What Is Jitter?
Jitter — the variation in delay between packets arriving — even if average latency is fine, jitter makes packets arrive unevenly, which is especially damaging for real-time audio and video.
How it works
If packets normally take 20ms but sometimes take 15ms and other times 40ms, that inconsistency is jitter. Voice and video calls buffer incoming packets briefly to smooth this out — but too much jitter overwhelms the buffer, causing choppy audio or frozen video frames.
Why it matters
Jitter is a key QoS metric alongside latency and packet loss — VoIP and video conferencing are far more sensitive to jitter than to raw bandwidth. Cisco QoS mechanisms prioritise real-time traffic specifically to minimise it.
Frequently asked questions
What is jitter in networking?
The variation in delay between arriving packets — inconsistent timing, as opposed to latency which measures the average delay itself.
Why does jitter affect video calls more than downloads?
Real-time media needs packets to arrive at a steady rate for smooth playback; a file download just needs all the data eventually, so timing variation doesn't matter as much.
How is jitter reduced?
QoS prioritisation for real-time traffic, sufficient bandwidth headroom, and jitter buffers on receiving devices that smooth out small timing variations.
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