ulearn/systems

topics / traffic-routing

Load Balancer

Round robin, least connections, weighted and IP-hash routing across a pool of backends. Break one on purpose and watch the routing decision change.

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0sent
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in flightstalled at backendsuccesserror / rejectedDDoS requestclientsLBround-robinBackend 1healthyconn 0Backend 2healthyconn 0Backend 3healthyconn 0Backend 4healthyconn 0

Event log

Waiting for traffic…

Algorithm

Round robin: Sends each new request to the next backend in a fixed rotation, looping back to the start once it reaches the end. Simple and even when every backend is roughly equal, blind to how loaded each one actually is.

Traffic

Backends

A health check auto-marks a backend downafter repeated failures — “Kill” simulates an outage happening in the first place.

Backend 1
Backend 2
Backend 3
Backend 4