Expl sw chapter_07_wireless rev.01

CCNA3-1 Chapter 7-1
Basic Wireless Concepts and ConfigurationBasic Wireless Concepts and Configuration
The Wireless LANThe Wireless LAN

CCNA3-2 Chapter 7-1
• Perkembang Networking saat ini sudah dapat mendukung aktifitasPerkembang Networking saat ini sudah dapat mendukung aktifitas
kita secara mobile/bergerak.kita secara mobile/bergerak.
• Sehingga produktifitas kita saat iniSehingga produktifitas kita saat ini no longer restrictedno longer restricted lokasilokasi
kerja yang tetap ataupun dibatasi oleh waktu.kerja yang tetap ataupun dibatasi oleh waktu.
• Kita saat ini membutuhkan suatu network yang selaluKita saat ini membutuhkan suatu network yang selalu
terkoneksi untuk dapat melakukan komunikasi dan aktifitasterkoneksi untuk dapat melakukan komunikasi dan aktifitas
kita setiap saat dan setiap tempat atau dimana saja.kita setiap saat dan setiap tempat atau dimana saja.
• Dengan networking yang dapat mendukung aktifitas kitaDengan networking yang dapat mendukung aktifitas kita
secara mobile, maka saat ini kita dapat melakukan pekerjaansecara mobile, maka saat ini kita dapat melakukan pekerjaan
seperti checkseperti check e-mail, voice mail, and the status of productse-mail, voice mail, and the status of products
menggunakan personal digital assistants (PDAs) ataumenggunakan personal digital assistants (PDAs) atau
handphone maupun pc tablet dari lokasi diluar kantor.handphone maupun pc tablet dari lokasi diluar kantor.
• Access InternetAccess Internet dirumah-rumah saat ini sudah beralih daridirumah-rumah saat ini sudah beralih dari
modem dial-up lama ke dedicated DSL atau cable servicemodem dial-up lama ke dedicated DSL atau cable service
maupun handphone.maupun handphone.
Why Use Wireless?Why Use Wireless?

CCNA3-3 Chapter 7-1
• Pada awalnya networks komunikasi terbatas hanya padaPada awalnya networks komunikasi terbatas hanya pada
pertukaran informasi character based.pertukaran informasi character based.
• Communications antar computers (cross) tidak mudahCommunications antar computers (cross) tidak mudah
dilakukan dan memerlukan host/pc untuk keperluandilakukan dan memerlukan host/pc untuk keperluan
komunikasi transfer data sederhana.komunikasi transfer data sederhana.

CCNA3-4 Chapter 7-1
• Saat ini networks dapat membawa berbagai jenis tipe dataSaat ini networks dapat membawa berbagai jenis tipe data
information melalui banyak jenis device secarainformation melalui banyak jenis device secara
SSIMULTANEOUSLY/bersamaanIMULTANEOUSLY/bersamaan..
• Kita mendapatkan response secara langsung dari lawanKita mendapatkan response secara langsung dari lawan
komunikasi kita dimanapun kita berada.komunikasi kita dimanapun kita berada.
Silver and Diamond
Cell Phone $1.3Million
Wind Energy Cell Phone Charger

CCNA3-5 Chapter 7-1
• Selain flexibility yang disediakan teknologi WLANs,Selain flexibility yang disediakan teknologi WLANs,
keuntungan lainnya adalahkeuntungan lainnya adalah reduced costsreduced costs..
• Moving persons within a building with a wirelessMoving persons within a building with a wireless
infrastructure.infrastructure.
• Moving into a new building with no wired infrastructure.Moving into a new building with no wired infrastructure.
Wired NetworkWired Network Wireless NetworkWireless Network
ComponentComponent QtyQty CostCost TotalTotal QtyQty CostCost TotalTotal
Switches,Switches,
cabinets, etc.cabinets, etc.
167167 3,3503,350 559,450559,450 2525 4,4044,404 110,100110,100
CablingCabling 7,5007,500 4545 337,500337,500 430430 7575 61,92061,920
Network AdaptersNetwork Adapters 2,5002,500 5757 142,500142,500 2,5002,500 7777 192,500192,500
Wireless AccessWireless Access
PointsPoints
250250 1,0341,034 258,500258,500
POE AdaptersPOE Adapters 4040 6767 2,6802,680
TotalTotal 1,039,4501,039,450 364,520364,520
Note: Values are estimates and do not reflect actual pricing.Note: Values are estimates and do not reflect actual pricing.Note: Values are estimates and do not reflect actual pricing.Note: Values are estimates and do not reflect actual pricing.

