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Networking Chapter 16

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Networking Chapter 16

  1. 1. Wireless Networking Chapter 16
  2. 2. Objectives• Explain wireless networking standards• Describe the process for implementing Wi- Fi networks• Describe troubleshooting techniques for wireless networks
  3. 3. • Historic/Conceptual – Wireless network uses radio waves as the media • Convenient • Sometimes the only network option • Same OSI layers as wired networks • Same [upper layer] protocols • Different methods for accessing the media • IEEE 802.11 wireless Ethernet standard – Wi-Fi – Most common implementation
  4. 4. • Wi-Fi Standards – Wi-Fi IEEE 802.11 • 802.11a • 802.11b • 802.11g • 802.11n
  5. 5. • Certified by Wi-Fi Alliance – 300 member companies – Design and manufacture wireless networking products – Certification should ensure compatibility between manufacturers – Troubleshooting section at end of this chapter brings out proprietary nature of some devices
  6. 6. • 802.11 – Standards define how wireless devices communicate – Some define how to secure communication – Each sub-standard has name of a IEEE subcommittee • Wireless Fidelity (Wi-Fi)
  7. 7. • Wireless Network Modes – Ad hoc mode • Also called peer-to-peer mode • Uses a mesh topology • Independent Basic Service Set (IBBS) – Two or more wireless nodes communicating in ad hoc mode• Infrastructure mode – Uses one or more access points – Similar to a wired star topology – Basic service set (BSS) • Served by a single WAP
  8. 8. • CSMA/CA – Carrier sense multiple access/collision avoidance (CSMA/CA) – Access method to allow multiple devices to share network media – Review how CSMA/CD works for wired networks • Each device listens on media – If no or low signal, media is free – If signal above a threshold, media is busy • If media is busy, device waits the length of the current frame plus the interframe space (IFS) period
  9. 9. • Wireless Networking Security – Problem • Easy-to-install devices have no default security • Network data packets are in radio waves – Easy to capture – Easy to read
  10. 10. • Three wireless security methods – MAC Address Filtering • Limits access to specific NICs • “Accepted users” list of MAC addresses • List in table stored in WAP • Data packets with other MAC addresses are rejected
  11. 11. – Wireless Authentication • Only users with proper credentials have access • Can use a centralized security database (like Active Directory) • Requires extra steps for wireless users
  12. 12. – Data Encryption • a. Data Encryption Using WEP – Wired Equivalent Privacy (WEP) – 64- or 128-bit encryption algorithm – Scrambles data packets – Problems » Easily cracked » Only works on two lowest OSI network layers

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