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Wireless LAN Technology

Wireless LAN Technology. Introduction. Why look at WLANs? Who Cares? Maybe he hasn’t noticed, but we develop software for a living, not wire up networks…. Topics of Discussion. What is a Wireless LAN How does a WLAN work? Differing Technologies within the implementation of WLANs

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Wireless LAN Technology

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  1. Wireless LAN Technology

  2. Introduction • Why look at WLANs? • Who Cares? • Maybe he hasn’t noticed, but we develop software for a living, not wire up networks…

  3. Topics of Discussion • What is a Wireless LAN • How does a WLAN work? • Differing Technologies within the implementation of WLANs • Advantages/Disadvantages • How do I steal my rich stock broker neighbor’s weekly stock tips?

  4. What is a Wireless LAN • A network of computers and other devices not bound by the normal constraints and costs that a traditional LAN involves

  5. How does a WLAN work? • Data sent through the air using radio frequency • Broken down into two basic components: Transmitter/Transceiver • Transmitters/Transceivers transmit data at the same radio frequency

  6. Transmitters • Access Points(AP) • Network device responsible for converting wired LAN signal into radio frequency • Good for supporting users within a couple of hundred feet without degradation of signal

  7. AP Usability • Up to three Access Points may be combined to create larger field • Automatic strongest field detection allows user to wander around with changeovers staged transparently • If longer range is necessary, directional antennae can be substituted in place of AP

  8. Transceivers • Wireless Ethernet cards • Manufactured for both PCMCIA/PCI slots • Installs just like regular LAN adapters • Be careful for the antennae…

  9. The 802.11/11b Standard • Standard developed for WLAN technologies • Lays out: • FH – Frequency Hopping • DSSS – Direct Sequence Spread Spectrum • Diffused infrared

  10. Frequency Hopping(FH) • Uses Bursts of signals • Maintains a single logical channel • Is one of the two recommended RF platforms found in the 802.11 standard, has been omitted for new 802.11b platform

  11. Direct Sequence Spread Spectrum(DSSS) • Has been adopted in both the 802.11/11b standard • The use of a wider frequency range while sending data allows for higher bandwidth • Breaks up data into small pieces, then transmits through a range of frequencies

  12. Security • RF signals are unfortunately prone to interception by unwanted parties(intentional/unintentional) • FH quickly switches from frequency to frequency making it hard to keep up • DSSS is scrambled, reducing risk of unintentional interception(900 mhz phones, military comm, etc…)

  13. The Big Gun • WEP – Wired Equivalent Privacy • Uses a key on each end, much like an RSA model • This implementation is the answer to a lot of firms crying out for privacy • Allows for Geographically dependent security

  14. Performance • 802.11 used to sustain at most a 6mb/s connection • New 802.11b standard commands closer to 11mb/s • Signal degrades with distance depending primarily on environment(open field vs. lead shielding)

  15. Disadvantages • Limited range(500 ft, up to 1500 with additional AP hardware) • Bandwidth quickly eaten by too many machines(load balancing has not yet fully matured within this technology) • Limited Maximum Bandwidth (11mb/s)

  16. Advantages • Easy, convenient setup • Highly cost effective for small to mid-range shops, or as add-ons to large enterprise networks • Minimal downtime for relocation of computer away from cubicle with annoying person next door

  17. Get Rich Quick Scheme • Now… How to get those stock quotes…

  18. Use a Hidden Web Cam • Or just go ask him, either way, it is substantially easier and cheaper than trying to hack into a wireless LAN using DSSS combined with WEP

  19. Any Questions?

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