CCNA3-6 Chapter 7-1
• Kebanyakan network dalam suatu perusahaan menggunakan Switch-Kebanyakan network dalam suatu perusahaan menggunakan Switch-
Based LANs untuk operasional sehari-hari didalam gedung kantor.Based LANs untuk operasional sehari-hari didalam gedung kantor.
• Namun saat ini pekerja banyak melakukan pekerjaan secara mobile danNamun saat ini pekerja banyak melakukan pekerjaan secara mobile dan
ingin dapat mengakses ke network perusahaan untuk melakukan aktifitasingin dapat mengakses ke network perusahaan untuk melakukan aktifitas
kerja yang tidak hanya dapat dilakukan dari meja kerjanya saja.kerja yang tidak hanya dapat dilakukan dari meja kerjanya saja.
Wireless LANsWireless LANs

CCNA3-7 Chapter 7-1
• Wireless LAN dapat menjadi pilihan yang efektif, sebagaiWireless LAN dapat menjadi pilihan yang efektif, sebagai
perpanjangan/yang menghubungkan kita ke Ethernet LAN.perpanjangan/yang menghubungkan kita ke Ethernet LAN.
Wireless LANsWireless LANs

CCNA3-8 Chapter 7-1
Comparing a WLAN to a LANComparing a WLAN to a LAN
Network Architecture StandardsNetwork Architecture StandardsNetwork Architecture StandardsNetwork Architecture Standards
Physical MediaPhysical MediaPhysical MediaPhysical Media

CCNA3-9 Chapter 7-1
Wireless Access Points (AP)Wireless Access Points (AP)
instead of a switch.instead of a switch.
Wireless Access Points (AP)Wireless Access Points (AP)
instead of a switch.instead of a switch.
PrivacyPrivacy
IssuesIssues
PrivacyPrivacy
IssuesIssues

CCNA3-10 Chapter 7-1
• CSMA/CD (Collision Detection)
• Proses awal, perangkat memantau media untuk keberadaan sinyal
data.
• Jika tidak ada sinyal data, atau media dalam kondisi bebas, maka
perangkat dapat melakukan transmisi data.
• Tetapi jika ada sinyal yang terdeteksi, ini menunjukkan perangkat lain
sedang melakukan transmisi data dan semua perangkat lain harus
menghentikan pengiriman dan akan mencoba lagi diwaktu berikutnya.
• Metode ini digunakan oleh jaringan Ethernet 802.3
• CSMA/CA (Collision Avoidance)
• Proses awal, melakukan pemeriksaan perangkat media, dan
keberadaan dari sinyal data.
• Kemudian perangkat mengirim pemberitahuan kepada semua node
akan melakukan pengiriman data, permintaan untuk melakukan
pengiriman, dengan maksud untuk menggunakan media penghantar
• Setelah itu perangkat kemudian melakukan pengiriman data
• Metode ini digunakan oleh jaringan Nirkabel/Wireless 802.11

• Additional components and protocolsAdditional components and protocols yang digunakan pada 802.11yang digunakan pada 802.11
wireless connections sebagai extend dari 802.3 Ethernet LAN.wireless connections sebagai extend dari 802.3 Ethernet LAN.
Wireless LAN ComponentsWireless LAN Components
Point (AP)Point (AP)
Point (AP)Point (AP)

