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CCNA3-1 Chapter 7-1 Basic Wireless Concepts and Basic Wireless Concepts and Configuration Configuration The Wireless LAN The Wireless LAN
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Page 1: 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

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CCNA3-2 Chapter 7-1

• Perkembang Networking saat ini sudah dapat mendukung aktifitas Perkembang 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 restricted no longer restricted lokasi lokasi kerja yang tetap ataupun dibatasi oleh waktu. kerja yang tetap ataupun dibatasi oleh waktu.

• Kita saat ini membutuhkan suatu network yang selalu Kita saat ini membutuhkan suatu network yang selalu terkoneksi untuk dapat melakukan komunikasi dan aktifitas terkoneksi 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 kita Dengan networking yang dapat mendukung aktifitas kita secara mobile, maka saat ini kita dapat melakukan pekerjaan secara mobile, maka saat ini kita dapat melakukan pekerjaan seperti check seperti check e-mail, voice mail, and the status of productse-mail, voice mail, and the status of products menggunakan personal digital assistants (PDAs) atau menggunakan 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 dari dirumah-rumah saat ini sudah beralih dari modem dial-up lama ke dedicated DSL atau cable service modem dial-up lama ke dedicated DSL atau cable service maupun handphone.maupun handphone.

Why Use Wireless?Why Use Wireless?

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CCNA3-3 Chapter 7-1

Why Use Wireless?Why Use Wireless?

• Pada awalnya networks komunikasi terbatas hanya pada Pada awalnya networks komunikasi terbatas hanya pada pertukaran informasi character based.pertukaran informasi character based.

• Communications antar computers (cross) tidak mudah Communications antar computers (cross) tidak mudah dilakukan dan memerlukan host/pc untuk keperluan dilakukan dan memerlukan host/pc untuk keperluan komunikasi transfer data sederhana.komunikasi transfer data sederhana.

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CCNA3-4 Chapter 7-1

Why Use Wireless?Why Use Wireless?

• Saat ini networks dapat membawa berbagai jenis tipe data Saat ini networks dapat membawa berbagai jenis tipe data information melalui banyak jenis device secara information melalui banyak jenis device secara SSIMULTANEOUSLY/bersamaanIMULTANEOUSLY/bersamaan..

• Kita mendapatkan response secara langsung dari lawan Kita 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

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CCNA3-5 Chapter 7-1

• Selain flexibility yang disediakan teknologi WLANs, Selain flexibility yang disediakan teknologi WLANs, keuntungan lainnya adalah keuntungan lainnya adalah reduced costsreduced costs..

• Moving persons within a building with a wireless Moving 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.

Why Use Wireless?Why Use Wireless?

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 Access Wireless 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.

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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 dan Namun saat ini pekerja banyak melakukan pekerjaan secara mobile dan ingin dapat mengakses ke network perusahaan untuk melakukan aktifitas ingin 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

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CCNA3-7 Chapter 7-1

• Wireless LAN dapat menjadi pilihan yang efektif, sebagai Wireless LAN dapat menjadi pilihan yang efektif, sebagai perpanjangan/yang menghubungkan kita ke Ethernet LAN.perpanjangan/yang menghubungkan kita ke Ethernet LAN.

Wireless LANsWireless LANs

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CCNA3-8 Chapter 7-1

Comparing a WLAN to a LANComparing a WLAN to a LAN

Network Architecture StandardsNetwork Architecture Standards

Physical MediaPhysical Media

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CCNA3-9 Chapter 7-1

Comparing a WLAN to a LANComparing a WLAN to a LAN

Wireless Access Points (AP) Wireless Access Points (AP) instead of a switch.instead of a switch.

