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Wireless LAN

Wireless LAN. Wireless?. A wireless LAN or WLAN is a wireless local area network that uses radio waves as its carrier. The last link with the users is wireless, to give a network connection to all users in a building or campus. The backbone network usually uses cables. Common Topologies.

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Wireless LAN

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  1. Wireless LAN

  2. Wireless? • A wireless LAN or WLAN is a wireless local area network that uses radio waves as its carrier. • The last link with the users is wireless, to give a network connection to all users in a building or campus. • The backbone network usually uses cables

  3. Common Topologies The wireless LAN connects to a wired LAN • There is a need of an access point that bridges wireless LAN traffic into the wired LAN. • The access point (AP) can also act as a repeater for wireless nodes, effectively doubling the maximum possible distance between nodes.

  4. Major Factors • There are four major factors to consider before implementing a wireless network: • High availability • Scalability • Manageability • Open architecture

  5. 802.11 WLAN technologies • IEEE 802.11 standards and rates • IEEE 802.11 (1997) 1 Mbps and 2 Mbps (2.4 GHz band ) • IEEE 802.11b (1999) 11 Mbps (2.4 GHz band) = Wi-Fi • IEEE 802.11a (1999) 6, 9, 12, 18, 24, 36, 48, 54 Mbps (5 GHz band) • IEEE 802.11g (2001 ... 2003) up to 54 Mbps (2.4 GHz) backward compatible to 802.11b • IEEE 802.11 networks work on license free industrial, science, medicine (ISM) bands: 26 MHz 83.5 MHz 200 MHz 255 MHz 902 928 2400 2484 5150 5350 5470 5725 f/MHz 200 mW indoors only EIRP power in Finland 1 W 100 mW

  6. Building in Wireless LANs • Wireless LANs are an “addictive” technology • Strong commitment to Wireless LANs by technology heavy-weights • Cisco, IBM, Intel, Microsoft • Embedded market is growing • Laptop PC’s with “wireless inside” • PDA’s are next • The WLAN market is expanding from Industry-Specific Applications, to Universities, Homes, & Offices • Professional installers and technicians will be in demand

  7. “Business-Class”vs Consumer WLAN • Industry has segmented: consumer vs. business Cisco offers only “business-class” products: • Security • Upgradeability • Network management • Advanced features • Choice of antennas • Highest throughput • Scalability

  8. Benefits of WLANs

  9. WiFi

  10. Unlicensed Frequency Bands

  11. 2.5 GHz Service Circuit and Packet Data Cellular, CDPD, Mobitex, DataTac Broadband PCS Narrowband PCS Wireless Data Networks 50 Mbps Spread Spectrum Wireless LANs 10 Mbps Infrared Wireless LANs 2 Mbps 1 Mbps Data Rates 56 Kbps 19.6 Kbps Narrow Band Wireless LANs Satellite 9.6 Kbps Local Wide Coverage Area

  12. PAN LAN MAN WAN 802.11a, 11b, 11g HiperLAN2 802.11 MMDS, LMDS GSM, GPRS, CDMA, 2.5–3G Standards Bluetooth Speed <1 Mbps 2–54+ Mbps 22+ Mbps 10–384 Kbps Range Short Medium Medium–Long Long PDAs, Mobile Phones, Cellular Access Peer-to-Peer Device-to-Device Enterprise Networks Fixed, Last Mile Access Applications Wireless Technologies WAN (Wide Area Network) MAN (Metropolitan Area Network) LAN (Local Area Network) PAN (Personal Area Network)

  13. The IEEE 802.11 and supporting LAN Standards IEEE 802.2 Logical Link Control (LLC) OSI Layer 2 (data link) IEEE 802.11 Wireless IEEE 802.3 Carrier Sense IEEE 802.4 Token Bus IEEE 802.5 Token Ring MAC PHY OSI Layer 1 (physical) a b g ring bus star

  14. AP AP Internet 802.11 LAN architecture • wireless host communicates with base station • base station = access point (AP) • Basic Service Set (BSS) (aka “cell”) in infrastructure mode contains: • wireless hosts • access point (AP): base station • ad hoc mode: hosts only hub, switch or router BSS 1 BSS 2

