1aditya report

8/12/2019 1aditya Report

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1. INTRODUCTION TO NETWORKING

Definition:-

A network is a system that transmits any combination of voice, video and/or data betweenusers. A network can be defined by its geographical dimensions and by which the users

PC access it.

A network consists of a:

he network operating system (!indows "/#$$$

%

/&p' on the users PC(client' and server.

he ca!esconnecting all network devices (users PC, server, peripherals, etc.'.

All supporting network components(hubs, routers and switches, etc.'.

Comp"ter Network means an interconnecte# co!!ection o$ a"tonomo"s comp"ters.

Re%"irement o$ Networking

Reso"rce s&aring) o make all programs, e*uipment, and especially data available to

anyone on the network without regard to the physical location of the resource and theuser.

'ig& re!iai!ity) As all files could be replicated on two or three machines, so if one of

them is unavailable (due to hardware failure', the other copies could be used.

ca!ai!ity) +t is the ability to increase system performance gradually as the workload

grows ust by adding more processors.

Summer Training Report On Computer Networking


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A computer network can provide a powerful comm"nication me#i"m along widelyseparated employees.

he use of networks to enhance human)to)human communication will probably prove

more important than technical goals such as improved reliability.

hese are the re*uirement with respect to companies but computer networking is re*uired

even in the normal day to day life as we have to access the internet to get information

about what all new happening in the world, to have communication with people stayingfar away using the e mail service.

hese are the reasons that forced the inventories to invent the networking devices, models

and protocols etc.

And the birth of "etworking took place in - when for the first time 0amuel %orse

send the first telegraph message.



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2. Types of Network

)*N ()OC*) *RE* NETWORK+

hese are privately owned networks within a single building or campus of up to a few a

kilometers in si1e.

2A"s are distinguished from other networks by three characteristics:-' heir si1e.

#' heir transmission technology.

3' heir topology.

2A"s are restricted in si1e, which means that the worst)case transmission time isbounded and known in advance.

2A"s often use a transmission technology consisting of a single cable to which all the

machines are attached.

2A"s run at speeds of -$ to -$$ %bps, have low delays, and make very few errors.

)*N ETU,

IEEEhas produced several standards for 2A"s. hese standards collectively known as

IEEE -/ .

+444$#.3 (4thernet', +444$#. (oken 5us', +444$#.6 (oken 7ing'



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hree types of approaches are used to connect !A"s:

-' Circuit switching, which provides a fi8ed connection (at least for the duration of a call

or session', so that each packet takes the same path. 48amples of this approach include+0;", 0witched 6


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OI NETWORK ODE)

he >0+ model describes how information makes its way from application programs

through a network medium to another application program in other computer. +t divides

one big problem in to seven smaller problems . 4ach problem is addressed by one of theseven layers of the >0+ model.



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3"nctions o$ Network )ayers in 2rie$4

*,,)IC*TION )*5ER

@sed for applications specifically written to run over the network Allows access to network services that support applications

;irectly represents the services that directly support user applications

=andles network access, flow control and error recovery

48ample apps are file transfer, e)mail, "et 5+>0)based applications

,REENT*TION )*5ER

ranslates from application to network format and vice)versa

All different formats from all sources are made into a common uniform format

that the rest of the >0+ model can understand

7esponsible for protocol conversion, character conversion, data encryption /

decryption, e8panding graphics commands, data compression

0ets standards for different systems to provide seamless communication from

multiple protocol stacks

"ot always implemented in a network protocol

EION )*5ER

4stablishes, maintains and ends sessions across the network

7esponsible for name recognition (identification' so only the designated parties

can participate in the session

Provides synchroni1ation services by planning check points in the data stream B

if session fails, only data after the most recent checkpoint need be transmitted

%anages who can transmit data at a certain time and for how long

48amples are interactive login and file transfer connections, the session would

connect and re)connect if there was an interruption recogni1e names in sessionsand register names in history

TR*N,ORT )*5ER



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Additional connection below the session layer

%anages the flow control of data between parties across the network

;ivides streams of data into chunks or packets the transport layer of the receiving

computer reassembles the message from packets

rain is a good analogy B the data is divided into identical units

Provides error)checking to guarantee error)free data delivery, with on losses or

duplications

Provides acknowledgment of successful transmissions re*uests retransmission if

some packets dont arrive error)free

Provides flow control and error)handling

CP, A7P, 7A7P

NETWORK )*5ER

ranslates logical network address and names to their physical address (e.g.

