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Origin steering

Use origin steering to customize how each pool distributes traffic to its associated origins.

These distributions are the result of your origin steering policy combined with the weights assigned to each origin.

Origin steering options

When you create a pool, you have to choose an option for Origin Steering:

  • Random: Sends requests to origins purely based on origin weights. Distributes traffic more accurately, but may cause requests from the same IP to hit different origins.
  • Hash: Cloudflare sends requests to origins based on a combination of origin weights and previous requests from that IP address. Ensures requests from the same IP address will hit the same origin, but actual traffic distribution may differ from origin weights.

Weights

By default, all origins within a pool have a weight of 1.

If you leave each origin with the default setting and choose a Random origin steering policy, each pool will receive the same percentage of traffic. If you were to use a Hash policy, that percentage will vary based on the IP distribution of your requests.

Customize weights

To customize weights when you create or edit a pool, set the Weight to a number between 0 and 1 (expressed in increments of .01). Cloudflare will then send traffic to that pool based on a combination of your origin steering policy and the following formula.

% of traffic to origin = origin weight ÷ sum of all weights in the pool
Origin weight example

Here’s an example applying weights to three origin servers with a Random origin steering policy:

  • Weights: Origin Server A = 0.25; Origin Server B = 0.25; Origin Server C = 0.50
  • When all origins are healthy, each origin will receive the following proportion of total traffic: A = 25%; B = 25%; C = 50%.
  • When one origin is unhealthy (such as origin C), each healthy origin will receive the following proportion of total traffic: A = 50%; B=50%.

A significant amount of traffic is required for the distribution to converge on the expected values.

An origin with a weight of 0 should not receive any traffic sent to that pool (though the origin will still receive health checks).

You can also see this value in the Percent field when creating or editing a pool in the dashboard.

Limitations

If you choose Hash for your Origin Steering or enable session affinity, these options can affect traffic distribution.

Additionally, session affinity takes precedence over any selected weight or origin steering policy.

When using DNS-only load balancing, DNS resolves may cache resolved IPs for clients and affect traffic distribution.