How to configure the OVHcloud Load Balancer in multiple zones

Objective

The OVHcloud Load Balancer is a critical component for distributing network traffic across your infrastructure. To ensure the highest level of service and optimal user experience, it is essential to deploy your Load Balancer across multiple availability zones (AZ). When subscribing to an OVHcloud Load Balancer service, you may choose one or more availability zones in which the service will be located. You also have the possibility to order additional zones for an existing service.

Configuring your OVHcloud Load Balancer in multiple availability zones will help you increase the reliability of your Load Balancer service in case a zone is unavailable, or minimize latency for your users by directing the traffic to the service nearest to them.

This guide details how to configure and utilize these multiple zones to achieve enhanced performance and resilience.

Requirements

• An OVHcloud Load Balancer service
• Access to the OVHcloud Control Panel

Introduction to availability zones

Multi-region configuration

Load balancing across multiple regions offers maximum disaster recovery against widespread regional outages and allows for worldwide entry points that significantly reduce latency by routing users to the nearest server. Most regions only have one availability zone, which means that working with several zones usually involves working with several regions.

By leveraging an Anycast network, the OVHcloud Load Balancer can redirect requests coming from a specific region to the geographically nearest backend servers.

To achieve this, you need to specify a frontend in each zone that uses a cluster in the same zone. This will allow you to declare backend servers in different clusters per zone and to control which backend servers are used in which zone.

Diagram representing a load balancer distributing traffic across two regions

For example, if you have backend servers in the Gravelines (GRA) and Beauharnois (BHS) regions, you can order a Load Balancer service in the GRA and BHS zones and configure:

• A frontend in the GRA zone with a default cluster in the GRA zone which contains servers in the Gravelines datacenter.
• A frontend in the BHS zone with a default cluster in the BHS zone that contains servers in the Beauharnois datacenter.

Multi-AZ regions

OVHcloud is currently rolling out its strategic plan for multi-Availability Zone (multi-AZ) regions, beginning with the launch of Paris 3-AZ in April 2024 and Milan 3-AZ in November 2025.

Load balancing across several Availability Zones (AZs) within the same region, in contrast to a multi-region configuration, ensures high availability, high performance and fault tolerance against local outages, using low-latency connections and Anycast to distribute traffic in the most efficient way.

Diagram representing a load balancer distributing traffic across the zones of a single multi-AZ region

Instructions

Add a zone

From the OVHcloud Control Panel

You can order an additional zone from the OVHcloud Control Panel. In the Network section, under Network services, click on Load Balancer.

Select your Load Balancer, then in the Home tab and the Configuration menu, click Add in the "Availability zones" section.

Then select the zone(s) you wish to order and click Add.

A purchase order will be generated, which you'll need to pay.

From the API

To order a zone via the API, you first need to create a cart.

Please make a note of the cart ID ("cart"), it will be useful later in the ordering process.

Then, assign the cart to your OVHcloud account via the following call:

You can list the options available on your Load Balancer service via the following call:

When you have found the option corresponding to the desired area, you can add it to your shopping cart ("cart") via the following call:

Finally, you can validate your cart ("cart") via the following call:

Don't forget to pay the order form thus generated.

Configure your frontend

Once your zone order is finalized, you can add it to your Load Balancer from the OVHcloud Control Panel.

Select the Load Balancer you wish to modify, then create a new frontend, or edit an existing one, via the Frontends tab.

In the Datacenter field, choose the zone you wish to associate with your frontend.

If you want to use multiple zones, you can choose the special ALL zone. This special zone will allow you to deploy the same configuration on all zones subscribed to your Load Balancer service, which spares you having to duplicate the configuration for all zones.

Once the frontend is configured, click Add or Modify depending on whether you are configuring a new frontend or an existing one.

Don't forget to deploy the configuration. To do this, click Apply configuration in the reminder banner stating that the configuration is not applied.

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