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Wifi- technology_moni


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Wifi- technology_moni

  2. 2. -:ACKNOWLEDGEMENT :- My respected teacher: Prof. Tarun Kumar Das 2
  3. 3.  # Introduction # Wi-Fi Technologies # Wi-Fi Architecture # Wi-Fi Network Elements # How a Wi-Fi Network Works # Wi-Fi Network Topologies # Wi-Fi Configurations # Applications of Wi-Fi # Wi-Fi Security # Conclusions # Reference # Bibliography 3
  4. 4. Introduction# Wireless Technology is an alternative to Wired Technology, which is commonly used, for connecting devices in wireless mode.# Wi-Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks 4
  5. 5. The Wi-Fi TechnologyWi-Fi Networks use RadioTechnologies to transmit &receive data at high speed:# IEEE 802.11b(1999)# IEEE 802.11a(2001)# IEEE 802.11g(2003) 5
  6. 6. 802.11 Physical Layer# There are three sub layers in physical layer: 1. Direct Sequence Spread Spectrum (DSSS) 2.Frequency Hoping Spread Spectrum (FHSS) 3.Diffused Infrared (DFIR) - Wide angle 6
  7. 7. DSSS# Direct sequence signaling technique divides the 2.4 GHz band into 11 22- MHz channels. Adjacent channels overlap one another partially, with three of the 11 being completely non- overlapping. Data is sent across one of these 22 MHz channels without hopping to other channels. 7
  8. 8. IEEE 802.11 Data LinkLayerThe data link layer consists of twosub-layers : * Logical Link Control (LLC) * Media Access Control (MAC). 802.11 uses the same 802.2 LLC and 48-bit addressing as other 802 LANs, allowing for very simple 8 bridging from wireless to IEEE
  9. 9. 802.11 Media Access Control# Carrier Sense Medium Access with collision avoidance protocol (CSMA/CA) ** Listen before talking ** Avoid collision by explicit Acknowledgement (ACK) ** Problem: additional overhead of ACK packets, so slow performance# Request to Send/Clear to Send (RTS/CTS) protocol • Solution for “hidden node” problem • Problem: Adds additional overhead by temporarily reserving the medium, so used for large size packets only retransmission would be expensive# Power Management 9
  10. 10. Elements of a WI-FI Network# Access Point (AP) - The AP is a wireless LAN transceiver or “base station” that can connect one or many wireless devices simultaneously to the Internet.# Wi-Fi cards - They accept the wireless signal and relay information.They can be internal and external.(e.g PCMCIA Card for Laptop and PCI Card for Desktop PC) 10# Safeguards - Firewalls and anti-virus
  11. 11. How a Wi-Fi Network Works# Basic concept is same as Walkie talkies.# A Wi-Fi hotspot is created by installing an access point to an internet connection.# An access point acts as a base station.# When Wi-Fi enabled device encounters a hotspot the device can then connect to that network wirelessly.# A single access point can support up to 30 users and can function within a range of 100 – 150 feet indoors and up to 300 feet outdoors.# Many access points can be connected to each 11
  12. 12. Wi-Fi Network Topologies# AP-based topology (Infrastructure Mode)# Peer-to-peer topology (Ad-hoc Mode)# Point-to-multipoint bridge topology 12
  13. 13. AP-based topology# The client communicate through Access Point.# BSA-RF coverage provided by an AP.# ESA-It consists of 2 or more BSA.# ESA cell includes 10-15% overlap to allow roaming. 13
  14. 14. Peer-to-peer topology# AP is not required.# Client devices within a cell can communicate directly with each other.# It is useful for setting up of a wireless network quickly and easily. 14
  15. 15. Point-to-multipoint bridge topologyThis is used to connect a LAN in one building toa LANs in other buildings even if the buildingsare miles apart . These conditions receive aclear line of sight between buildings. The line-of-sight range varies based on the type of wirelessbridge and antenna used as well as theenvironmental conditions. 15
  16. 16. Wi-Fi Configurations 16
  17. 17. Wi-Fi Applications# Home# Small Businesses or SOHO# Large Corporations & Campuses# Health Care# Wireless ISP (WISP)#Travellers 17
  18. 18. Wi-Fi Security TechniquesService Set Identifier (SSID)Wired Equivalent Privacy (WEP)802.1X Access ControlWireless Protected Access (WPA)IEEE 802.11i 18
  19. 19. Service Set Identifier (SSID)• SSID is used to identify an 802.11 network• It can be pre-configured or advertised in beacon broadcast• It is transmitted in clear text • Provide very little security 19
  20. 20. Wired Equivalent Privacy Or i g i n a l (WEP) t y s o l u t i s e c u r i o n o f f e r e d b y t h e I EEE 802.11 s t a n d a r d Us e s RC4 e n c r y p t i o n wi t h p r e -s h a r e d k e y s a n d 24 b i t i n i t i a l i z a t i o n v e c t o r s (I V ) k e y s c h e d u l e i s g e n e r a t e d b y c o n c a t e n a t i n g t h e s h a r e d s e c r e t k e y wi t h a r a n d o m g e n e r a t e d 24-b i t I V 32 b i t I C V (I n t e g r i t y c h e c k v a l u e ) No . o f b i t s i n k e y s c h e d u l e i s e q u a l t o s u m o f l e n g t h o 20 f t h e p l a i n t e x t a n d I CV
  21. 21. 802.1x Access• Designed as aControl network access general purpose control mechanism• Authenticate each client connected to AP (for WLAN) or switch port (for Ethernet)• Authentication is done with the RADIUS server, which ”tells” the access point whether access to controlled ports should be allowed or not • AP forces the user into an unauthorized state • user send an EAP start message • AP return an EAP message requesting the user’s identity • Identity send by user is then forwared to the authentication server by AP 21
  22. 22. Wireless Protected Access (WPA)# WPA is a specification of standard based, interoperablesecurity enhancements that strongly increase the level of dataprotection and access control for existing and future wirelessLAN system.• User Authentication • 802.1x • EAP# TKIP (Temporal Key Integrity Protocol) encryption • RC4, dynamic encryption keys (session based) • 48 bit IV • per packet key mixing function • Fixes all issues found from WEP• Uses Message Integrity Code (MIC) Michael • Ensures data integrity• Old hardware should be upgradeable to WPA# WPA comes in two flavors WPA-PSK 22 •
  23. 23.  Wi-Fi technology is the non- cable connection between the # Limitation: access point or router and • Degradation in the PC. The PC remotely connects to the internet performance without any wires or cables. • High power In some cases, Wi-Fi tech. requires you to have the WEP • consumption or WPA key to access. WEP/WPA is like the • Interference password to secure your • Limited range wireless router/ access point.# Advantages:• Mobility, Ease of Installation• Flexibility, Cost• Reliability,Security 23
  24. 24. #;_ylt=A8pWB_u3zVFPxVYAqUvuPXRG?ei=UTF-8&rd=r1&fr=yfp-t-704-s&p=wi-fi+technologies&SpellState=&fr2=sp-qrw-corr-top "Wi-Fi (wireless networking technology)". Encyclopedia 24
  25. 25. BIBLIOGRA PHY“Wi-Fi: Whats next", Paul S.HenryWireless Networking Handbook, Jim Geier.Wi-Fi (wireless networking technology)". Encyclopedia BritannicaSeoul Moves to Provide Free City-Wide Wi-Fi Service". Retrieved 1 April 25
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