• 802.11 wireless LAN802.11 wireless LAN::
• IEEE standard menentukan radio frequency (RF) untukIEEE standard menentukan radio frequency (RF) untuk
kebutuhan unlicensed Industrial, Scientific, and Medicalkebutuhan unlicensed Industrial, Scientific, and Medical
(ISM)(ISM) berdasarkan frequency bands yang digunakan olehberdasarkan frequency bands yang digunakan oleh
Physical layerPhysical layer dandan MAC sub-layerMAC sub-layer dari wireless links.dari wireless links.
• Typically frequency bands ini, dipilih berdasarkanTypically frequency bands ini, dipilih berdasarkan
standart daristandart dari data ratedata rate-nya.-nya.
Wireless LAN StandardsWireless LAN Standards
Final ratificationFinal ratification
expected inexpected in
November, 2009November, 2009
Final ratificationFinal ratification
expected inexpected in
November, 2009November, 2009

• Data Rates dipengaruhi oleh teknik modulation yang digunakan:
1. Direct Sequence Spread Spectrum (DSSS):
Juga dikenal sebagai Direct Sequence Code Division Multiple Access
(DS-CDMA), DSSS adalah salah satu jenis dari modulasi spread
spectrum untuk pengiriman data digital kecepatan tinggi melalui radio.
Umumnya peralatan IEEE 802.11b menggunakan DSSS untuk
memancarkan data-nya yang memberikan kecepatan sekitar 11Mbps.
Pada saat dikirim, seluruh data akan digabungkan dengan sebuah data
berurut kecepatan tinggi (yang dikenal sebagai chipping code) yang
akan mendefinisikan perbandingan spreading dari data.
Chipping code akan menolong me-reduce interferensi dan juga
merecover data menjadi data aslinya kembali jika terjadi kerusakan pada
saat dikirim.
• Simpler of the two methods.
• Less expensive to implement.
• 802.11b and 802.11g.

2. Orthogonal Frequency Division Multiplexing (OFDM):2. Orthogonal Frequency Division Multiplexing (OFDM):
Merupakan teknik mudulasi untuk komunikasi wireless broadbandMerupakan teknik mudulasi untuk komunikasi wireless broadband
dimasa yang akan datang, karena OFDM ini tahan melawan frekuensidimasa yang akan datang, karena OFDM ini tahan melawan frekuensi
selective fading dan interferensi narrowband dan efisien menghadapiselective fading dan interferensi narrowband dan efisien menghadapi
multi-path delay spread. Untuk mencapai hal tersebut, OFDM membagimulti-path delay spread. Untuk mencapai hal tersebut, OFDM membagi
aliran data high-rate menjadi aliran rate yang lebih rendah, yangaliran data high-rate menjadi aliran rate yang lebih rendah, yang
kemudian dikirimkan secara bersama pada beberapa sub-carrier.kemudian dikirimkan secara bersama pada beberapa sub-carrier.
Sub-carrier dimodulasikan sendiri dengan menggunakanSub-carrier dimodulasikan sendiri dengan menggunakan Phase ShiftPhase Shift
Keying (PSK) atau Quadrature Amplitude Modulation (QAM).Keying (PSK) atau Quadrature Amplitude Modulation (QAM).
• Data rates lebih cepat dibandingkan dengan DSSS.Data rates lebih cepat dibandingkan dengan DSSS.
• 802.11a, 802.11g, 802.11n.802.11a, 802.11g, 802.11n.

• 802.11a Standard:802.11a Standard:
• OFDMOFDM modulation & menggunakan Frekusensimodulation & menggunakan Frekusensi 5 GHz5 GHz..
• Less likely to experience interferenceLess likely to experience interference than devicesthan devices
that operate in the 2.4 GHz band because there arethat operate in the 2.4 GHz band because there are
fewer consumer devices that use the 5 GHz band.fewer consumer devices that use the 5 GHz band.

• 802.11a Standard:802.11a Standard:
• Disadvantages/kerugianDisadvantages/kerugian menggunakan frekuensi 5GHz.menggunakan frekuensi 5GHz.
• More easily absorbed by walls (obstructions).More easily absorbed by walls (obstructions).
• Jangkauannya lebih pendek dibanding 802.11g.Jangkauannya lebih pendek dibanding 802.11g.
• Dibeberapa negara dilarang digunakanDibeberapa negara dilarang digunakan

• 802.11b and 802.11g Standard:802.11b and 802.11g Standard:
• Both use the 2.4 GHz band.Both use the 2.4 GHz band.
• 802.11b:802.11b:
• Up toUp to 1111 Mb/s usingMb/s using DSSSDSSS..
• 802.11g:802.11g:
• Up toUp to 5454 Mb/s usingMb/s using OFDMOFDM..