computer name B %AC address'

7esponsible for addressing and determining routes for sending

%anaging network problems such as packet switching, data congestion and

routing

+f router cant send data frame as large as the source computer sends, the network

layer compensates by breaking the data into smaller units. At the receiving end,

the network layer reassembles the data

hink of this layer stamping the addresses on each train car

I, A7P 7A7P, +C%P 7+P >09P



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D*T* )INK )*5ER

urns packets into raw bits -$$-$- and at the receiving end turns bits into

packets.

=andles data frames between the "etwork and Physical layers

he receiving end packages raw data from the Physical layer into data frames for

delivery to the "etwork layer

7esponsible for error)free transfer of frames to other computer via the Physical

2ayer

his layer defines the methods used to transmit and receive data on the network.

+t consists of the wiring, the devices use to connect the "+C to the wiring, the

signaling involved to transmit / receive data and the ability to detect signaling

errors on the network media

)ogica! )ink Contro!

4rror correction and flow control

%anages link control and defines 0APs

,'5IC*) )*5ER

ransmits raw bit stream over physical cable

;efines cables, cards, and physical aspects

;efines "+C attachments to hardware, how cable is attached to "+C

;efines techni*ues to transfer bit stream to cable



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C!ass 2) Class 5 is used for medium)si1ed networks. A good e8ample is a large college

campus. +P addresses with a first octet from -# to-G- are part of this class. Class 5

addresses also include the second octet as part of the "et identifier. he other two octetsare used to identify each host.

"et =ost or "ode

-6.# 63.-G

C!ass C) Class C addresses are commonly used for small to mid)si1e business. +Paddresses with a first octet from-G# to ##3 are part of this class. Class C addresses also

include the second and third octets as part of "et identifier. he last octet is used to

identify each host.

"et =ost or "ode-G


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5asically it is a process of subdividing networks into smaller subnets.

+n case we have #)3 small networks but we cant buy +P address for each and every

network. 0o here we use the basic concept of 0@5"4+"H i.e. using one public +Paddress we will give them +P address and make them independent networks. 9or this we

take some bits of host address and use them for network address so we have different

independent networks

Address 9ormat when 0ub netting +s @sed (class A,5,C resp.':

#)8 8

"etwork 0ubnet =ost

-< -


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Co!!ision Domain8+t is the group of PCs in which collision will occur when two PC willtransmit data simultaneously.

2roa#cast Domain8+t is the group of PCs those will receive same broadcast message.

C*9CD (Carrier ense "!tip!e *ccess9 Co!!ision Detection+8 +n this protocolwhen a PC wants to transmit any packet it sense the carrier i.e. the path ,if no other PC is

using the carrier then only it sends. +f two PCs start sending data simultaneously collision

will occur. 5oth PCs will wait for some random time and then initiate the same process.

*C(%edia Access Control' . he +444 $#.3 (4thernet' and $#.6

(oken 7ing' are the %AC sub layers of these two 2A" data)link protocols.

2"rne#8in a##ress4 he % or 44P7>% on the 2A" card and begins with

a 3)byte organi1ationally uni*ue identifier (>@+' assigned by

the +444.

)oca!!y a#ministere# a##ress4hrough configuration, an address that is used instead of

the burned)in address.

Unicast a##ress49ancy term for a %AC that represents a single 2A"

+nterface.

4 NETWORKING DEVICES



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"etworking devices do various kind of obs like transferring the data to signals, providing

connectivity to different network devices, transferring the data in form of packets or

frames form one device to other. hese are the central connections for all the networke*uipments and handle a data type known as frame or packet. Actually frames/ packet

contain data and the destination address of where it is going. !hen a frame is received, it

is amplified and then transmitted on to port of destination PC. 5ut different networkingcomponents do this ob in diff form at diff layers.

NETWORK INTER3*CE C*RD

A "etwork +nterface Card ("+C' is a circuit board that plugs into both clients and servers

and controls the e8change of data between them (A specific software IdriverJ must beinstalled depending on the make of the "+C. A physical transmission medium, such as

twisted pair or coa8ial cable interconnects all network interface cards to network hubs or

switches. 4thernet and oken 7ing are common network interface cards. odays cardssupports -$base and -$$base with automatic recognition.

