Hi all,

I'm configuring a Model Serving endpoint with two served entities and ran into some unexpected behavior while testing different traffic_config splits.

When I set traffic_percentage to 100 for each of the two served entities (so the total sums to 200%, not 100%), the configuration is accepted and saves successfully — both through the Serving UI and the REST API. I expected this to be rejected, since traffic percentages across routes should normally sum to 100.

Config used:

"traffic_config": {
  "routes": [
    { "served_model_name": "model-A", "traffic_percentage": 100 },
    { "served_model_name": "model-B", "traffic_percentage": 100 }
  ]
}

What I'm trying to understand:

• Is there backend validation that should reject a traffic_config where the values don't sum to 100? If so, why does this particular config get accepted?
• If it is accepted, how does routing actually work here — are the values treated as relative weights and normalized (e.g., 100/100 effectively becomes 50/50), or is there some other fallback logic?
• Is this documented anywhere, or is it more of an edge case / bug that hasn't been addressed?

I ran a batch of test requests afterward and saw roughly a 50/50 split across the two entities, which lines up with the "weights get normalized" theory — but I'd rather get confirmation from someone who knows the internal routing logic than rely purely on my own testing.

Environment: AWS Databricks