wlanbasics-

7/24/2019 wlanbasics-

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WLAN basics

The Must Knows

Presented by Keith Charles.

Corporate Trainer.

Lesson One


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What is a WLAN?

A WLAN is a network where clients connect to the network using

the atmosphere (RF)as the transmission media.


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Deine transmission media.

!n simple terms" the transmission media is the path along which

data tra#els. $nlike in a wired network where we use wire or

%bounded& transmission media" the WLAN client recei#es and

transmits data across the atmosphere.


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'he client.

imilar to wired en#ironments" the client is a recei#er o ser#ices.A WLAN client is sometimes described as a mobile client.

When ou plug in our internet cable or hardwire a *+ or internetaccess ou are creating a wired interace. 'he interace must bepresent in our client or wireless connecti#it.e.g. centrino or aradio card (antenna).

,ost users are aware o Linkss- Netgear- Apple etc.


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WLAN transmissions.

'oda most laptops are sold with wireless capabilit" meaningthat the are euipped with the interace" a radio" that allowsthem to send and recei#e data through the air.

/uestion0 how do ou think our laptop inds our neighbor1snetwork as soon as it is powered up?

Answer0 'he scanor search. ,ore on this later.


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WLAN designs.

'wo #er basic designs are a#ailable02

3. peer to peer 4R adhoc.!n this design also called an

independent basic ser#ice set (!5)" there is no central pro#ider

o network ser#ices i.e. an access point or A*.


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WLAN Designs

6. 'he inrastructure network in which there is at least 3 accesspoint (A*) which acts like a ser#er in a wired network.

'hereore in an inrastructure design ou ha#e an access pointwith at least one client. !n the case where there is 3 A* it is calleda 5asic er#ice et or 5.

IBSS

EBSS


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WLAN Design

7. !n an inrastructure design where there is more than one A*

ou now ha#e an 89tended 5asic er#ice et.

8ach A* has a co#erage area or cell or RF ootprint. 'he

reception degrades as ou mo#e out o the cell. 'his is normallshown with bars at the right bottom o our *+.

'hink :eri;on" the ad %can ou hear me now?&


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'he Access *oint

An access point is a powerul little de#ice. Remember it is

connected to the wired network. 'hat means it has to take data

rom the wired side and %con#ert& them to something

transmittable on the air.

At this time let us remember the term %rame&.

An access point recei#es rames rom the wired side and spits

out rames on the wireless side.

!888 >>>>>>>!888 >>>>>>>>>WLAN rames.


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/uestion.

! ! ha#e one A* ! will thereore ha#e one cell or ootprint. 3.ow

man ootprints@cells would ! ha#e with 6 A*s ?

6. ! ! ha#e two A*s and ! want to be able to ha#e a non2

interrupted connection when mo#ing rom cell to cell" what do outhink ! must do?

Note cell overlap


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canning.

A client inds a network using a scan. A scan can be acti#e or passi#e.

'hink o the times when ou heard about a search or a black bo9 ater aplane crash. 'hat bo9 sends out a beacon that can be picked up b thesearcher.

Note02 beacons are also sent rom client to client in a design with no A*. +an ou remember the name o that design?

An access point sends out a similar beacon" more or less e9claiming %!am here&. !n an acti#e scan" the client sends out a probe looking or anA*.

'he client sends a %probe reuest& and the A* ma or ma not send a%probe response&.


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canning

A passi#e scan is not reall directed" i ou will. 'he client ust

%listens& or beacons on e#er channel.

Note0 these e9planations are #er basic. 'here is a lot more but

this is enough or building an understanding.


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Finding An A*.

! ou ha#e e#er set up a wireless network ou will recall setting

up an !D. 4r i ou ha#e ne#er" ou ma recall the name o

our neighbor1s wireless. 'hat is the !D or er#ice et

!dentiier.

!1#e seen some unn !Ds in m searches. 'his is basicall a

network name and is helpul or WLAN management. ome A*s

allow us to hide or not broadcast our !Ds.

Note0 this pro#ides #er little securit" since the !D can beound elsewhere. ,ore on that later.


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Notice !Ds Bsignal strength


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'erminolog to remember

+lient

Access point

!nrastructure mode

*eer to peer

!5

89tended 5 canning

*assi#e scan

Acti#e scan

!D

5eacon

Frame


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Looking AheadC.Lesson 'wo

Associate

Reassociate

Disassociate

Authenticate

Deauthenticate *robe

Data rate

,odulation

8ncoding


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!no.

I am very much interested in continuing this once weekly lesson

on wireless technology. If you are in favor of this please send

your vote of support to

[email protected]

Note: I propose to cover all topics. It will get tougher as we move

along so I intend to develop a few podcasts and video tutorials.

Questions and suggestions are welcomed!
mailto:[email protected]:[email protected]

Date post:	20-Feb-2018
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