'U2

!hen the need for interconnecting more then # devices together then a device known as

hub comes to picture. 5asically hub is a layer one device. i.e. it operates on the physical

layer of the >0+ model. +t is designed to do broadcasting i.e when it gets any frame itbroadcasts it to every port irrespective that whether it is destined for that port or not. =ub

has no way of distinguishing which port a frame should be sent. 5roadcasting results inlot of traffic on the network which lead to poor network response. +f two PCsimultaneously transmit there data packets and both are connected to a =@5, then

collision will occur, so we can say, it creates a single collision domain. >n the other hand

all PCs connected to a hub will get a same message so a single broadcast domain will be

created.

A -$$/-$$$ %bps hub must share its bandwidth with each and every one of its ports. 0o

when only one PC is broadcasting, it will have access to the ma8 available bandwidth. +f,however, multiple PCs are broadcasting, then that bandwidth will need to be divided



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between all of these systems, which will degrade the performance. hey are usually =alf)

;uple8 in nature.

WITC'=ubs are capable of oining more than two PC but having some demerits like if two PC

would want to communicate at a time then there would be a collision and the both PCwould have to send the data once again. his shortcoming of =ub is overcame by

0witches. 0witches are intelligent devices which work on the 2ayer# of the >0+ model.

5asically a switch keeps a record of %AC addresses of all the devices connected to it.@sing this information, it builds a %AC address table. 0o when a frame is received, it

knows e8actly which port to send it to, which increases the network response time.

5asic !orking Principle of 0witch.

-. At the time of initiali1ing the switch the %AC address table is yet to be built up.!hen a frame is send by some of the PC, it recognises the source %AC address

and update the %AC address table.

#. +f the destination is available in the %AC table then forward to the corresponding

PC.3. +f the destination %AC address is not present in the table then forwards in all the

port available e8pect the incoming one. he designated PC will respond for the

data and it will send the acknowledge for the data received. his acknowledgeddata will be e8amined by the switch and the %AC address table would be up

dated accordingly.

+f two PC simultaneously transmit there data packets and both are connected to a0!+C=, then collision will not occur, so we can say, it creates a multiple collision

domain.

he switch supports broadcast. =ence we can call switches create single broadcast

domain and multiple collision domains.

A -$$/-$$$%bps switch will allocate a full -$$/-$$$ %bps to each of its ports. 0o

regardless of the no of PCs transmitting user will always have access to ma8 amt ofbandwidth. hey are usually 9ull);uple8 in nature.



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ROUTER

0witch and the =ub can only interconnect devices in a single 2A". 9or interconnecting

two 2A" or two or more different networks anther device known as router is used. +ts

main ob is to route ( sends ' packets to other networks and to do the routing( establishing paths between networks ' it uses the +P address. A router is typically

connected to at least two networks, commonly two 2A"s or !A"s or a 2A" and its+0Ps network. 7outers are located at gateways, the places where two or more networks

connect. 7outers to determine the best path for forwarding the packet are using

forwarding tables.

+t is a layer 3 device i.e it operates at network layer of >0+ model. he working principle

of the router is totally different from a switch. 7outer makes a table known as ro"ting

ta!e: which contains all the +P address in the network, the information for +P address

router obtains directly ( all configured +P address on it ' or indirectly ( from neighbour

routers '. !hen a packet is received it compares the destination +P address of the packetwith the available +P addresses in its 7outing table. +f the +P address is not available in

the routing table then it simply discard the packet instead of flooding in all the ports like

a switch.(;etailed +nformation about router in chap '



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Comparison etween '": 2ri#ge: witc& ; Ro"ter

Feature Hu !r"#$e Sw"t%& Router

Nu'er ofroa#%ast#o'a"s Segment 1 1

1 perrouterinterface

Nu'er of%o"s"o#o'a"s 1

1 perbridgeport

1 per switchport

1 perrouterinterface

Forwar#s *ANroa#%asts+ 1 Yes Yes No

Forwar#s *AN'ut"%asts N/A Yes

Yes; can be

optimized forlessforwarding No

OSI ayer use#w&e 'ak"$forwar#"$#e%"s"o N/A Laer 2 Laer 2 Laer !