Privacy Privacy IssuesIssues

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CCNA3-10 Chapter 7-1

Comparing a WLAN to a LANComparing a WLAN to a LAN

• 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

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CCNA3-11 Chapter 7-1

• Additional components and protocolsAdditional components and protocols yang digunakan pada 802.11 yang 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

Wireless Access Wireless Access Point (AP)Point (AP)

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CCNA3-12 Chapter 7-1

• 802.11 wireless LAN802.11 wireless LAN::• IEEE standard menentukan radio frequency (RF) untuk IEEE standard menentukan radio frequency (RF) untuk

kebutuhan unlicensed Industrial, Scientific, and Medical kebutuhan unlicensed Industrial, Scientific, and Medical (ISM) (ISM) berdasarkan frequency bands yang digunakan oleh berdasarkan frequency bands yang digunakan oleh Physical layerPhysical layer dan dan MAC sub-layerMAC sub-layer dari wireless links. dari wireless links.

• Typically frequency bands ini, dipilih berdasarkan Typically frequency bands ini, dipilih berdasarkan standart dari standart dari data ratedata rate-nya. -nya.

Wireless LAN StandardsWireless LAN Standards

Final ratification Final ratification expected in expected in

November, 2009November, 2009

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CCNA3-13 Chapter 7-1

• 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.

Wireless LAN StandardsWireless LAN Standards

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CCNA3-14 Chapter 7-1

2. Orthogonal Frequency Division Multiplexing (OFDM):2. Orthogonal Frequency Division Multiplexing (OFDM):Merupakan teknik mudulasi untuk komunikasi wireless broadband Merupakan teknik mudulasi untuk komunikasi wireless broadband dimasa yang akan datang, karena OFDM ini tahan melawan frekuensi dimasa yang akan datang, karena OFDM ini tahan melawan frekuensi selective fading dan interferensi narrowband dan efisien menghadapi selective fading dan interferensi narrowband dan efisien menghadapi multi-path delay spread. Untuk mencapai hal tersebut, OFDM membagi multi-path delay spread. Untuk mencapai hal tersebut, OFDM membagi aliran data high-rate menjadi aliran rate yang lebih rendah, yang aliran 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 menggunakan Sub-carrier dimodulasikan sendiri dengan menggunakan Phase Shift Phase 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.

Wireless LAN StandardsWireless LAN Standards

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CCNA3-15 Chapter 7-1

Wireless LAN StandardsWireless LAN Standards

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CCNA3-16 Chapter 7-1

Wireless LAN StandardsWireless LAN Standards

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CCNA3-17 Chapter 7-1

• 802.11a Standard:802.11a Standard:• OFDMOFDM modulation & menggunakan Frekusensi modulation & menggunakan Frekusensi 5 GHz5 GHz..

• Less likely to experience interferenceLess likely to experience interference than devices than devices that operate in the 2.4 GHz band because there are that 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.

Wireless LAN StandardsWireless LAN Standards

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CCNA3-18 Chapter 7-1

• 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

Wireless LAN StandardsWireless LAN Standards

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CCNA3-19 Chapter 7-1

• 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 to Up to 1111 Mb/s using Mb/s using DSSSDSSS..

• 802.11g:802.11g:• Up to Up to 5454 Mb/s using Mb/s using OFDMOFDM..

Wireless LAN StandardsWireless LAN Standards

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CCNA3-20 Chapter 7-1

• 2.4 GHz band:2.4 GHz band:• Advantage:Advantage:

• Jangkauan yang lebih baik dibanding band 5GHz karena Jangkauan yang lebih baik dibanding band 5GHz karena sinyalnya tidak mudah terhalang.sinyalnya tidak mudah terhalang.

• Disadvantage:Disadvantage:• Banyak perangkat lain menggunakan band ini sehingga Banyak 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).

