Quality of Service
Techniques that prioritize critical traffic, such as voice and video, over less time-sensitive data.
Quality of Service (QoS) is a set of traffic-management mechanisms that protect bandwidth and reduce latency and jitter for time-sensitive applications such as VoIP, video conferencing, and streaming. It classifies packets and marks them with priority values—DSCP in the IP header or 802.1p priority bits inside the 802.1Q Layer 2 tag—then applies queuing and scheduling so high-priority traffic forwards first. For the exam, note that traffic shaping (one QoS tool) delays excess traffic to smooth bursts, while QoS overall assigns relative priority between traffic classes; know which mechanism targets latency versus bandwidth exhaustion.
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