ADC Traffic Split Calculator
Plan a canary traffic split on the load balancer: canary load, capacity headroom, error-rate delta and whether to widen or roll back.
Inputs
Request Rate to the Canary
400.0rps
Request Rate to the Stable Pool
7,600.0rps
Canary Pool Utilisation
66.7%
Maximum Weight the Canary Can Absorb
7.5%
Error-Rate Delta vs Stable
0.60percentage points
Errors Observed in the Window
5,760
Release Decision
Roll back — the canary is more than 0.5 points worse than stable
Step by step
Values used
Total request rate = 8,000 rps; Weight routed to the canary = 5 %; Canary pool capacity = 600 rps; Canary error rate = 0.8000 %; Stable error rate = 0.2000 %; Observation window = 30 minutes
ADC Traffic Split
canary rate = total rate × weight; maximum safe weight = canary capacity ÷ total rate; error delta = canary error rate − stable error rate.
Request Rate to the Canary
= 400.0 rps
Request Rate to the Stable Pool
= 7,600.0 rps
Canary Pool Utilisation
= 66.7
Maximum Weight the Canary Can Absorb
= 7.5
Error-Rate Delta vs Stable
= 0.60 percentage points
Errors Observed in the Window
= 5,760
How it works
The split is a weighted distribution, so the canary receives the weight times the total rate and must have the capacity to serve it. Comparing the canary's error rate to the stable pool over a fixed window turns the split into a pass/fail signal, with the sample size shown so you can judge whether the difference is meaningful. Most canary rollbacks are triggered by a canary pool that was simply too small for its weight, so separating a capacity problem from a code problem is the whole point of checking utilisation alongside the error delta.
Formula
ADC Traffic Split
canary rate = total rate × weight; maximum safe weight = canary capacity ÷ total rate; error delta = canary error rate − stable error rate.
- share
- Fraction of traffic the load balancer sends to the new version
- errorDelta
- Difference in percentage points, the signal a canary exists to produce
Frequently Asked Questions
How is ADC Traffic Split calculated?
canary rate = total rate × weight; maximum safe weight = canary capacity ÷ total rate; error delta = canary error rate − stable error rate. The split is a weighted distribution, so the canary receives the weight times the total rate and must have the capacity to serve it. Comparing the canary's error rate to the stable pool over a fixed window turns the split into a pass/fail signal, with the sample size shown so you can judge whether the difference is meaningful.
Why does ADC Traffic Split matter?
Most canary rollbacks are triggered by a canary pool that was simply too small for its weight, so separating a capacity problem from a code problem is the whole point of checking utilisation alongside the error delta.
What values do I need to enter?
This calculator takes 6 inputs: Total request rate, Weight routed to the canary, Canary pool capacity, Canary error rate, Stable error rate, Observation window. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
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