Wireless LAN StandardsWireless LAN Standards

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CCNA3-21 Chapter 7-1

• 802.11n: (November 2009)802.11n: (November 2009)• Didesign untuk meningkatkan kecepatan data WLAN dan jangkauan Didesign untuk meningkatkan kecepatan data WLAN dan jangkauan

tanpa memerlukan daya tambahan atau alokasi RF band. tanpa memerlukan daya tambahan atau alokasi RF band. • Menggunakan Menggunakan multiple radios and antenna at endpointsmultiple radios and antenna at endpoints, dan , dan

masing-masing melakukan broadcasting dengan frequency yang masing-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 LAN StandardsWireless LAN Standards

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CCNA3-22 Chapter 7-1

• Wireless NICs:Wireless NICs:• The device that makes a client station capable of sending The 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 the Like an Ethernet NIC, the wireless NIC, using the

modulation technique it is configured to use, modulation technique it is configured to use, encodes a encodes a data stream onto an RF signaldata stream onto an RF signal. .

• Wireless NICs are most often associated with mobile Wireless NICs are most often associated with mobile devices, such as laptop computers.devices, such as laptop computers.

Wireless Infrastructure ComponentsWireless Infrastructure Components

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CCNA3-23 Chapter 7-1

Wireless Infrastructure ComponentsWireless Infrastructure Components

• Wireless Access Points:Wireless Access Points:• An access point is a Layer 2 device that functions like an 802.3 An access point is a Layer 2 device that functions like an 802.3

Ethernet hub.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 802.11 frame Converts the TCP/IP data packets from their 802.11 frame

encapsulation to the 802.3 Ethernet frame format.encapsulation to the 802.3 Ethernet frame format.• Clients must Clients must associateassociate with an access point to obtain network with an access point to obtain network

services.services.• Association:Association:

• Process wireless client join ke 802.11(AP) network, ini Process wireless client join ke 802.11(AP) network, ini sama dengan seperti mengkoneksikan host/pc sama dengan seperti mengkoneksikan host/pc menggunakan kabel ke switch LAN.menggunakan kabel ke switch LAN.

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CCNA3-24 Chapter 7-1

Wireless Infrastructure ComponentsWireless Infrastructure Components

• Wireless Routers:Wireless Routers:• Wireless routers merupakan penggabungan fungsi dari Wireless 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 a The 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 rendah Beban 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 .

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CCNA3-25 Chapter 7-1

Configurable Wireless ParametersConfigurable Wireless Parameters

• Configurable Wireless Parameters:Configurable Wireless Parameters:

802.11g is 802.11g is backward backward compatiblecompatible with 802.11.b. with 802.11.b.

MixedMixed mode supports both. mode supports both.

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CCNA3-26 Chapter 7-1

Wireless OperationWireless Operation

• Configurable Wireless Parameters:Configurable Wireless Parameters:

A A shared service set identifier (SSID)shared service set identifier (SSID) is a unique is a unique identifier that client devices use to distinguish between identifier that client devices use to distinguish between

multiple wireless networks in the same vicinity. multiple wireless networks in the same vicinity.

Several access points Several 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.

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CCNA3-27 Chapter 7-1

Wireless OperationWireless Operation

• Configurable Wireless Parameters:Configurable Wireless Parameters:

The IEEE 802.11 standard establishes theThe IEEE 802.11 standard establishes thechannelization schemechannelization scheme for the use for the use

of the unlicensed of the unlicensed ISM RF bandsISM RF bands in WLANs. in WLANs.

The The 2.4 GHz2.4 GHz band is broken down into band is broken down into11 channels11 channels for North America for North Americaand and 13 channels13 channels for Europe. for Europe.

Each arc represents 1 channel.Each arc represents 1 channel.

5 MHz overlap5 MHz overlap

Best practices for WLANs that require Best practices for WLANs that require multiple access points are set to use multiple access points are set to use

non-overlapping channelsnon-overlapping channels. .

3 Access Points3 Access PointsMany access points can automatically select a Many access points can automatically select a

channel based on adjacent channel use.channel based on adjacent channel use.Some products continuously monitor the radio space Some products continuously monitor the radio space

to adjust the channel settings dynamically in response to adjust the channel settings dynamically in response to environmental changes.to environmental changes.