Iterapro%ess"$

,ar"ats N/A

Store"and"

forward

Store"and"forward# cut"through#$ragment$re

e

Store"and"

forwardFra'e-pa%ketfra$'etat"oaowe#+ N/A No No Yes

.ut"pe%o%urrete/ua0%ost pat&sto sa'e#est"at"oaowe#+ N/A No No Yes



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< ROUTER

ROUTER INTERN*) CO,ONENT

2ike a computer, a router has a CP@ that varies in performance and capabilities

depending upon router platform. +t has typically types of memory in it.:

RO) +t is used to store the routers bootstrap startup program, operating system

software, and power)on diagnostic tests programs. !e can also upgrade our 7>%

3)*' EOR5) +t holds operating systems image(s'. 9lash memory is erasable,reprogrammable 7>%. >ur +>0 software is present in this memory and we can upgrade

it also. 9lash content is retained even when we switch off or restart the router.

R*) +t is used to store operational information such as routing tables, routers running

configuration file. 7A% also provides caching and packet buffering capabilities. +ts

content is lost when we switch off or restart the router. !hen we configure the router atthat time actually we are writing in 7A%.

N=R*) +t is used to store the routers startup configuration file. +t does not lose datawhen power is switched off. 0o the contents of startup configuration files are maintained

even when we switch off or restart the router.



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ROUTER> NETWORK INTER3*CE

Et&ernet or Token Ring inter$aceare configured to allow connection to a 2A".

ync&rono"s seria! inter$acesare configured to allow connections to !A"s.

IDN 2RI inter$acesare configured to allow connection to an +0;" !A".

All cisco routers have a conso!e portthat provides an 4+A/+A)#3# asynchronous serial

connection. Console port can be connected to computers serial connection to gainterminal access to router.

%ost routers also have an a"7i!iary port that is very similar to console port but, istypically used for modem connection for remote router management.

CON3IGURING T'E ROUTER



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here are three methods for configuring the router:

-' hrough console port:) he console port is used for configuring a router locallywith the help of a PC or a 2aptop. he console port of the router is connected to

the serial i.e C>% port of the router. he detailed configuration is given in thesection.

#' hrough the A@& port:) he au8 ( au8iliary ' port is accessed from a modem

located faraway from a router through the P0" ( Public 0witched elephone

"etwork ' and the configuration is done.

3' hrough elnet:) 2ine vty ( virtual terminal ' $ to are used for the configuringthe router by telnet.

Con$ig"ring Ro"ter t&ro"g& Conso!e port

!e use =ypererminal Program to open a conso!e session and log into the router locally.

his console connection allows to connect to and to communicate with router without

having to connect to the network to which it belongs. "ow, the PC becomes the consolethat allows to enter commands and communicate directly with the router. o set up a

console session, we use the workstations !indows =ypererminal (terminal emulation'

program. "ow first of all we configure the C>% port settings, then log into the router to

interact with the +>0 command line interface (C2+'. hese are the com port settings:

G


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Connect to the device of the PC

C>% - 0etting



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'yper termina! creen



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*$ter connecting t&e ro"ter t&at wi!! oot an# a$ter ooting t&e $o!!owing

proce#"res wi!! e a#opte#.

Ro"ter? ena!e

"ow automatically prompt asking for password will appear on the screen like this:

,asswor#4

"ow write password over here. his is done to secure access to router. After this

Ro"ter@

will appear on the screen this shows that we are in privileged mode and now we try to

enter in configuration mode.

Ro"ter@ con$ig"re termina!

his is done to enter configuration mode."ow starts the configuration of router

"ow we will assign +P address to each and very interface connected to router. 0ubnet

mask should be given with a proper care. 9ollowing steps are to be followed:

9or configuring Et&ernet inter$ace:

Ro"ter@config terminal

Ro"ter (con$ig+ @ interface ethernet $

Ro"ter (con$ig8i$+ @ip address ##3..-6-.- #66.#66.#66.$

Ro"ter (con$ig8i$+ @no shutdown

Ro"ter (con$ig8i$+@e8it

9or configuring seria! inter$ace:

Ro"ter (con$ig+@interface serial $

Ro"ter (con$ig8i$+@ip address #$.#$.D.- #66.#66.#66.$

Ro"ter (con$ig8i$+@no shutdown

Ro"ter (con$ig8i$+@e8it

Ro"ter (con$ig+@interface serial -

Ro"ter (con$ig8i$+@ip address -GG.


