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Introducing Spectrum with Load Balancing


4 min read

We’re excited to announce the full integration of Cloudflare Spectrum with Load Balancing. Combining Spectrum with Load Balancing enables traffic management of TCP connections utilising the same battle tested Load Balancer our customers already use for billions of HTTP requests every day.

Customers can configure load balancers with TCP health checks, failover, and steering policies to dictate where traffic should flow. This is live in the Cloudflare dashboard and API — give it a shot!

TCP Health Checks

You can now configure Cloudflare’s Load Balancer health checks to probe any TCP port for an accepted connection. This is in addition to the existing HTTP and HTTPS options.

Health checks are an optional feature within Cloudflare’s Load Balancing product. Without health checks, the Cloudflare Load Balancer will distribute traffic to all origins in the first pool. While this is in itself useful, adding a health check to a Load Balancer provides additional functionality.

With a health check configured for a pool in a Load Balancer, Cloudflare will automatically distribute traffic within a pool to any origins that are marked up by the health check. Unhealthy origins will be dropped automatically. This allows for intelligent failover both within a pool and amongst pools. Health checks can be configured from multiple regions (and even all of Cloudflare’s PoPs as an Enterprise customer) to detect local and global connectivity issues from your origins.

In this example, we will configure a TCP health check for an application running on port 2408 with a refresh rate of every 30 seconds via either the dashboard or our API.

Configuring a TCP health check

# POST accounts/:account_identifier/load_balancers/monitors

  "description": "Spectrum Health Check",
  "type": "tcp",
  "port": 2048,
  "interval": 30,
  "retries": 2,
  "timeout": 5,
  "method": "connection_established",


Origin weights are beneficial should you have origins that are not of equal capacity or if you want to unequally split traffic for any other reason.

Weights configured within a load balancer pool will be honored with transport load balancing through Spectrum. If configured, Cloudflare will distribute traffic amongst the available origins within a pool according to the relative weights assigned to each origin.

For further information on weighted steering, see the knowledge base article.

Steering Modes

All steering modes are available for transport load balancing through Spectrum: You can choose standard failover, dynamic steering, or geo steering:

  • Failover
    In this mode, the Cloudflare Load Balancer will fail over amongst pools listed in a given load balancer configuration as they are marked down by health checks. If all pools are marked down, Cloudflare will send traffic to the fallback pool. The fallback pool is the last pool in the list in the dashboard or specifically nominated via a parameter in the API. If no health checks are configured, Cloudflare will send to the primary pool exclusively.
  • Dynamic Steering
    Dynamic steering was recently introduced by Cloudflare as a way of directing traffic to the fastest pool for a given user. In this mode, the Cloudflare load balancer will select the fastest pool for the given Cloudflare Region or PoP (ENT only) through health check data. If there is no health check data for a given colo or region, the load balancer will select a pool in failover order. It is important to note that with TCP health checks, latency calculated may not be representative of true latency to origin if you are terminating TCP at a cloud provider edge location.
  • Geo Steering
    Geo Steering allows you to specify pools for a given Region or PoP (ENT only). In this configuration, Cloudflare will direct traffic from specified Cloudflare locations to configured pools. You may configure multiple pools, and the load balancer will use them in failover order. If this steering mode is selected and there is no configuration for a region or pool, the load balancer will use the default failover order.

Build Scalable TCP Applications

Once your load balancer is configured, it’s available for use as an origin with your Spectrum application:

Configuring a Spectrum application with Load Balancing

Combining Spectrum’s ability to proxy TCP applications, our Load Balancer’s full feature set, and Cloudflare’s global network allows our customers to build performant, reliable, and secure network applications with minimal effort.

We’ve seen customers combine Spectrum and Load Balancing to build scalable gaming platforms, make their live streaming infrastructure more robust, push the envelope with interesting cryptocurrency use cases, and lots more. What will you build?

Spectrum with Load Balancing is available to all current Spectrum and Load Balancing users. Want access to Spectrum? Get in touch with our team. Spectrum is available for applications on the Enterprise plan.

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Rustam Lalkaka|@lalkaka
Sergi Isasi|@sgisasi

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