Question

Difficulty: HardWired and Wireless Network Issues

A network administrator is troubleshooting severe wireless performance degradation and intermittent disconnections in a dense office environment operating on the 2.4 GHz2.4\text{ GHz} band. An RF spectrum analyzer reveals that adjacent access points are broadcasting on channels 22, 55, and 88. Which of the following channel reconfigurations should the administrator implement to eliminate co-channel and adjacent-channel interference?

  1. Reconfigure the access points to broadcast exclusively on channels 1, 6, and 11.Answer
  2. B
    Reconfigure the access points to broadcast on adjacent even-numbered channels 2, 4, and 6.
  3. C
    Update the wireless access point configuration to dynamically assign IP addresses via DNS scope settings.
  4. D
    Replace the wireless access points with Layer 2 unmanaged switches to divide the wireless collision domains.

Answer

Reconfigure the access points to broadcast exclusively on channels 1, 6, and 11.
In 2.4 GHz wireless networks, each channel spans 20 to 22 MHz of frequency space, while channel centers are only 5 MHz apart. To avoid adjacent-channel interference between neighboring access points, administrators must select non-overlapping channels. The standard non-overlapping channel set for 2.4 GHz Wi-Fi is 1, 6, and 11.

Step-by-Step Solution

1
Analyze the reported symptom and environment setup
The network experiences RF interference on the 2.4 GHz band, with access points configured on channels 2, 5, and 8.
Each 2.4 GHz Wi-Fi channel is 20 MHz (or 22 MHz) wide with center frequencies spaced only 5 MHz apart.
2
Calculate channel overlap for 2.4 GHz Wi-Fi standards
Channels 2, 5, and 8 overlap with each other, causing severe adjacent-channel interference.
Adjacent-channel interference causes corrupt packets, collisions, and retransmissions.
3
Select non-overlapping channel scheme
Assign channels 1, 6, and 11 to adjacent access points.
Channels 1, 6, and 11 have 25 MHz separation between center frequencies (2412 MHz, 2437 MHz, 2462 MHz), preventing frequency overlap.

Key Concept

2.4 GHz Wi-Fi Channel Overlap and Non-Overlapping Channel Selection
Estimated Time:1m 30s
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