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Wi-Fi Technology Wi-Fi Technology
AgendaAgenda• IntroductionIntroduction• Wi-Fi TechnologiesWi-Fi Technologies• Wi-Fi ArchitectureWi-Fi Architecture• Wi-Fi Network ElementsWi-Fi Network Elements• How a Wi-Fi Network WorksHow a Wi-Fi Network Works• Wi-Fi Network TopologiesWi-Fi Network Topologies• Wi-Fi ConfigurationsWi-Fi Configurations• Applications of Wi-FiApplications of Wi-Fi• Wi-Fi SecurityWi-Fi Security• Advantages/ Disadvantages of Wi-FiAdvantages/ Disadvantages of Wi-Fi
IntroductionIntroduction• Wireless Technology is an alternative to Wired Wireless Technology is an alternative to Wired
Technology, which is commonly used, for Technology, which is commonly used, for connecting devices in wireless mode.connecting devices in wireless mode.
• Wi-Fi (Wireless Fidelity) is a generic term that Wi-Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications refers to the IEEE 802.11 communications standard for Wireless Local Area Networks standard for Wireless Local Area Networks (WLANs).(WLANs).
• Wi-Fi Network connect computers to each other, Wi-Fi Network connect computers to each other, to the internet and to the wired network.to the internet and to the wired network.
The Wi-Fi TechnologyThe Wi-Fi Technology
Wi-Fi Networks use Radio Technologies to Wi-Fi Networks use Radio Technologies to transmit & receive data at high speed:transmit & receive data at high speed:
• IEEE 802.11bIEEE 802.11b• IEEE 802.11aIEEE 802.11a• IEEE 802.11gIEEE 802.11g
802.11 Physical Layer802.11 Physical Layer
There are three sublayers in physical layer:There are three sublayers in physical layer:
• Direct Sequence Spread Spectrum (DSSS)Direct Sequence Spread Spectrum (DSSS)• Frequency Hoping Spread Spectrum (FHSS)Frequency Hoping Spread Spectrum (FHSS)• Diffused Infrared (DFIR) - Wide angleDiffused Infrared (DFIR) - Wide angle
IEEE 802.11 Data Link LayerIEEE 802.11 Data Link Layer
The data link layer consists of two sublayers : The data link layer consists of two sublayers :
• Logical Link Control (LLC) Logical Link Control (LLC) • Media Access Control (MAC).Media Access Control (MAC).
802.11 uses the same 802.2 LLC and 48-bit addressing as other 802.11 uses the same 802.2 LLC and 48-bit addressing as other 802 LANs, allowing for very simple bridging from wireless to 802 LANs, allowing for very simple bridging from wireless to IEEE wired networks, but the MAC is unique to WLANs.IEEE wired networks, but the MAC is unique to WLANs.
Elements of a WI-FI NetworkElements of a WI-FI Network
• Access Point (AP) - Access Point (AP) - The AP is a wireless LAN The AP is a wireless LAN transceiver or “base station” that can connect one or many transceiver or “base station” that can connect one or many wireless devices simultaneously to the Internet. wireless devices simultaneously to the Internet.
• Wi-Fi cards - Wi-Fi cards - They accept the wireless signal and relay They accept the wireless signal and relay information.They can be internal and external.(e.g PCMCIA information.They can be internal and external.(e.g PCMCIA Card for Laptop and PCI Card for Desktop PC)Card for Laptop and PCI Card for Desktop PC)
• Safeguards - Safeguards - Firewalls and anti-virus software protect Firewalls and anti-virus software protect networks from uninvited users and keep information secure.networks from uninvited users and keep information secure.
How a Wi-Fi Network WorksHow a Wi-Fi Network Works• Basic concept is same as Walkie talkies.Basic concept is same as Walkie talkies.• A Wi-Fi hotspot is created by installing an access point A Wi-Fi hotspot is created by installing an access point
to an internet connection.to an internet connection.• An access point acts as a base station. An access point acts as a base station. • When Wi-Fi enabled device encounters a hotspot the When Wi-Fi enabled device encounters a hotspot the
device can then connect to that network wirelessly.device can then connect to that network wirelessly.• A single access point can support up to 30 users and A single access point can support up to 30 users and
can function within a range of 100 – 150 feet indoors and can function within a range of 100 – 150 feet indoors and up to 300 feet outdoors.up to 300 feet outdoors.
