What is LLM router?
An LLM router automatically directs each request to an appropriate model or backend based on availability, cost, capability, or a routing rule.
Routing is the decision layer inside a gateway. At minimum it maps a requested model to a backend that can serve it. More advanced routers pick a model dynamically — by task, by cost ceiling, or by which backend is currently healthy — and fall back to an equivalent model when the first choice fails.
Good routing is invisible: your request succeeds even when an individual backend is degraded, and you don't have to write retry-and-fallback logic yourself. Routing also enables aliases — stable names like 'best' or 'fast' that resolve to whatever concrete model is currently the right pick.
How Kyma does it
Kyma routes every request through a multi-layer never-die chain: retry, then an equivalent model, then a parallel race across quality-tier peers, so a single upstream outage doesn't surface as an error. Aliases such as best, fast, code, and cheap resolve to the current best model automatically.