• 2.4 GHz band:2.4 GHz band:
• Advantage:Advantage:
• Jangkauan yang lebih baik dibanding band 5GHz karenaJangkauan yang lebih baik dibanding band 5GHz karena
sinyalnya tidak mudah terhalang.sinyalnya tidak mudah terhalang.
• Disadvantage:Disadvantage:
• Banyak perangkat lain menggunakan band ini sehinggaBanyak perangkat lain menggunakan band ini sehingga
sangat rentan terhadap gangguan (microwave oven,sangat rentan terhadap gangguan (microwave oven,
monitor bayi, Bluetooth, telepon cordless).monitor bayi, Bluetooth, telepon cordless).

• 802.11n: (November 2009)802.11n: (November 2009)
• Didesign untuk meningkatkan kecepatan data WLAN dan jangkauanDidesign untuk meningkatkan kecepatan data WLAN dan jangkauan
tanpa memerlukan daya tambahan atau alokasi RF band.tanpa memerlukan daya tambahan atau alokasi RF band.
• MenggunakanMenggunakan multiple radios and antenna at endpointsmultiple radios and antenna at endpoints, dan, dan
masing-masing melakukan broadcasting dengan frequency yangmasing-masing melakukan broadcasting dengan frequency yang
sama untuk membentuk multiple streams.sama untuk membentuk multiple streams.
• Multiple Input / Multiple OutputMultiple Input / Multiple Output (MIMO) and OFDM(MIMO) and OFDM..
• Theoretical maximum of 248 Mb/s.Theoretical maximum of 248 Mb/s.

• Wireless NICs:Wireless NICs:
• The device that makes a client station capable of sendingThe device that makes a client station capable of sending
and receiving RF signals is the wireless NIC.and receiving RF signals is the wireless NIC.
• Like an Ethernet NIC, the wireless NIC, using theLike an Ethernet NIC, the wireless NIC, using the
modulation technique it is configured to use,modulation technique it is configured to use, encodes aencodes a
data stream onto an RF signaldata stream onto an RF signal..
• Wireless NICs are most often associated with mobileWireless NICs are most often associated with mobile
devices, such as laptop computers.devices, such as laptop computers.
Wireless Infrastructure ComponentsWireless Infrastructure Components

• Wireless Access Points:Wireless Access Points:
• An access point is a Layer 2 device that functions like anAn access point is a Layer 2 device that functions like an
802.3 Ethernet hub.802.3 Ethernet hub.
• Connects wireless clients (or stations) to the wired LAN.Connects wireless clients (or stations) to the wired LAN.
• Client devices communicate with the AP – not each other.Client devices communicate with the AP – not each other.
• Converts the TCP/IP data packets from their 802.11Converts the TCP/IP data packets from their 802.11
frame encapsulation to the 802.3 Ethernet frame format.frame encapsulation to the 802.3 Ethernet frame format.
• Clients mustClients must associateassociate with an access point to obtainwith an access point to obtain
network services.network services.
• Association:Association:
• Process wireless client join ke 802.11(AP) network,Process wireless client join ke 802.11(AP) network,
ini sama dengan seperti mengkoneksikan host/pcini sama dengan seperti mengkoneksikan host/pc
menggunakan kabel ke switch LAN.menggunakan kabel ke switch LAN.

• Wireless Routers:Wireless Routers:
• Wireless routers merupakan penggabungan fungsi dariWireless routers merupakan penggabungan fungsi dari
access point, Ethernet switch, dan router.access point, Ethernet switch, dan router.
• The Linksys WRT54GL is most commonly used as aThe Linksys WRT54GL is most commonly used as a
small business or residential wireless access device.small business or residential wireless access device.
• Beban pada perangkat diusahakan cukup rendahBeban pada perangkat diusahakan cukup rendah
sehingga akan dapat mengelola penyediaan WLAN,sehingga akan dapat mengelola penyediaan WLAN,
802,3 Ethernet, dan terhubung ke ISP dengan baik .802,3 Ethernet, dan terhubung ke ISP dengan baik .

