Traffic Policing Calculator
Split offered traffic into conforming, exceeding and violating rates for a two-rate three-colour policer.
Inputs
Traffic Dropped (Red)
33.33%
Conforming (Green)
50.00Mbps
Exceeding (Yellow)
30.00Mbps
Violating (Red)
40.00Mbps
Conforming Share
41.67%
CBS Burst Tolerance
10.240ms
EBS Burst Tolerance
6.400ms
Step by step
Values used
Offered rate = 120 Mbps; Committed rate (CIR) = 50 Mbps; Peak rate (PIR) = 80 Mbps; Committed burst size (CBS) = 64 KB; Excess burst size (EBS) = 64 KB
Traffic Policing
green = min(offered, CIR); yellow = min(offered − CIR, PIR − CIR); red = offered − PIR; burst tolerance ms = burst size in bits ÷ the matching rate.
Traffic Dropped (Red)
= 33.33
Conforming (Green)
= 50.00 Mbps
Exceeding (Yellow)
= 30.00 Mbps
Violating (Red)
= 40.00 Mbps
Conforming Share
= 41.67
CBS Burst Tolerance
= 10.240 ms
How it works
A two-rate three-colour policer runs two token buckets. Traffic up to CIR is green, traffic between CIR and PIR is yellow and re-marked for early discard, and anything beyond PIR is dropped immediately. Burst tolerance is simply how long the committed bucket can cover the excess. Unlike a shaper, a policer drops rather than buffers, so an undersized CBS turns normal TCP burstiness into visible packet loss even when the average rate is well under contract.
Formula
Traffic Policing
green = min(offered, CIR); yellow = min(offered − CIR, PIR − CIR); red = offered − PIR; burst tolerance ms = burst size in bits ÷ the matching rate.
- CIR
- Committed rate marked green and always forwarded
- PIR
- Peak rate above which packets are dropped outright
- CBS
- Bucket depth that absorbs short bursts without marking
Frequently Asked Questions
How is Traffic Policing calculated?
green = min(offered, CIR); yellow = min(offered − CIR, PIR − CIR); red = offered − PIR; burst tolerance ms = burst size in bits ÷ the matching rate. A two-rate three-colour policer runs two token buckets. Traffic up to CIR is green, traffic between CIR and PIR is yellow and re-marked for early discard, and anything beyond PIR is dropped immediately. Burst tolerance is simply how long the committed bucket can cover the excess.
Why does Traffic Policing matter?
Unlike a shaper, a policer drops rather than buffers, so an undersized CBS turns normal TCP burstiness into visible packet loss even when the average rate is well under contract.
What values do I need to enter?
This calculator takes 5 inputs: Offered rate, Committed rate (CIR), Peak rate (PIR), Committed burst size (CBS), Excess burst size (EBS). The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.