Graphic: chapter prerequisites for anynode TechNote "High Availability with Floating IP".

Prerequisites

Prerequisites for Starting

Before getting started, there are a few things that should be in place:

  1. Two existing anynode installations: Ensure that you have two anynode instances already installed.

  2. Network visibility: The anynode instances must be able to see each other within the network.

  3. Web Server Connectors Configuration: The web server connectors used for the frontend must be set to a fixed IP address and should not be set to the interface address, if the floating IP address is lower than the fixed IP addresses of the systems.

  4. Floating IP Address: A third IP address must be available that can be dynamically assigned to either system. This is referred to as the floating IP address.

  5. High Availability License: A High Availability (HA) license is required for the second system.

  6. Static IP Addresses for Each System: Each system needs its own statically assigned IP address. This can either be set directly on the system as a static IP or assigned via DHCP.

  7. Resource Scheduler Settings: Resource schedulers like VMware DRS or Proxmox CRS should not be enabled for the machines being used. This can cause timing issues in real-time systems, as the instances might no longer run in sync.

This ensures that all necessary preparations are completed to avoid issues during the configuration process.

What is a Floating IP Address?

A floating IP is a third IP address that is available for the machines in use. This means that the active system "claims" the IP address as soon as it becomes active by sending an ARP announcement across the network, signaling that this system is now the one associated with that IP address.

It is crucial to ensure that this IP address is allowed within the network infrastructure so that the anynode systems can claim the floating IP for themselves.

The assignment of the IP address per system is configured within anynode in the Network Interfaces settings. More details on this will follow later in the TechNote.