Problems / LLM serving, medium

Provider outage at peak

At 15 s the only model provider goes down for 15 seconds, at 30 chats a second.

Free to open. Runs in your browser, no sign-up.

Your goals

Success ≥ 99% through the outage.

The traffic

30 requests a second for 30 seconds: 100% request (reads).

The system

What each component does in this design, and what calls it. The simulator mimics each one from these settings.

ComponentIts job hereSettings
Load balancerLoad balancerTraffic enters here.Calls AI app.Layer 4 balancers route by IP and port; layer 7 balancers read HTTP and can route by path or header.–
AI appApp serviceLoad balancer forwards to it.Calls Model.Little's law: throughput ≈ concurrency ÷ latency. 200 slots at 50 ms serve about 4,000 req/s.3 replicas × 500 slots · timeout 30 s
ModelLLM endpointAI app calls it.Latency has two parts: time to the first token, then a steady stream of tokens per second.400 streams

Hints

Try it first. Open one hint at a time if you get stuck.

Hint 1

Nothing you run is overloaded.

Hint 2

Gateways fail over to a second provider.

One way to solve it

Add a fallback model from another provider.

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