Configurable Wireless ParametersConfigurable Wireless Parameters
• Configurable Wireless Parameters:Configurable Wireless Parameters:
802.11g is802.11g is backwardbackward
compatiblecompatible with 802.11.b.with 802.11.b.
MixedMixed mode supports both.mode supports both.
802.11g is802.11g is backwardbackward
compatiblecompatible with 802.11.b.with 802.11.b.
MixedMixed mode supports both.mode supports both.

Wireless OperationWireless Operation
AA shared service set identifier (SSID)shared service set identifier (SSID) is a uniqueis a unique
identifier that client devices use to distinguish betweenidentifier that client devices use to distinguish between
multiple wireless networks in the same vicinity.multiple wireless networks in the same vicinity.
AA shared service set identifier (SSID)shared service set identifier (SSID) is a uniqueis a unique
identifier that client devices use to distinguish betweenidentifier that client devices use to distinguish between
multiple wireless networks in the same vicinity.multiple wireless networks in the same vicinity.
Several access pointsSeveral access points
can share an SSID.can share an SSID.
Several access pointsSeveral access points
can share an SSID.can share an SSID.
Alphanumeric, case-sensitive,Alphanumeric, case-sensitive,
from 2 to 32 characters.from 2 to 32 characters.
Alphanumeric, case-sensitive,Alphanumeric, case-sensitive,
from 2 to 32 characters.from 2 to 32 characters.

Wireless OperationWireless Operation
The IEEE 802.11 standard establishes theThe IEEE 802.11 standard establishes the
channelization schemechannelization scheme for the usefor the use
of the unlicensedof the unlicensed ISM RF bandsISM RF bands in WLANs.in WLANs.
TheThe 2.4 GHz2.4 GHz band is broken down intoband is broken down into
11 channels11 channels for North Americafor North America
andand 13 channels13 channels for Europe.for Europe.
The IEEE 802.11 standard establishes theThe IEEE 802.11 standard establishes the
channelization schemechannelization scheme for the usefor the use
of the unlicensedof the unlicensed ISM RF bandsISM RF bands in WLANs.in WLANs.
TheThe 2.4 GHz2.4 GHz band is broken down intoband is broken down into
11 channels11 channels for North Americafor North America
andand 13 channels13 channels for Europe.for Europe.
Each arc represents 1 channel.Each arc represents 1 channel.Each arc represents 1 channel.Each arc represents 1 channel.
5 MHz overlap5 MHz overlap5 MHz overlap5 MHz overlap
Best practices for WLANs that requireBest practices for WLANs that require
multiple access points are set to usemultiple access points are set to use
non-overlapping channelsnon-overlapping channels..
Best practices for WLANs that requireBest practices for WLANs that require
multiple access points are set to usemultiple access points are set to use
non-overlapping channelsnon-overlapping channels..
3 Access Points3 Access Points3 Access Points3 Access Points
Many access points can automatically select aMany access points can automatically select a
channel based on adjacent channel use.channel based on adjacent channel use.
Some products continuously monitor the radio spaceSome products continuously monitor the radio space
to adjust the channel settings dynamically in responseto adjust the channel settings dynamically in response
to environmental changes.to environmental changes.
Many access points can automatically select aMany access points can automatically select a
channel based on adjacent channel use.channel based on adjacent channel use.
Some products continuously monitor the radio spaceSome products continuously monitor the radio space
to adjust the channel settings dynamically in responseto adjust the channel settings dynamically in response
to environmental changes.to environmental changes.

Wireless TopologiesWireless Topologies
• WLANsWLANs dapat mengakomodasi berbagai jaringan topologi.dapat mengakomodasi berbagai jaringan topologi. ..
• When describing these topologies, theWhen describing these topologies, the fundamentalfundamental
building blockbuilding block of the IEEE 802.11 WLAN architecture isof the IEEE 802.11 WLAN architecture is
thethe basic service setbasic service set (BSS).(BSS).
• BSS:BSS:
• Sekelompok stations yang dapat salingSekelompok stations yang dapat saling
berkomunikasi satu sama lainnya.berkomunikasi satu sama lainnya.
• Three Types:Three Types:
• Ad Hoc (Independent Basic Service Set –Ad Hoc (Independent Basic Service Set – IBSSIBSS))
• Basic Service Set (Basic Service Set (BSSBSS))
• Extended Service Set (Extended Service Set (ESSESS))

• Ad Hoc:Ad Hoc:
• Wireless networks can operate without access points.Wireless networks can operate without access points.
• Client stations which are configured to operate in ad hocClient stations which are configured to operate in ad hoc
modemode configure the wireless parameters betweenconfigure the wireless parameters between
themselvesthemselves..

• Basic Service Sets (BSS):Basic Service Sets (BSS):
• Access points provide an infrastructure that adds servicesAccess points provide an infrastructure that adds services
and improves the range for clients.and improves the range for clients.
• A single access point in infrastructure mode manages theA single access point in infrastructure mode manages the
wireless parameters and the topology is simply a BSS.wireless parameters and the topology is simply a BSS.
• The coverage area forThe coverage area for both an IBSS or a BSSboth an IBSS or a BSS is theis the
basic service area (BSA)basic service area (BSA)..
Basic Service AreaBasic Service AreaBasic Service AreaBasic Service Area

• Extended Service Sets (ESS):Extended Service Sets (ESS):
• When a single BSS provides insufficient RF coverage,When a single BSS provides insufficient RF coverage,
one or more can be joined through a common distributionone or more can be joined through a common distribution
system into an extended service set (ESS).system into an extended service set (ESS).
• One BSS is differentiated from another by theOne BSS is differentiated from another by the BSSBSS
identifier (BSSID)identifier (BSSID)..
• The MAC address of the access point.The MAC address of the access point.
• The coverage area is theThe coverage area is the extended service area (ESA)extended service area (ESA)..
Different MAC AddressesDifferent MAC Addresses
= different BSSIDs.= different BSSIDs.
Different MAC AddressesDifferent MAC Addresses
= different BSSIDs.= different BSSIDs.

• Common Distribution System:Common Distribution System:
• AllowsAllows multiple access pointsmultiple access points dalam ESS untuk menjadidalam ESS untuk menjadi
single BSSsingle BSS..
• An ESS generally includes aAn ESS generally includes a common SSIDcommon SSID to allow ato allow a
user touser to roamroam from access point to access point.from access point to access point.
• CellsCells represent the coverage area provided by a singlerepresent the coverage area provided by a single
channel.channel.
• An ESS should have 10 to 15 percent overlapAn ESS should have 10 to 15 percent overlap
between cells.between cells.
• Roaming capability created by using non-overlappingRoaming capability created by using non-overlapping
channels (e.g. one cell on channel 1 and the other onchannels (e.g. one cell on channel 1 and the other on
channel 6).channel 6).

Wireless AssociationWireless Association
• Bagian terpenting dari proses 802.11 adalah process
discovering WLAN & melakukan koneksi ke WLAN tersebut.
• Primary componentsnya adalah:
• Beacons: Frame yang digunakan oleh jaringan WLAN
untuk mengiklankan keberadaannya.
• Probes: Frame yang digunakan oleh klien WLAN untuk
menemukan jaringan mereka.
• Authentication: Left over from the original 802.11
standard, but still required.
• Association: Membangun data link antara jalur akses
WLAN dan klien/user.

• Beacons:Beacons:
• Frames used by the WLAN network to advertise itsFrames used by the WLAN network to advertise its
presence.presence.
Satu-satunya bagian dari prosesSatu-satunya bagian dari proses
yang dapat disiarkan secarayang dapat disiarkan secara
teratur.teratur. Not necessarily enabled.Not necessarily enabled.
Satu-satunya bagian dari prosesSatu-satunya bagian dari proses
yang dapat disiarkan secarayang dapat disiarkan secara
teratur.teratur. Not necessarily enabled.Not necessarily enabled.

