What is a floating IP?

Floating IP – definition

A floating IP is usually a public, routable IP address that is not automatically assigned to an entity. Instead, a project owner assigns them to one or more entities temporarily. The respective entity has an automatically assigned, static IP for communication between instances in a private, non-routable network area, as well as via a manually assigned floating IP. This makes the entity’s services outside a cloud or network recognizable and therefore achievable .

In appropriately configured failover scenarios, an IP ‘floats’ to another active unit in the network so that it can take on the function of a dormant entity without a time delay , and can then answer incoming requests.

How is a floating IP generated?

Users obtain floating IPs for their projects from different pools that the system administrator configures and provides as server resources. As soon as a user receives a floating IP, they become the ’ owner '. They can assign it to an entity, remove it, and then assign it to another at any time. Even if an entity is terminated, the user does not ‘lose’ the associated floating IP. It remains as a resource and can still be assigned to another entity when needed.

A major reason for using several parallel floating IP pools is that each pool can be operated by another internet service provider or can also be assigned by other external networks. This ensures that the connectivity or availability is maintainable even if an internet service provider should fail due to a malfunction.

When are floating IPs used?

Maximum availability is one of the key factors in every production environment. In the communication network, however, a single error can cause applications to fail. Developers do sleep better knowing that their applications are designed to withstand any conceivable error scenarios. The goal is to provide a highly available piece of infrastructure with minimal downtime .

A floating IP can serve as a flexible load balancing address , helping to balance peak loads by distributing incoming network traffic to different network nodes. Network nodes are devices which connect two (or more) transmission paths of a telecommunication network. As with a computer that distributes workflows across multiple processors, load balancing also handles large amounts of simultaneous requests or more complex calculations by splitting the load across multiple parallel systems .

Failover and switchover

If a primary load balancer or a central application server in a cluster fails on one side, a floating IP can be immediately assigned a redundant application server or a secondary load balancer in a correspondingly configured system. The IP ‘floats’ to the active unit , which immediately carries out the desired processes. An unplanned change between network services is referred to as ‘failover’. This kind of protection is especially recommended for critical applications .

A planned change from a primary to a secondary system is referred to as a ‘switchover’. The targeted transmission of services is not triggered by errors, but is usually controlled by a system administrator. A classic reason for a switchover is, for example, routine maintenance of the primary or secondary systems where a parallel instance temporarily takes over its function.

What advantages does a floating IP offer?

One of the main advantages of floating IPs is their flexibility – the free and needs-oriented assignability. Floating IPs are therefore suitable for use in both failover and switchover environments – for example, for performing upgrades of applications or entire sites with minimal downtime. While an upgrade is applied to one entity, another one takes on the traffic. Once the upgrade has been successfully completed, the traffic is redirected to the updated unit.

Another advantage: even if several or even many different entities are concealed behind a service being offered, the floating IP appears on the surface to users (who make use of the service) rather than the server’s IP that offers the respective service.