Which of the following does Cisco recommend as the maximum amount of packet loss on a VoIP network?
(Select the best answer.)

A.
1 percent

B.
3 percent

C.
20 percent

D.
50 percent

Explanation:
Cisco recommends a maximum packet loss of 1 percent for Voice over IP (VoIP) traffic. Packet loss is often
caused when networks become congested and packets are dropped. Dropped packets can cause clips, or
breaks, in the audio stream. However, voice traffic is more tolerant of dropped packets than of delayed packets
because a small amount of packet loss is not noticeable to the human ear. Some codecs can correct small
amounts of packet loss. On networks with limited bandwidth, a lowbitrate codec can mitigate packet loss.
However, the overall quality of the audio will be reduced. Packet loss can also be mitigated by implementing
Quality of Service (QoS) mechanisms.
Short delays and low packet loss on a VoIP network help protect the rate at which bits flow over the network. In
addition to the packet loss recommendations, Cisco recommends a maximum jitter of 30 ms for VoIP traffic.
Jitter is a variation in delay, which can cause voice traffic to arrive at different times, thereby causing breaks, or
choppiness, in the audio stream. Jitter can be mitigated by implementing QoS mechanisms.
Cisco also recommends a maximum endtoend delay of 200 ms. The International Telecommunication Union
(ITU) considers an endtoend delay of 150 ms or less to be acceptable for high voice quality. Delay, which is
also called latency, can introduce interruptions in conversation flow, causing the speakers at each end of the
circuit to interrupt each other. Endtoend delay can be mitigated by implementing QoS mechanisms.

https://www.cisco.com/c/en/us/td/docs/ios/solutions_docs/qos_solutions/QoSVoIP/QoSVoIP.pdf