• Before an 802.11 client can send data over a WLAN network,Before an 802.11 client can send data over a WLAN network,
it goes through the followingit goes through the following three-stagethree-stage process:process:
• Step 1:Step 1: 802.11 Probing.802.11 Probing.
• Step 2:Step 2: Authentication.Authentication.
• Step 3:Step 3: Association.Association.

• Step 1:Step 1: 802.11 Probing802.11 Probing
• Clients search for aClients search for a specificspecific network by:network by:
• Sending aSending a probe request out on multiple channelsprobe request out on multiple channels..
• Specifies the network nameSpecifies the network name (SSID)(SSID) and bit rates.and bit rates.
• A typical WLAN client is configured with a desiredA typical WLAN client is configured with a desired
SSID.SSID.
• Client is simply trying toClient is simply trying to discoverdiscover available WLANs:available WLANs:
• Sends out a probe request withSends out a probe request with no SSIDno SSID..
• All access points that areAll access points that are configured to respondconfigured to respond to thisto this
type of query respond.type of query respond.
• WLANs denganWLANs dengan broadcast SSID feature disabledbroadcast SSID feature disabled tidaktidak
akan meresponakan merespon

• Step 2:Step 2: AuthenticationAuthentication
• 802.11 was originally developed with 2 authentication802.11 was originally developed with 2 authentication
mechanisms.mechanisms.
1.1. Open Authentication:Open Authentication:
• A NULL authenticationA NULL authentication
• The client says "authenticate me“.The client says "authenticate me“.
• The access point responds with "yes“.The access point responds with "yes“.
• Ini merupakan mechanism yang digunakanIni merupakan mechanism yang digunakan
secara umum oleh 802.11 deployments.secara umum oleh 802.11 deployments.

2.2. Shared Key Authentication:Shared Key Authentication:
• Based on a key that is shared between the clientBased on a key that is shared between the client
station and the access point called the Wiredstation and the access point called the Wired
Equivalency ProtectionEquivalency Protection (WEP)(WEP) key.key.
• Bentuk perlindungan ini pada dasarnya menggunakanBentuk perlindungan ini pada dasarnya menggunakan
kunci enkripsi untuk melindungi data yang dikirim darikunci enkripsi untuk melindungi data yang dikirim dari
dan ke jaringan WLAN untuk mencegah penggunadan ke jaringan WLAN untuk mencegah pengguna
tanpa izin dapat mengakses jaringan.tanpa izin dapat mengakses jaringan.
• WEP needs to be included in client and access pointWEP needs to be included in client and access point
implementations for standards compliance but it isimplementations for standards compliance but it is notnot
used or recommendedused or recommended..

• Step 3:Step 3: 802.11 Association802.11 Association
• Finalizes theFinalizes the security and bit rate optionssecurity and bit rate options..
• Establishes the data linkEstablishes the data link between the WLAN client andbetween the WLAN client and
the access point.the access point.
• The client learns theThe client learns the BSSID (MAC Address)BSSID (MAC Address) of the accessof the access
point.point.
• Access point maps a logical port known as theAccess point maps a logical port known as the
association identifier (AID)association identifier (AID) to the WLAN client.to the WLAN client.
• AID is equivalent to a port on a switch.AID is equivalent to a port on a switch.
• Association identifier (AID)Association identifier (AID) allows the infrastructureallows the infrastructure
switch to keep track of frames destined for the WLANswitch to keep track of frames destined for the WLAN
client so that they can be forwarded.client so that they can be forwarded.

