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Reserved IP Addresses

Last updated on Oct 04, 2025

Overview

Reserved IP addresses (also known as floating IPs) are flexible, re-routable IP addresses that can be dynamically assigned to different virtual machines within your Onidel Cloud infrastructure. Unlike standard IPs that are permanently bound to a specific VM, Reserved IPs can be instantly moved between instances, providing high availability and seamless failover capabilities.

When you provision a Reserved IP, it exists independently of any VM instance. You can attach it to a VM and later reassign it to another VM without changing DNS records or updating client configurations.

Key Benefits

  • You can move the reserved IP address from one VM to another (e.g. during maintenance or in response to failure) through our control panel or API.

  • You can assign one or more Reserved IP addresses to your VM, allowing it to communicate with external systems using multiple public IPs.

  • When you decommission an old VM and provision a new one, you can attach the same Reserved IP. This avoids updating DNS records or client configurations, making migrations frictionless.

  • You can hold on to your favourite IP and use it again later - for any reason you like!

How Reserved IPs Work

A Reserved IP address has a dynamic, one-to-one relationship with an "Anchor" IP address. The Anchor IP is the primary IP address of the VM that the Reserved IP is being routed to.

This sounds complicated, but it simply means that the Reserved IP piggybacks on another IP address, which you can choose and change at your leisure.

Via the Onidel Cloud Control Panel and API, the Reserved IP ↔ Anchor IP relationship can be updated in real-time, allowing you to direct traffic to the VM of your choice.

Example Scenario:

  1. A user enters the Reserved IP address 198.51.100.50 in their browser

  2. This Reserved IP's current Anchor IP is 203.0.113.10, which belongs to VM-A

  3. The user will be served the website running on VM-A

When you change the Anchor IP to 203.0.113.20 (which belongs to VM-B), the same user accessing the same Reserved IP will now be served the website running on VM-B.

This change is instant, without any perceptible downtime from the end user's perspective. Behind the scenes, our infrastructure simply updates the routing table to forward all traffic destined for the Reserved IP to the new Anchor IP.

Use Cases

Unplanned Downtime Recovery

If your primary VM becomes unavailable, instantly redirect traffic to a standby VM by reassigning the Reserved IP. This provides near-zero downtime recovery without DNS propagation delays.

Zero-Downtime Maintenance

Before performing maintenance on your production VM:

  1. Ensure your standby VM is synchronised

  2. Reassign the Reserved IP to the standby VM

  3. Perform maintenance on the primary VM

  4. Optionally reassign the Reserved IP back after maintenance

Provisioning Reserved IPs

Via Control Panel

  1. Navigate to Network → Reserved IPs in your Onidel Cloud dashboard

  2. Click New Reserved IP

  3. Select IP type, your desired location and enter reserved IP name

  4. Click Add Reserved IP

Via API

curl -X POST https://api.cloud.onidel.com/network/reserved-ips \
  -H "Authorization: Token YOUR_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "ip_type": "ipv4",
    "location": "sydney"
  }'

Reference: Reserved IPs - Developer Docs

Pricing

  1. Billing: Hourly billing with a maximum of $3.00/month per /32 IPv4 or $1.00/month per /64 IPv6

  2. Minimum Charge: 24 hours

  3. No bandwidth charges: Uses your VM's allocated bandwidth

Configuring Reserved IPs

Step 1: Configure on Target VMs

Reserved IPs must be configured as secondary IPs on all potential target VMs:

Ubuntu 22.04+ (Netplan):

# Create a new file: /etc/netplan/60-reserved-ip.yaml
network:
  version: 2
  ethernets:
    eth0:
      addresses:
        - YOUR_RESERVED_IP/32

Apply the configuration:

sudo netplan apply

Ubuntu 20.04 and earlier / Debian:

# Add to /etc/network/interfaces
auto eth0:1
iface eth0:1 inet static
    address YOUR_RESERVED_IP
    netmask 255.255.255.255

Apply the configuration:

sudo ifup eth0:1
# Or restart networking service
sudo systemctl restart networking

CentOS/RHEL:

# Create /etc/sysconfig/network-scripts/ifcfg-eth0:1
DEVICE=eth0:1
IPADDR=YOUR_RESERVED_IP
NETMASK=255.255.255.255
ONBOOT=yes

Apply the configuration:

sudo ifup eth0:1
# Or restart network service
sudo systemctl restart network

Step 2: Assign to Anchor IP

Via Control Panel:

  1. Go to Network → Reserved IPs

  2. Click on your Reserved IP

  3. Choose the target VM and click Attach Reserved IP

Via API:

curl -X PUT https://api.cloud.onidel.com/network/reserved-ips/YOUR_RESERVED_UUID \
  -H "Authorization: Token YOUR_API_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "anchor_ip": "TARGET_VM_PRIMARY_IP"
  }'

Reference: Reserved IPs - Developer Docs

Step 3: Verifying Configuration

Test connectivity to ensure the Reserved IP is properly routed:

# From external host
ping YOUR_RESERVED_IP

# From the VM
ip addr show | grep YOUR_RESERVED_IP