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ROUTING ,ROTOCO)

ROUTING IN3OR*TION ,ROTOCO) (RI,+

7+P is a dynamic, distance vector routing protocol. 7+P uses @;P port 6#$ for routeupdates. 7+P calculates the best route based on hop count. his makes 7+P very fast toconverge

7+P sends full table updates at regular intervals specified by the route)update timer (3$

seconds is the default'. his means that a 7+P router summari1es all routes it knows along

classful boundaries and sends the summary information to all other 7+P routing devices.7+P updates can contain up to #6 messages.

7+P +%470

+%47 ;49A@2 C>"7>20

"p#ate3$ sec. +nterval between route update advertisementstimeo"t -$ sec. +nterval a route should stay MliveM in the routing table. his

counter is reset every time the router hears an update for this route.

3!"s& #$ sec. =ow long to wait from the time the route was received todelete a route (


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router(config)router'N network -G#.-


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I, *CCE )IT

+P access lists cause a router to discard some packets based on criteria defined by thenetwork engineer. he goal of these filters is to prevent unwanted traffic in the network

?whether to prevent hackers from penetrating the network, or ust to prevent employeesfrom using systemsthat they should not be using.

Key features of access lists:

Packets can be filtered as they enter an interface, before the routing decision. Packets can be filtered before they e8it an interface, after the routing decision.

Deny is the term used in Cisco +>0 software to imply that the packet will be filtered.

Permit is the term used in Cisco +>0 software to imply that the packet will not befiltered.

he filtering logic is configured in the access list.

At the end of every access list is an implied Ideny all trafficJ statement. herefore, if apacket does not match any of your access list statements, it is blocked.

Access lists have two maor steps in their logic: matching and action. %atching logice8amines each packet and determines whether it matches the

access8!ist statement. As soon as an access8!ist statement is matched, there are two

actions to choose from: deny and permit. ;eny means to discard the packet, and permit

implies that the packet should continue on its way.



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N*T CO*ND

he nat ("etwork Address ranslation' command translates a set of +P addresses to

another set of +P addresses.

0Q"A&: nat ( if_name) nat_id local_ip [netmask](if_name) he internal network interface name.

nat_id he +; number to match with the global address pool.local_ip he +P address that is translated. his is usually the inside network+P address.

netmask"etwork mask for the local +P address.

here are two types of "Aing:-' 0tatic: 9or e8. here is a google server and we dont want to make its +P address

public so we change its +P address using nat command in firewall and now user

will logon to this new +P . his results in more security as every time it has to passthrough firewall.

#' ;ynamic: +f there are lots of PCs in a network and all want to access the internet

, it is not easy that every PC is being provided with independent public +P so atfirewall level we change every PCs pvt +p with public +P.

48amples:nat (inside' - -$.-$.-$.$ #66.#66.#66.$

nat (inside' - -D#.-


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WITC'ING ER=ICE

@nlike bridges, which use software to create R manage a filter table,switches useapplication specific integrated circuit to build R maintain filter table.5ut its still okay tothink of a layer # switch as a multiport bridges because their basic reason for being is

same: to break up collision domain.

2ayer # switching and bridges are faster than routers because they dont take up timelooking at the "etwork layer header information. +nstead, they look at frames hardware

address before deciding to either forward, flood or drop the frame.

0witches create private, dedicated collision domain and provide independent b.w. on eachport, unlike hub. 9ig. shows five host connected to a switch) all running -$ mbps half

duple8 to server.

2ayer # switching provide the following:

=ardware based switching (A0+C'

!ire speed2ow latency

2ow cost

!hat makes layer# switching so efficient is that no modification to the data packetstakes place. he device only reads the frame encapsulating the packets which makes the

switching process considerably and less error prone than the routing process.

Plus layer # switching increase the b.w. for each user because again each connection into

the switch is its own collision domain. his feature makes it possible for u to connectmultiple devices to each interface.