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CCNA3-28 Chapter 7-1

Wireless TopologiesWireless Topologies

• WLANs WLANs dapat mengakomodasi berbagai jaringan topologi. dapat mengakomodasi berbagai jaringan topologi. ..• When describing these topologies, the When describing these topologies, the fundamental fundamental

building blockbuilding block of the IEEE 802.11 WLAN architecture is of the IEEE 802.11 WLAN architecture is thethe basic service set basic service set (BSS). (BSS).• BSS:BSS:

• Sekelompok stations yang dapat saling Sekelompok 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 – IBSS IBSS))• Basic Service Set (Basic Service Set (BSSBSS))• Extended Service Set (Extended Service Set (ESSESS))

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CCNA3-29 Chapter 7-1

Wireless TopologiesWireless Topologies

• 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 hoc Client stations which are configured to operate in ad hoc

mode mode configure the wireless parameters between configure the wireless parameters between themselvesthemselves. .

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CCNA3-30 Chapter 7-1

Wireless TopologiesWireless Topologies

• Basic Service Sets (BSS):Basic Service Sets (BSS):• Access points provide an infrastructure that adds services Access 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 the A 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 BSS both an IBSS or a BSS is the is the

basic service area (BSA)basic service area (BSA). .

Basic Service AreaBasic Service Area

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CCNA3-31 Chapter 7-1

Wireless TopologiesWireless Topologies

• 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 distribution one 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 the One BSS is differentiated from another by the BSS BSS identifier (BSSID)identifier (BSSID)..• The MAC address of the access point.The MAC address of the access point.

• The coverage area is the The coverage area is the extended service area (ESA)extended service area (ESA)..

Different MAC AddressesDifferent MAC Addresses= different BSSIDs.= different BSSIDs.

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CCNA3-32 Chapter 7-1

Wireless TopologiesWireless Topologies

• Common Distribution System:Common Distribution System:• Allows Allows multiple access pointsmultiple access points dalam ESS untuk menjadi dalam ESS untuk menjadi

single BSSsingle BSS..• An ESS generally includes a An ESS generally includes a common SSIDcommon SSID to allow a to allow a

user touser to roam roam from access point to access point. from access point to access point.• Cells Cells represent the coverage area provided by a single represent the coverage area provided by a single

channel. channel. • An ESS should have 10 to 15 percent overlap An ESS should have 10 to 15 percent overlap

between cells.between cells.• Roaming capability created by using non-overlapping Roaming capability created by using non-overlapping

channels (e.g. one cell on channel 1 and the other on channels (e.g. one cell on channel 1 and the other on channel 6).channel 6).

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CCNA3-33 Chapter 7-1

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.

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CCNA3-34 Chapter 7-1

Wireless AssociationWireless Association

• Beacons:Beacons:• Frames used by the WLAN network to advertise its Frames used by the WLAN network to advertise its

presence.presence.

Satu-satunya bagian dari proses Satu-satunya bagian dari proses yang dapat disiarkan secara yang dapat disiarkan secara

teratur. teratur. Not necessarily enabled.Not necessarily enabled.

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CCNA3-35 Chapter 7-1

Wireless AssociationWireless Association

• 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 following it 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.

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CCNA3-36 Chapter 7-1

Wireless AssociationWireless Association

• Step 1:Step 1: 802.11 Probing802.11 Probing• Clients search for a Clients search for a specific specific network by:network by:

• Sending a Sending a probe request out on multiple channelsprobe request out on multiple channels..• Specifies the network name Specifies the network name (SSID)(SSID) and bit rates. and bit rates.• A typical WLAN client is configured with a desired A typical WLAN client is configured with a desired

SSID. SSID. • Client is simply trying to Client is simply trying to discoverdiscover available WLANs: available WLANs:

• Sends out a probe request with Sends out a probe request with no SSIDno SSID..• All access points that are All access points that are configured to respondconfigured to respond to this to this

type of query respond.type of query respond.• WLANs dengan WLANs dengan broadcast SSID feature disabledbroadcast SSID feature disabled tidak tidak

akan meresponakan merespon

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CCNA3-37 Chapter 7-1

Wireless AssociationWireless Association

• Step 2:Step 2: AuthenticationAuthentication• 802.11 was originally developed with 2 authentication 802.11 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 digunakan Ini merupakan mechanism yang digunakan

secara umum oleh 802.11 deployments.secara umum oleh 802.11 deployments.

