Jitter is the variation in latency between packets. Consistent ms latency is fine. Latency jumping between ms and ms breaks real-time applications.
Why jitter matters:
Voice and video rely on steady packet arrival. Your phone buffers packets to smooth out variation. Too much jitter exceeds buffer capacity. Audio crackles.
Causes of jitter:
- Variable queuing delays
- Route changes
- Competing traffic
- Wireless interference
Acceptable jitter:
- VoIP tolerates up to ms
- Video conferencing allows - ms with buffering
QoS mechanisms reduce jitter by prioritizing sensitive traffic.