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)imitations o$ )ayer / witc&ing

2ayer # switches have the same limitations as bridge networks. 0ince we commonly stick

layer # switching into the same category as bridged networks, we alsotend to think it has the same hang)ups and issues that bridged networks do. Keep in mind

that bridges are good and helpful things if we design the network correctly, users spend

$ percent of their time on their local segment. 5ridged networks break up collisiondomains, but the network is still one large broadcast domain. 0imilarly, layer # switches

(bridges' cannot break up broadcast domains, which can cause performance issues and

limit the si1e of your network. 5roadcasts and multicasts, along with the slow

convergence of spanning tree, can cause maor problems as the network grows. 5ecauseof these problems, layer # switches cannot completely replace routers in the internetwork.

keeping t&eir $eat"res as

well as their limitations in mind. And to design well with bridges, these are the two most

impor)tant considerations:

!e absolutely must break up the collision domains correctly.

he right way to create a functional bridged network is to make sure that its users

spend

5ridged networks break up collision domains, but remember, that network is still onelarge broadcast domain. "either layer # switches nor bridges break up broadcast domains

by default?something that not only limits your networkMs si1e and growth potential, but

also can reduce its overall performance.5roadcasts and multicasts, along with the slow convergence time of spanning trees, can

give

you some maor grief as your network grows. hese are the big reasons layer # switchesand

bridges cannot completely replace routers (layer 3 devices' in the internetwork.

http://cisco.harshil.in/routing-and-switching/r-and-s/limitations-of-layer-2-switching/http://cisco.harshil.in/routing-and-switching/r-and-s/limitations-of-layer-2-switching/


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W)*N (WIRE)E )*N+

+n a traditional 2A" each computer physically connects to the network via wires and a

network port. A !ireless 2ocal Area "etwork (!2A"' is a network that provides thesame services but without the need for physical connections between the computers and

the network. !ireless 2A"s offer many advantages over traditional wired networks, such

as mobility, fle8ibility, scalability and speed, simplicity and reduced cost of installation.A !2A" typically uses radio waves, which allow network PC cards plugged into a

PC/laptop to connect to a traditional 4thernet 2A".

+444 developed the $#.-- standards to provide wireless networking technology like thewired 4thernet.

T*ND*RD

+444 developed the $#.-- standards to provide wireless networking technology. !ith

time)to)time development in the field of technology three standards has been finali1ed.

$#.--(a', $#.--(b', $#.--(g'

$#.--(b' $#.--(a' $#.--(g'

%a8. bit rate/7awnet

--%b/s6.6%b/s

6 %b/s##)#< %b/s

6 %b/s-D)## %b/s

9re*uency 5and #. H=E 6 H=E #. H=E

7ange S %a8. rate 6D m -#m -Gm

@nit Cost -$$T -#$T --$T

Coverage Cost -$$T #$$$T 6$$T

"o. of channels 3

+444 $#.--a standard is the most widely adopted one because it operates at licensed 6

H=E band while other are unlicensed and also it provides ma8. nof channels and ma8. bit

rate than any other standards.

TO,O)OGIE

here are two topologies on which !2A" works:-' +nfrastructure "etwork

#' Ad hoc "etwork



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IN3R*TRUCTURE NETWORK

+t is useful for providing wireless coverage of building or campus areas. his is atopology used when there are many access points in a single location. 5y deploying

multiple Access Points (APs' with overlapping coverage areas, organi1ations can

achieve broad network coverage. . A laptop or other mobile device may move fromAP to AP while maintaining access to the resources of the 2A". 4ach client is

e*uipped with wireless network interface card ("+C' that consists of the radio

transceiver and the logic to interact with the client machine and software. !hile the

AP is essentially a radio transceiver on one side and the wired backbone on the other.



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A;=>C "4!>7K

his topology is used when we have to interconnect mobile devices that are in the same

area (e.g., in the same room'. +n this architecture, client stations are grouped into a singlegeographic area and can be +nternet)worked without access to the wired 2A"

(infrastructure network'. he ad hoc configuration is similar to a peer)to)peer office

network in which no node is re*uired to function as a server. +n ad hoc there is no need ofany AP as all devices are wirelessly connected to each other.



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1aditya report

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