in

pro)ect +ermes.

%%$;$8 Re,eaters

Hepeaters are mostly used in the telecommunication industry. It is a de"ice which recei"es a

signal and retransmits at a higher power to co"er long distances. It is mainly used to increase the

range of the signal transmitted. #his is re%uired as the signal, that is transmitted, which suffers a

lot of losses. A drop in potential energy across the ends of the conductor that is proportional tothe current times in"erse of conductors conductance occurs due to losses in the form of heat

energy. #he light containing photons is also lost due to scattering and absorption. +ence,

repeaters are necessary.

T5,es '- Re,eaters

O,tical Re,eater: It recei"es light as input and also outputs light.

23


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.

LAN % LAN 2

)ig"re 6$%%: A brige c'nnecti'n t&' LAN

C!a,ter Hig!lig!ts:

Network architecture is a $ra%&'ork o$ t& n&t'ork(s )*si+a!

+o%)on&nts an" t&ir $,n+tiona! or-ani.ation an" +on/-,ration its

o)&rationa! )rin+i)!&s an" )ro+&",r&s as '&!! as "ata $or%ats ,s&" in its

o)&ration

A centralize net&'r(is a network in which most communications are routed from one

ma)or central hub$system.

Distributed network is a tr&n" in %o"&rn "a* ,sin&ss &niron%&nts Tis

is t& o))osit& o$ +&ntra!i.&" +o%),tin- 'i+ 'as )r&a!&nt ",rin- t&

&ar!* "a*s o$ +o%),tin- istri,t&" +o%),tin- is t& a!!o+ation o$ r&so,r+&s

ot ar"'ar& an" so$t'ar& to &a+ in"ii",a! 'orkstation or o+& !o+ation

#ata c'++"nicati'n +ei"+can be classified into wired and wireless and both ha"e

their own ad"antages and disad"antages.

Revie& B"esti'ns:

0. Discuss the importance of network architecture for business data communication.

. Discuss the benefits of studying network architecture as a management student.

;. Discuss different types of network architectures with their pros and cons.

?. 7hat is the impact of communication medium on data communicationK


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/. 7rite shot notes on:

a. +ub

b. ateway

c. Houter

d. Hepeater

Objective B"esti'ns:

L.0. W!ic! ,r't'c'l is "se -'r sening e+ail 'n t!e internet

a. 29#3

b. 2933

c. 2!93

d. #3

B$2 All '- t!e -'ll'&ing c'"l be liste as bene-its t' sellers s!'"l t!e5 c!''se t' sell via

t!e Internet EDCEPT:

a. the Internet is a powerful tool for customer relationship building.

b. the Internet is a more secure place to conduct transactions than in a retail

en"ironment.

c. the Internet reduces costs and increases speed and efficiency.

d. the Internet offers truly global commerce.

L.;$ &!ic! 'ne '- t!e -'ll'&ing is "se t' c'++"nicate bet&een i--erent net&'r(s

a. AD21

b. +D21

c. ateway

d. 9odem

B$8$ W!ic! '- t!e -'ll'&ing evice c',ies electrical signals -r'+ 'ne Et!ernet t' an't!er

a. bridge

b. repeater

c. hub

d. passi"e hub

B$; W!at ',erates in t!e #ata Lin( an t!e Net&'r( la5er

a. !I6

b. (ridge

c. (router

d. Houter

26


27/27

B$6 W!ic! '- t!e -'ll'&ing is t!e l'gical t','l'g5

a. (us

b. #ree

c. 2tar

d. (oth A and (

B$< T!e stanar s"it '- ,r't'c'ls "se b5 t!e Internet Intranet e*tranet an s'+e 't!er

net&'r(s$

a. #63$I3

b. 3rotocol

c. 8pen system

d. Internet work processor

B$= are net&'r(s t!at c'nnect ,e',le &it!in a c'+,an5 t' eac! 't!er an t' t!e c'+,an5 net&'r($

a. Internets

b. Intranets

c. Extranets

d. 6ompunets

B$>$ #he F'!ns'n C'+,an5 is see(ing t' e*,an its b"siness 'nt' t!e Gin-'r+ati'n

!ig!&a5 +ae ,'ssible b5 recent avances in tec!n'l'g5$ T' ' t!is t!e F'!ns'n

C'+,an5 &'"l +'st li(el5 c!''se t!e:

a. Internet. b. Intranet.

c. Extranet.

d. 6ompunet.

L.0@. All of the following would be considered to be specific forces that underlie the new

Internet age EC6E3#:

a. digitali'ation and connecti"ity.

b. the explosion of the Internet.

c. customi'ation and customeri'ation.

d. increasing affluence and income in the United 2tates.

Answer Keys:

%$ ?a@ 2$ ?b@ $ ?c@ 8$ ?b@ ;$ ?c@ 6$ ?c@ $ ?a@ %$ ?@

itbm networking architectire.doc

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