---
title: "Set up failover with a Floating IP"
description: "Keep a service reachable when a node fails, by attaching a Floating IP to a primary node and a backup and configuring failover."
content_type: "how-to"
product: "reserved-ip"
platform: "MyAccount"
url: "/myaccount/reserved-ip/how-to/set-up-failover-with-a-floating-ip/"
topic: ["floating"]
relationships: {"requires":["/myaccount/reserved-ip/how-to/use-a-reserved-ip-as-a-floating-ip/"]}
---

# Set up failover with a Floating IP

With a Floating IP on two nodes, you can keep a service reachable when one of them fails. One
node holds the address; the other watches it and takes the address over when the first one
stops. The steps set that up on two Ubuntu nodes with Keepalived, an open-source tool commonly used for this. Other tools that move an address between machines work on the same idea.

## Before you begin

- A [Floating IP](/myaccount/reserved-ip/how-to/use-a-reserved-ip-as-a-floating-ip/) attached
  to both nodes.
- The same service running on both nodes, so either one can answer.
- SSH access to both nodes as `root`.

## Set up the primary node

1. Connect to the primary node over SSH and install Keepalived:

   ```bash
   apt update
   apt install keepalived -y
   ```

2. Create `/etc/keepalived/keepalived.conf` with this content:

   ```text
   vrrp_instance VI_1 {
       state MASTER
       interface ens3
       virtual_router_id 51
       priority 100
       authentication {
           auth_type PASS
           auth_pass <password>
       }
       virtual_ipaddress {
           <floating-ip>
       }
   }
   ```

   Put your Floating IP in place of `<floating-ip>`. Put a password of your own in place of
   `<password>`; Keepalived reads its first eight characters. `ens3` is the public network
   interface on Ubuntu 24.04 nodes, and `ip addr` shows the name on yours.

3. Start Keepalived, now and at every boot:

   ```bash
   systemctl enable --now keepalived
   ```

   Within a few seconds the primary claims the Floating IP, and your service answers on it.

## Set up the backup node

1. Connect to the backup node and install Keepalived the same way.
2. Create `/etc/keepalived/keepalived.conf` with the same content and two changes: `state` is
   `BACKUP`, and `priority` is lower than the primary's.

   ```text
   vrrp_instance VI_1 {
       state BACKUP
       interface ens3
       virtual_router_id 51
       priority 90
       authentication {
           auth_type PASS
           auth_pass <password>
       }
       virtual_ipaddress {
           <floating-ip>
       }
   }
   ```

   Keep the virtual router id, `51` here, and the password the same as on the primary. That is
   how the two nodes know they are a pair.

3. Start Keepalived:

   ```bash
   systemctl enable --now keepalived
   ```

## Test the failover

On the primary, check that it holds the address:

```bash
ip addr show ens3 | grep <floating-ip>
```

Now stop Keepalived on the primary to act out a failure:

```bash
systemctl stop keepalived
```

Run the same `ip addr` command on the backup: within a second or two the Floating IP is
there, and your service still answers on it. Start Keepalived on the primary again with
`systemctl start keepalived`, and with its higher priority it takes the address back.

Your service now stays on one address through a node failure. For a third or fourth node,
attach it to the Floating IP and give it the backup configuration with a lower priority again;
see [Use a reserved IP as a Floating IP](/myaccount/reserved-ip/how-to/use-a-reserved-ip-as-a-floating-ip/#add-or-remove-nodes).