# Floating IP

A **Floating IP** is a public IP address that can quickly move from one server to another. If one server goes down, the Floating IP can switch to a backup server, so your service stays online without interruption.

### Example:

Imagine you have two nodes: **Node A** and **Node B**.

- You attach the same Floating IP to both.
- You set **Node A** as the **master** node with high priority.
- **Node B** is the **backup** node with lower priority.

By default, the Floating IP points to **Node A**.

But if **Node A fails** for any reason, the Floating IP will **automatically switch to Node B**. This happens **without any downtime**.

### Why use it?

This setup helps keep your services **always available**, even if one node goes down. It adds **failover support** and improves **network reliability**.

### How to create a Floating IP and attach to Node?
1. Reserve a Floating IP and attach to the node. For more details [click here](./reserve_ip.mdx#use-reserve-ip-as-floating-ip)

### Commands to configure Floating IP
Below are the commands to set up a Floating IP on your Ubuntu Node using **Keepalived**. Users can use other tools as well.

```bash
#connect to the Node
ssh root@<node_ip>

sudo apt update

#install keepalived
sudo apt install keepalived -y 
```
Now create a config file for keepalived
```bash
cd /etc/keepalived/
touch keepalived.conf
sudo vi keepalived.conf
```
Now for **Master Node** edit the keepalived.conf file to set up the Floating IP. Here is an example configuration:
```bash
vrrp_instance VI_1 {
    state MASTER
    interface ens3                   # Replace with your network interface
    virtual_router_id 51
    priority 100                     # Higher priority means this node is preferred
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        <Floating_IP>
    }
}
```
For **Backup Nodes** , Edit the keepalived.conf file to set up the Floating IP. Here is an example configuration:
```bash
vrrp_instance VI_1 {
    state BACKUP
    interface ens3                  # Replace with your network interface
    virtual_router_id 51
    priority 90                    # Lower priority than MASTER
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        <Floating_IP>
    }
}
```
Now Enable and Start the keepalived
```bash
sudo systemctl enable keepalived
sudo systemctl start keepalived
sudo systemctl status keepalived
```
### Verify the Floating IP
```bash
ip addr show ens3 | grep <Floating_IP>
```



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