Which three of these are considered Cisco RF guidelines for a proper VoWLAN deployment? (Choose three.)
Cisco RF guidelines for a proper VoWLAN deployment are critical to ensure that voice traffic is delivered with the required quality of service (QoS) and that the user experience is not impacted by network issues. The following are the explanations for the three guidelines mentioned in the question:
A. Cell edge should be -67 dBm with 20 to 30 percent overlap:
This guideline refers to the signal strength required at the cell edge, which is the point where the client device receives the weakest signal from the access point. Cisco recommends that the cell edge should have a signal strength of -67 dBm with 20 to 30 percent overlap between adjacent cells. The overlap is necessary to ensure seamless roaming between cells and to prevent coverage gaps.
B. Channel utilization should be kept under 30 percent:
This guideline specifies that the channel utilization should be kept under 30 percent. Channel utilization refers to the percentage of time that the wireless channel is occupied by data traffic. High channel utilization can lead to increased contention, resulting in lower throughput and increased packet loss, which can negatively impact the voice quality.
C. Noise levels should not exceed -92 dBm:
Noise refers to the unwanted signals or interference that can affect the wireless signal quality. Cisco recommends that the noise level should not exceed -92 dBm. High noise levels can cause packet loss and increase the retransmission rate, which can negatively impact the voice quality.
D. Packet loss should not exceed 5 percent:
Packet loss refers to the percentage of packets that are lost during transmission. Cisco recommends that the packet loss should not exceed 5 percent. High packet loss can cause voice quality degradation, resulting in choppy or garbled voice.
E. Jitter should be kept at a minimum (less than 300 ms):
Jitter refers to the variation in the delay of packets arriving at the destination. Cisco recommends that the jitter should be kept at a minimum, preferably less than 300 ms. High jitter can cause voice quality issues, resulting in delays or interruptions in the voice transmission.
F. 802.11 retransmissions should be less than 20 percent:
802.11 retransmissions refer to the retransmission of packets due to errors or collisions. Cisco recommends that the 802.11 retransmissions should be less than 20 percent. High retransmission rates can cause voice quality issues, resulting in choppy or garbled voice.
In summary, the three guidelines considered Cisco RF guidelines for a proper VoWLAN deployment are: