What is a floating IP?

A static IP, on the other hand, is a fixed address and is per­ma­nent­ly assigned to a device. Static IP addresses are found mainly in the web server or e-mail server area, or wherever offers or website content must be ac­ces­si­ble via a fixed URL , so that users or processes can (re)find them without any problems. Computers in a network or pe­riph­er­al devices (such as printers) have fixed IPs, so that the in­di­vid­ual devices within the network can easily com­mu­ni­cate with one another.

So that users don’t have to remember complex numbers, it’s possible to assign a domain name to a static IP address e.g. www.example.org. The numerical IP, the 'con­nec­tion number' of a device in the network, is therefore trans­lat­ed into a name that can easily be re­mem­bered. This is generally only reserved for static IPs. It doesn’t make much sense for dynamic IPs since the user changes so fre­quent­ly.

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.

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.

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.

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.

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.