Traffic allocation is the percentage of traffic that is evaluated against the targeting and default rules. If you allocate 75% of your traffic to be eligible for evaluation, 25% of the traffic is not evaluated by the targeting and default rules and is shown the default treatment with the applied rule not in split.
Use traffic allocation to control the customers exposed to different feature treatments, and increase the number of customers in the split without moving customers in your experiment across treatments.
In this example, we can start by only including 10% of our traffic in the split, while doing a 20-80 split on the included traffic. We can increase traffic allocation to increase exposure, by increasing the traffic included in the split, without changing the 20-80 split. As a result, customers who were seeing the on and off treatments continue to have the same experience while new customers are added to the evaluation.
By default, split allocates 100% of traffic to be evaluated against the targeting and default rules.