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7: Wireless Technologies

7: Wireless Technologies. Networking for Home & Small Business. Objectives. Understanding Wireless. Electromagnetic Spectrum Radio, TV, Light, X-Rays, Gamma Rays Each has a specific wavelength Like the distance between waves Wireless uses Electromagnetic Waves

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7: Wireless Technologies

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  1. 7: Wireless Technologies Networking for Home & Small Business

  2. Objectives

  3. Understanding Wireless • Electromagnetic Spectrum • Radio, TV, Light, X-Rays, Gamma Rays • Each has a specific wavelength • Like the distance between waves • Wireless uses Electromagnetic Waves • Same as carrying radio signals • We’ll discuss the most common wavelengths

  4. Infrared (IR) • Low energy • Can’t go through walls, short range (30’) • One to one communication • Wireless Mice & Keyboards, Remotes, PDA • Infrared Direct Access (IrDA) port

  5. IR & Your TV • Your TV remote has an infrared LED inside • Switches on & off to create 0’s and 1’s when you push a button • Push a button to send a 7 digit sequence of 0’s & 1’s • Sony TV Channel Up is 0000011, channel down is 0010001

  6. Radio Frequency (RF) • Wireless LAN, cordless phone, Bluetooth • LAN & Phone • Signal travels through walls, longer range, higher power • 900 MHz, 2.4 GHz and the 5 GHz frequency • Bluetooth • Low speed, short range, lower power • One to many devices • Uses 2.4GHz • Starting to use Bluetooth for wireless mice, etc.

  7. Activity- Which is it?

  8. Review • Bluetooth or RF. Which has higher power output? • RF • Two doctors are beaming their business cards to each other through their PDAs. Which signal is being used? • IR

  9. Wireless Benefits

  10. Wireless Limitations • Cordless Phones 2.4GHz Interference • Microwave Ovens Interference • Not as fast as wired • Security • Ease of Access • Size of Building • Range • Solid Walls

  11. WPAN • Wireless Personal Area Network • Used to connect wireless mice, keyboards & PDA’s to computer • IR or Bluetooth • Short Range • Device to device

  12. WLAN • Wireless Local Area Network • RF • IEEE 802.11 standards • Users connect to a wired network through an Access Point (AP) • Medium range

  13. Access Point • Between your wired equipment and your wireless devices

  14. WWAN • Wireless Wide Area Network • Cell phone network • GSM, CDMA • Long range • Government regulated

  15. Review

  16. Wireless Standards • Specifies data speed, range, RF spectrum • IEEE standards, Wi-Fi • 802.11a, 802.11b, 802.11g and 802.11n • Wi-Fi Alliance tests devices from manufacturer • Will work with other devices w/ same logo

  17. 802.11b • 1999 • 2.4GHz • 11Mbps • 150ft range indoors • 300 ft range outdoors

  18. 802.11a • 1999 • 5GHz • Unused at that time • Less congestion • 54Mbps (faster than B) • NOT compatible with b/g/n • 75ft-150ft range • Originally too expensive • Now hard to find

  19. 802.11g • 2003 • 2.4GHz • 54Mbps • 150ft range indoors • 300 ft range outdoors • Compatible with 802.11b

  20. 802.11n • In development • 2.4Ghz • Up to 750ft range • Backwards compatible b/g

  21. Wireless Components • Access Point • Connects wireless devices to wired network • Client • Any host device that connects to wireless • Also known as STA (station) • Bridge • Antenna

  22. Omni-Directional Antenna • Equally in all directions • Found on APs

  23. Directional Antenna • Concentrate signal in one direction • Better distance • Connects networks 25 miles or more apart • Bridge to Bridge- connects 2 networks wirelessly

  24. Want a bridge? Aironet 1400 • Find it on www.cdwg.com

  25. Activity

  26. 7.2.3 • WLANs & the SSID • 2 Forms of WLAN installations

  27. SSID-Service Set Identifier • Tells wireless devices which WLAN they belong to & which other devices they can communicate with • Case-sensitive & up to 32 characters • All of your devices MUST have same SSID • Broadcast or Not?

  28. Ad-hoc Mode- IBSS • Wireless devices can talk to each other without involving Access Point • Peer-to-peer or small networks • Less $$$, no AP

  29. Infrastructure Mode- BSS • Most used • AP/Router controls communication • Access to Internet • Basic Service Set (BSS) • Area covered by a single AP

  30. Cover More Areas • Connect many BSS’s to get expanded area • You get an ESS, Extended Service Set • Areas should overlap • Think about this school & coverage

  31. Question?

  32. Question?

  33. Question?

  34. Question?

  35. Lab Activity • 7.2.3.4 • READ THE INSTRUCTIONS!!! • Click Topology, then the host • View browser, follow directions

  36. Wireless Channels • Used to control multiple conversations • Like how all of your TV channels travel across a cable • Divides up the 2.4GHz for each conversation • Selection of channels is usually automatic • Sometimes they use a single wide channel to get more bandwidth

  37. Going to a Concert • General Admission compared to tickets for a seat • What’s the different experiences? • Wireless has a method to avoid collisions • A “ticketing” system

  38. Wireless Detecting Collisions • CSMA/CA • Reserves a channel for conversation • No one else may use that channel • Request to Send (RTS) to the AP • If available, a Clear to Send (CTS) is sent • OK to send • Broadcast is sent to all, notifying channel in use • ACK sent to AP to notify done • All devices see ACK & know channel is open

  39. CSMA/CA- (7.2.4.2)

  40. Activity- Setting the Channel • 7.2.4.3

  41. Configuring an AP

  42. Configuring the Client • What is a wireless host known as? • STA (station) • It’s a device with wireless NIC & software for it • Settings MUST match AP • SSID, security settings, and channel

  43. Configuring the Client- Software • As part of the OS • OR supplied with Wireless NIC • Contains link info, profiles, etc. • Usually the OS one is okay

  44. Now Test It… • Look at signal strength • Then test data transmission • Use the ping test • Ping another PC 1st • If that doesn’t work, ping the AP

  45. Lab 7.2.5.3 & 7.2.6.4 • Configure the AP and Wireless Client

  46. Wireless Security • Tradeoff: • Ease & convenience of availability vs. putting info to the airwaves • What can they do? • Use your Internet for FREE • Access your computers • Damage files • Steal private info • Solution…SET UP SECURITY!

  47. Why is security important? • It’s possible that an individual or a business owner can be held responsible for what an unauthorized user does with your network • Computer Fraud Law • Accessing a computer without authorization

  48. Which Security Measures?? • Use all of the following to secure your wireless network: • Change the router password from the default • Change the SSID & disable the broadcast • Use MAC Address Filtering • Authentication (PSK) • Encryption (WPA)

  49. Changing the Router Password!

  50. Change the Password!

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