​​ Least Outstanding Request steering

Least Outstanding Request Steering allows you to route traffic to pools or origin servers that currently have the lowest amount of outstanding requests. The origin weights are scaled proportionally by the ratio of active connections.

During instances in which you have a large difference between the size of requests or time to process them, Least Outstanding Request Steering ensures that traffic is evenly distributed, preventing legitimate customer traffic from taking down specific servers. It works at the pool and origin level, and takes into account the pool’s health status, adaptive routing, and session affinity.

Least Outstanding Request Steering selects a pool by taking into consideration random_steering weights, as well as each pool’s number of outstanding requests. Pools with more pending requests are weighted proportionately less in relation to others.

​​ Configure via the API

Load Balancers
{
 "steering_policy": "least_outstanding_requests"
}

Refer to the API documentation for more information on the load balancer configuration.

Pools
{
  "origin_steering": {
     "policy": "least_outstanding_requests"
    }
}

Refer to the API documentation for more information on the pool configuration.

​​ Limitations

Least Outstanding Request Steering supports DNS-only load balancers, but in a no-operation, dummy form. This will allow all counters acting as zero to serve traffic according to the origin weight.

Although it is still supported, it is not recommended to use Least Outstanding Request Steering for DNS-only load balancers since Cloudflare will always consider outstanding requests to be zero.