QoS must be monitored continuously. Configuration alone does not guarantee results.
Metrics to monitor:
- Queue depths and drop rates
- End-to-end latency per class
- Jitter variation over time
- Throughput per class
Verification methods:
Interface statistics. Queue depths, drops, bandwidth per class.
IP SLA probes. Generate traffic. Measure latency, jitter, loss.
Packet captures. Verify DSCP at each hop.
Red flags:
- Priority queue dropping (misconfigured policing)
- High latency despite low utilization (wrong queue)
- Best effort completely starving