Characteristics of Jitter Buffers | CCIE Collaboration Exam (400-051) | Cisco

Characteristics of Jitter Buffers

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Which two are characteristics of jitter buffers? (Choose two.)



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A. B. C. D. E.


Jitter buffers are used to remove the effects of jitter so that asynchronous packet arrivals are changed to a synchronous stream.

The jitter buffer trades off between delay and the probability of interrupted playout because of late packets (discard)


Jitter buffers are an essential component of real-time communication systems such as Voice over IP (VoIP) and video conferencing. Their primary function is to minimize the effects of jitter, which is the variation in the delay of packets as they traverse a network.

Option A is correct. Jitter buffers are used at the destination end systems to change asynchronous packet arrivals into a synchronous stream by turning variable network delays into constant delays. In other words, packets that arrive with varying delays are collected and temporarily stored in the jitter buffer, which then outputs the packets at a constant rate to the destination device. This process effectively removes the effects of jitter, ensuring that the audio or video stream is delivered smoothly.

Option C is also correct. The role of the jitter buffer is to balance the delay and the probability of interrupted playout due to late packets. Delay refers to the amount of time it takes for a packet to travel from the source to the destination, while interrupted playout refers to the disruption in audio or video playback caused by late or missing packets. The jitter buffer adjusts its delay to strike a balance between minimizing the probability of interrupted playout and keeping the delay within acceptable limits.

Option B is incorrect. Jitter buffers are not used at the sending systems to change asynchronous packet arrivals into a synchronous stream. The sending system typically sends packets as they become available, and it is the responsibility of the receiving system to collect and reorder the packets as necessary.

Option D is partially correct. The role of the jitter buffer is indeed to queue late packets and reorder out-of-order packets. However, it does not just queue all late packets without consideration of their timing. Instead, it selectively queues packets that arrive outside of the expected window and reorder them as needed.

Option E is incorrect. Jitter buffers do not queue packets into constant delays at the sending systems. They are used at the receiving systems to collect and process packets that have already been sent.