• Many access points can be connected to each other via Many access points can be connected to each other via Ethernet cables to create a single large network.Ethernet cables to create a single large network.
Wi-Fi Network TopologiesWi-Fi Network Topologies• AP-based topology (Infrastructure Mode)AP-based topology (Infrastructure Mode)
• Peer-to-peer topology (Ad-hoc Mode)Peer-to-peer topology (Ad-hoc Mode)
• Point-to-multipoint bridge topologyPoint-to-multipoint bridge topology
AP-based topologyAP-based topology• The client communicate through Access Point. The client communicate through Access Point. • BSA-RF coverage provided by an AP.BSA-RF coverage provided by an AP.• ESA-It consists of 2 or more BSA.ESA-It consists of 2 or more BSA.• ESA cell includes 10-15% overlap to allow ESA cell includes 10-15% overlap to allow
roaming.roaming.
Peer-to-peer topologyPeer-to-peer topology• AP is not required.AP is not required.• Client devices within Client devices within
a cell can a cell can communicate directly communicate directly with each other.with each other.
• It is useful for setting It is useful for setting up of a wireless up of a wireless network quickly and network quickly and easily.easily.
Point-to-multipoint bridge topologyPoint-to-multipoint bridge topologyThis is used to connect a LAN in one building to a LANs This is used to connect a LAN in one building to a LANs in other buildings even if the buildings are miles in other buildings even if the buildings are miles apart.These conditions receive a clear line of sight apart.These conditions receive a clear line of sight between buildings. The line-of-sight range varies based between buildings. The line-of-sight range varies based on the type of wireless bridge and antenna used as well on the type of wireless bridge and antenna used as well as the environmental conditions.as the environmental conditions.
Wi-Fi ConfigurationsWi-Fi Configurations
Wi-Fi ConfigurationsWi-Fi Configurations
Wi-Fi ConfigurationsWi-Fi Configurations
Wi-Fi ApplicationsWi-Fi Applications
• HomeHome• Small Businesses or SOHOSmall Businesses or SOHO• Large Corporations & CampusesLarge Corporations & Campuses• Health CareHealth Care• Wireless ISP (WISP)Wireless ISP (WISP)• TravellersTravellers
Wi-Fi Security ThreatsWi-Fi Security Threats
• Wireless technology doesn’t remove any Wireless technology doesn’t remove any old security issues, but introduces new old security issues, but introduces new onesones• EavesdroppingEavesdropping• Man-in-the-middle attacksMan-in-the-middle attacks• Denial of ServiceDenial of Service
Wi-Fi Security Wi-Fi Security
The requirements for Wi-Fi network The requirements for Wi-Fi network security can be broken down into two security can be broken down into two primary components:primary components:
• AuthenticationAuthentication User AuthenticationUser Authentication Server AuthenticationServer Authentication
• PrivacyPrivacy
Wi-Fi Security TechniquesWi-Fi Security Techniques• Service Set Identifier (SSID)Service Set Identifier (SSID)
• Wired Equivalent Privacy (WEP)Wired Equivalent Privacy (WEP)
• 802.1X Access Control802.1X Access Control
• Wireless Protected Access (WPA)Wireless Protected Access (WPA)
• IEEE 802.11iIEEE 802.11i
802.1x Access Control802.1x Access Control
AdvantagesAdvantages• MobilityMobility• Ease of InstallationEase of Installation• FlexibilityFlexibility• CostCost• ReliabilityReliability• SecuritySecurity• Use unlicensed part of the radio spectrumUse unlicensed part of the radio spectrum• RoamingRoaming• SpeedSpeed
LimitationsLimitations
• InterferenceInterference• Degradation in performanceDegradation in performance• High power consumptionHigh power consumption• Limited rangeLimited range