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CCNA3-38 Chapter 7-1

Wireless AssociationWireless Association

2.2. Shared Key Authentication:Shared Key Authentication:• Based on a key that is shared between the client Based on a key that is shared between the client

station and the access point called the Wired station and the access point called the Wired Equivalency Protection Equivalency Protection (WEP)(WEP) key. key.

• Bentuk perlindungan ini pada dasarnya menggunakan Bentuk perlindungan ini pada dasarnya menggunakan kunci enkripsi untuk melindungi data yang dikirim dari kunci enkripsi untuk melindungi data yang dikirim dari dan ke jaringan WLAN untuk mencegah pengguna dan 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 point WEP needs to be included in client and access point implementations for standards compliance but it is implementations for standards compliance but it is not not used or recommendedused or recommended..

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CCNA3-39 Chapter 7-1

Wireless AssociationWireless Association

• Step 3:Step 3: 802.11 Association802.11 Association• Finalizes the Finalizes the security and bit rate optionssecurity and bit rate options..• Establishes the data linkEstablishes the data link between the WLAN client and between 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 access of the access

point.point.• Access point maps a logical port known as the Access 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 infrastructure allows the infrastructure

switch to keep track of frames destined for the WLAN switch to keep track of frames destined for the WLAN client so that they can be forwarded.client so that they can be forwarded.

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Wireless AssociationWireless Association

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Perlu ada rencana yang terdokumentasi dengan baik Perlu 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 layout Karena akan dipengaruhi lokasi geographical layout

dimana user berada.dimana user berada.2.2. Data Rates:Data Rates:

• RF merupakan shared medium dan jika semakin banyak RF merupakan shared medium dan jika semakin banyak pengguna maka akan mempengaruhi RF tersebut. pengguna maka akan mempengaruhi RF tersebut.

• Untuk itu “Untuk itu “Use non-overlapping channelsUse non-overlapping channels” in an ESS.” in an ESS.3.3. Rencanakan jaringan Anda untuk cakupan RF yang tepat Rencanakan jaringan Anda untuk cakupan RF yang tepat

dalam sebuah network ESS .dalam sebuah network ESS .

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4.4. Location of Access Points:Location of Access Points:• You may not be able to simply draw coverage area You 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 each Vertically 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 for conference rooms are typically a better location for access points than a hallway.access points than a hallway.

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5.5. Coverage Area of Access Points:Coverage Area of Access Points:• Memperkirakan cakupan area access point yang Memperkirakan 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 are The 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 coverage Based on your plan, tempatkan access points agar coverage circles tidak terdapat banyak overlapping.circles tidak terdapat banyak overlapping.

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EndEnd

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Number of Access PointsNumber of Access Points

Planning the Wireless LANPlanning the Wireless LAN

20,000 Sq. Ft.20,000 Sq. Ft.(1860 Sq. Meters)(1860 Sq. Meters)

Minimum of Minimum of 6 Mbps 6 Mbps 802.11b throughput802.11b throughput for for

each Basic Service each Basic Service Area (BSA)Area (BSA)

Can be achieved with a Can be achieved with a coverage area of coverage area of 5,000 Sq. Ft. 5,000 Sq. Ft.

(465 Sq. Meters)(465 Sq. Meters)

20,000 Sq. Ft. with a 20,000 Sq. Ft. with a coverage of 5,000 Sq. Ft. coverage of 5,000 Sq. Ft.

results in results in 4 Access 4 Access PointsPoints. .

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50 foot (15 Meter) Radius50 foot (15 Meter) Radius

71 foot (22 Meter) Square71 foot (22 Meter) Square

Dimension of Coverage AreaDimension of Coverage Area

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Location of Access PointsLocation of Access Points