Planning the Wireless LANPlanning the Wireless LAN
Perlu ada rencana yang terdokumentasi dengan baikPerlu ada rencana yang terdokumentasi dengan baik
sebelum jaringan nirkabel dapat diimplementasikan. .sebelum jaringan nirkabel dapat diimplementasikan. .
1.1. Number of Users:Number of Users:
• Ini bukanlah perhitungan jumlah user secara sederhana.Ini bukanlah perhitungan jumlah user secara sederhana.
• Karena akan dipengaruhi lokasi geographical layoutKarena akan dipengaruhi lokasi geographical layout
dimana user berada.dimana user berada.
1.1. Data Rates:Data Rates:
• RF merupakan shared medium dan jika semakinRF merupakan shared medium dan jika semakin
banyak pengguna maka akan mempengaruhi RFbanyak pengguna maka akan mempengaruhi RF
tersebut.tersebut.
• Untuk itu “Untuk itu “Use non-overlapping channelsUse non-overlapping channels” in an ESS.” in an ESS.
1.1. Rencanakan jaringan Anda untuk cakupan RF yang tepatRencanakan jaringan Anda untuk cakupan RF yang tepat
dalam sebuah network ESS .dalam sebuah network ESS .

4.4. Location of Access Points:Location of Access Points:
• You may not be able to simply draw coverage areaYou may not be able to simply draw coverage area
circles and drop them over a plan.circles and drop them over a plan.
• Do access points use existing wiring?Do access points use existing wiring?
• Position access points:Position access points:
• Above obstructions.Above obstructions.
• Vertically near the ceiling in the center of eachVertically near the ceiling in the center of each
coverage area, if possible.coverage area, if possible.
• Lokasi dimana user akan bekerja. For example,Lokasi dimana user akan bekerja. For example,
conference rooms are typically a better location forconference rooms are typically a better location for
access points than a hallway.access points than a hallway.

5.5. Coverage Area of Access Points:Coverage Area of Access Points:
• Memperkirakan cakupan area access point yangMemperkirakan cakupan area access point yang
diharapkan.diharapkan.
• This value varies depending on:This value varies depending on:
• The WLAN standard or mix of standards that you areThe WLAN standard or mix of standards that you are
deploying.deploying.
• The nature of the facility.The nature of the facility.
• The transmit power that the access point.The transmit power that the access point.
6.6. Based on your plan, tempatkan access points agar coverageBased on your plan, tempatkan access points agar coverage
circles tidak terdapat banyak overlapping.circles tidak terdapat banyak overlapping.

Number of Access PointsNumber of Access PointsNumber of Access PointsNumber of Access Points
20,000 Sq. Ft.20,000 Sq. Ft.
(1860 Sq. Meters)(1860 Sq. Meters)
20,000 Sq. Ft.20,000 Sq. Ft.
Minimum ofMinimum of 6 Mbps6 Mbps
802.11b throughput802.11b throughput forfor
each Basic Serviceeach Basic Service
Area (BSA)Area (BSA)
Minimum ofMinimum of 6 Mbps6 Mbps
802.11b throughput802.11b throughput forfor
each Basic Serviceeach Basic Service
Area (BSA)Area (BSA)
Can be achieved with aCan be achieved with a
coverage area ofcoverage area of 5,000 Sq. Ft.5,000 Sq. Ft.
Can be achieved with aCan be achieved with a
coverage area ofcoverage area of 5,000 Sq. Ft.5,000 Sq. Ft.
20,000 Sq. Ft. with a20,000 Sq. Ft. with a
coverage of 5,000 Sq. Ft.coverage of 5,000 Sq. Ft.
results inresults in 4 Access4 Access
PointsPoints..
20,000 Sq. Ft. with a20,000 Sq. Ft. with a
coverage of 5,000 Sq. Ft.coverage of 5,000 Sq. Ft.
results inresults in 4 Access4 Access
PointsPoints..

50 foot (15 Meter) Radius50 foot (15 Meter) Radius50 foot (15 Meter) Radius50 foot (15 Meter) Radius
71 foot (22 Meter) Square71 foot (22 Meter) Square71 foot (22 Meter) Square71 foot (22 Meter) Square
Dimension of Coverage AreaDimension of Coverage AreaDimension of Coverage AreaDimension of Coverage Area

Location of Access PointsLocation of Access PointsLocation of Access PointsLocation of Access Points

Expl sw chapter_07_wireless rev.01

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