Understanding Wireless Networks Basics

Aug 14, 2024

CCNA Wireless Fundamentals Lecture Notes

Introduction

  • Welcome to Jeremy’s IT Lab, a complete course for CCNA.
  • Focus on wireless networks fundamentals.
  • Topics: Access points, non-overlapping Wi-Fi channels, SSID, and RF.
  • Overview and introduction to wireless networks.

Radio Frequency (RF)

  • RF: Range of electromagnetic wave frequencies.
  • Used for AM/FM radio, microwaves, radar, Wi-Fi.
  • Wireless LANs use Wi-Fi (IEEE 802.11 standards).

Wireless LAN Fundamentals

  • Wireless LANs differ from wired LANs.
  • Wi-Fi: Trademark of the Wi-Fi Alliance (tests and certifies 802.11 compliance).
  • Common issues: all devices in range receive frames, data privacy concerns.
  • Encryption is essential for data privacy in wireless LANs.
  • CSMA/CA (Collision Avoidance) used to avoid data collisions.

Wireless Signal Behavior

  • Signal issues: Absorption, Reflection, Refraction, Diffraction, Scattering.
  • Interference: Other devices using the same channels.

Electromagnetic Waves

  • Waves measured by amplitude and frequency.
  • Frequency units: Hertz (Hz), Kilohertz (kHz), Megahertz (MHz), Gigahertz (GHz).
  • Radio Frequency range: 30 Hz to 300 GHz.

Wi-Fi Frequency Bands

  • 2.4 GHz band: 2.4 GHz to 2.4835 GHz.
  • 5 GHz band: 5.150 GHz to 5.825 GHz.
  • Channel bonding possible, but not required knowledge for CCNA.
  • Channels in 2.4 GHz band overlap, recommended use of channels 1, 6, 11 to avoid interference.
  • 5 GHz band channels are non-overlapping.

Wi-Fi Standards

  • Different IEEE 802.11 standards (a, b, g, n, ac, ax; Wi-Fi 4, 5, 6 respectively).
  • Memorize standards, frequencies, and data rates.

Service Sets

  • Service Sets: Groups of wireless network devices with the same SSID.
  • Types of Service Sets:
    • Independent Basic Service Set (IBSS): Ad hoc networks without AP.
    • Basic Service Set (BSS): Infrastructure set with APs, uses BSSID.
    • Extended Service Set (ESS): Multiple BSSs connected by a wired network, allows roaming.
    • Mesh Basic Service Set (MBSS): Mesh networks with one RAP and multiple MAPs.

AP Modes

  • Repeater Mode: Extends range, may reduce throughput.
  • Workgroup Bridge (WGB): Connects wired devices to wireless network.
  • Outdoor Bridge: Connects networks over long distances, point-to-point or point-to-multipoint configurations.

Summary

  • Covered wireless networks basics: RF, Wi-Fi standards, signal issues.
  • More topics: Network architectures, security, configuration in future lectures.

Quiz Answers

  1. Channels 1, 6, 11 for non-overlapping in 2.4 GHz band.
  2. AP connects wireless devices to a wired network (DS).
  3. Bands used: 2.4 GHz, 5 GHz.
  4. ESS true statements: Unique BSSID for each BSS, roaming for seamless connectivity.
  5. AP with multiple BSSs must have unique BSSIDs.