  15. Figure 14.1 Basic service sets (BSSs)

  16. Figure 14.2 Extended service sets (ESSs)

  17. IEEE 802.11 Architecture • IEEE 802.11 defines the physical (PHY), logical link (LLC) and media access control (MAC) layers for a wireless local area network • 802.11 networks can work as • basic service set (BSS) • extended service set (ESS) • BSS can also be used in ad-hocnetworking Network LLC 802.11 MAC FHSS PHY DSSS IR LLC: Logical Link Control Layer MAC: Medium Access Control Layer PHY: Physical Layer FHSS: Frequency hopping SS DSSS: Direct sequence SS SS: Spread spectrum IR: Infrared light BSS: Basic Service Set ESS: Extended Service Set AP: Access Point DS: Distribution System DS, ESS ad-hoc network

  18. BSS and ESS • In ESS multiple access points connected by access points and a distribution system as Ethernet • BSSs partially overlap • Physically disjoint BSSs • Physically collocated BSSs (several antennas) Extended service set (ESS) Basic (independent) service set (BSS)

  19. Icons

  20. Icons

  21. Icons

  22. Wireless Technologies

  23. In Building WLAN

  24. Site to Site WLAN

  25. Radio Signal Interference

  26. Installation and Site Design Issues—Bridging

  27. Installation and Site Design Issues—WLAN

  28. 54 Mbps Speed 860 Kbps 1 and 2 Mbps 1 and 2 Mbps 11 Mbps Standards-based Network Proprietary 5 GHz Radio 900 MHz 2.4 GHz 2.4 GHz 1986 1998 2000 2002 1988 1990 1992 1994 1996 WLAN Evolution: 2000–Present • Warehousing • Retail • Healthcare • Education Businesses Home 802.11 Ratified 802.11a,b Ratified 802.11g Drafted • IEEE 802.11Begins Drafting

  29. Wi-Fi™ • Wi-Fi™ Alliance • Wireless Fidelity Alliance • 170+ members • Over 350 products certified • Wi-Fi’s™ Mission • Certify interoperability of WLAN products (802.11) • Wi-Fi™ is the “stamp of approval” • Promote Wi-Fi™ as the global standard

  30. WLAN Devices In-building Infrastructure • 1200 Series (802.11a and 802.11b) • 1100 Series (802.11b) • 350 Series (802.11b) not shown Bridging • 350 Series (802.11b) • BR350 • WGB350 • 1400 Series (802.11a)

  31. WLAN Devices Antenna • 2.4GHz • 5 GHz Antennas Clients • 350 Series (802.11b) • 5 GHz client adapter (802.11a) • Workgroup bridge (802.11b)

  32. Antennas • Indoor and Outdoor • WLAN and Bridging • Outdoor • Bridging 2.4 GHz 5 GHz

  33. Cable and Accessories

  34. 802.11-Enabled Phones • A cordless phone for the workplace • Cisco 7920 Wireless VoIP phone

  35. Beyond Laptops:Other 802.11-Enabled Devices Epson Printer HP iPAQ 5450 PDA • PDA’s • Phones • Printers • Projectors • Tablet PC’s • Security Cameras • Barcode scanners • Custom devices for vertical markets: • Healthcare • Manufacturing • Retail • Restaurants Compaq Tablet PC SpectraLink Phone HHP Barcode Scanner Sharp M25X Projector

  36. WLAN Markets

  37. Wireless LAN Security:Lessons “War Driving” Hacking into WEP Lessons: • Security must be turned on (part of the installation process) • Employees will install WLAN equipment on their own (compromises security of your entire network) • WEP keys can be easily broken (businesses need better security)

  38. Reliability and Connectivity

  39. Health Issues

  40. IEEE 802.11 Standards Activities • 802.11a: 5GHz, 54Mbps • 802.11b: 2.4GHz, 11Mbps • 802.11d: Multiple regulatory domains • 802.11e: Quality of Service (QoS) • 802.11f: Inter-Access Point Protocol (IAPP) • 802.11g: 2.4GHz, 54Mbps • 802.11h: Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) • 802.11i: Security • 802.11j: Japan 5GHz Channels (4.9-5.1 GHz) • 802.11k: Measurement

  41. WLAN Speeds & Frequencies 802.11g 2.4 GHz – OFDM/CCK 54 Mbps 802.11a 5 GHz – OFDM 54 Mbps 802.11b 2.4 GHz – CCK 11 Mbps Proprietary • IEEE 802.11a/b Ratified Jan’99 Jan’00 Jan’01 Jan’02 Jan’03 Jan’04

  42. Summary • Identify characteristics of Cisco Aironet 802.11a products. • Identify characteristics of Cisco Aironet 802.11b products.

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