Which three features are properties and one-way requirements for voice traffic? (Choose three.)
- The required bandwidth is roughly between 30 and 128 kbps.
- The required bandwidth is roughly between 0.5 and 20 Mbps.
- Latency should be below 400 ms.
- Latency should be below 150 ms.
- Voice traffic is smooth.
- Voice traffic is bursty.
Explanation: Voice traffic is smooth: According to the sources, voice traffic is categorized as real-time traffic that comprises constant and predictable bandwidth and packet arrival times. This "predictable" nature defines the traffic as smooth, as opposed to data traffic which is characterized as bursty and unpredictable.
Latency should be below 150 ms: Voice is extremely time-critical. While the sources note that interactive video shares the same delay and jitter requirements as voice, they emphasize that timely delivery of data is crucial and that real-time applications do not retransmit lost data. To maintain the quality of a two-way conversation, the industry-standard one-way latency requirement is 150 ms or less. (Note: While snippet mentions a 150 ms switchover time for high availability, the 150 ms latency requirement for voice is a standard networking principle used to ensure transmission quality).
Required bandwidth (30–128 kbps): The sources mention that voice packets are generally small compared to video packets. Because voice uses constant bit-rate codecs, its bandwidth requirement is relatively low and stable, typically ranging between 30 and 128 kbps depending on the specific codec and header overhead used. By contrast, video traffic requires significantly higher bandwidth, often in the Mbps range.
Related exam: Modules 1 – 7: Checkpoint Exam: Network Switching Answers (CCNP ENCOR v9)
