Optimizing traffic steering

Load balancing provides several traffic steering modes, which allow customers to optimize how load balancers route traffic.

You can configure traffic steering from the load balancing dashboard, in the Edit Load Balancer panel. You can also configure traffic steering via the CIS API. Available steering options include standard failover (steering disabled), dynamic steering, and geo steering.

Standard failover

Standard failover directs traffic from unhealthy pools to the next healthy pool in the configuration, using the pool order to determine failover priority (the failover order).

If all pools are marked unhealthy, the load balancer directs traffic to the fallback pool. The default fallback pool is the last pool listed in the load balancer configuration.

To nominate a specific fallback pool through the CIS API, use the Update Load Balancers command and set the fallback_pool parameter. If no monitors are attached to the load balancer, it directs traffic to the primary pool exclusively.

Dynamic steering

Dynamic steering uses health check data to identify the fastest pool for a CIS region or point of presence (PoP).

Dynamic steering creates Round Trip Time (RTT) profiles based on an exponential weighted moving average (EWMA) of RTT to determine the fastest pool. If there is no current RTT data for your pool in a region or colocation center, CIS directs traffic to the pools in failover order.

Allow 10 minutes for CIS to build an RTT profile the first time you enable dynamic steering for a server pool.

If you are terminating TCP at a cloud provider edge location, the calculated latency might not reflect the true latency to the origin for TCP health checks.

The following diagram shows how CIS routes traffic to the pool with the lowest EWMA among three regions: Eastern North America, Europe, and Australia. In this case, the ENAM pool is selected, because it has the lowest RTT.

Figure showing traffic steering — Figure 1. Traffic steering in CIS

Geo Steering

Geo steering directs traffic to pools based on the client’s region or PoP. Only domains on Enterprise plans can perform geo steering by PoP. Users specify the pools to which the load balancer directs traffic for a geographical region or PoP. You can assign multiple pools to the same region, and the load balancer uses them in failover order. If there is no configuration for a region or pool, the load balancer uses the default failover order.

Our partners at Cloudflare have 13 geographic regions. The region of a client is determined by the region of the Cloudflare data center that answers the client’s DNS query. These regions are listed in the following table, along with their region codes.

Table 1. Geographic regions and codes
Region Code	Region
WNAM	Western North America
ENAM	Eastern North America
WEU	Western Europe
EEU	Eastern Europe
NSAM	Northern South America
SSAM	Southern South America
OC	Oceania
ME	Middle East
NAF	Northern Africa
SAF	Southern Africa
SAS	Southern Asia
SEAS	Southeast Asia
NEAS	Northeast Asia