Configuring an Additional IP block in a vRack

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This guide will show you how to configure a block of public IP addresses for use with the vRack.

Objective

As well as private IP addressing, the vRack also allows you to route public IP traffic through your server's vRack port using a public IP address block.

This guide will show you how to configure a block of public IP addresses for use with the vRack.

Info

vRack supports both IPv4 and IPv6 public routing with Additional IP address blocks. You can find the instructions on how to configure IPv6 blocks in this guide: "Configuring an IPv6 block in a vRack".

Info

This article is focusing on Additional IP configuration over a vRack network. If you look for guidance on Additional IP configuration together with primary IP (on public network interface), read the following articles:

Requirements

  • A public block of IP addresses in your account, with a minimum of four addresses
  • Your chosen private IP address range
  • A vRack compatible server
  • A vRack service activated in your account

OVHcloud Control Panel Access

  • Direct link:
  • Navigation path: Network > vRack private network
Warning

This feature might be unavailable or limited on servers of the Eco product line.

Please visit our comparison page for more information.

Instructions

Info

For example purposes we'll be using an IP block of 46.105.135.96/28 and eth1 for the secondary network interface, which is dedicated to the vRack.

Also for example purposes, the network configuration file we refer to is located in /etc/network/interfaces. The equivalent file on your server may be located somewhere else, depending on your operating system. The file content may also be different. If you encounter any difficulties, please refer to the official documentation for your distribution.

Add the IP block to the vRack

Warning

Once an IP block is added to the vRack, it is no longer attached to a physical server.

This setup allows you to configure IPs of the same block on multiple servers, provided that these servers are all in the same vRack as the IP block. The IP block must have at least 2 usable IPs or more for this to be possible.

Select your vRack from the list to display the list of eligible services. Click the IP block you wish to add to the vRack and click on the Add button.

Add an IP block to the vRack

Managing public IP bandwidth on vRack

By default, Additional IP blocks routed via a vRack benefit from a standard public bandwidth of 5 Gbps in Europe/Canada/US and 100 Mbps in APAC regions. For a detailed overview of availability, please refer to public routing options on our vRack product page.

As infrastructure requirements scale, users may require broader bandwidth to support high-traffic public-oriented services, for which OVHcloud provides paid bandwidth options. It is important to note that bandwidth options are applied per-vRack and per-region. Since Additional IP addresses are tied to a region, any bandwidth modification will affect all IP addresses (both IPv4 and IPv6) routed to the specific vRack within that particular region.

During the Additional IP ordering process

Choosing public bandwidth during an Additional IP order

The default public bandwidth can be changed when ordering a new Additional IP block with a vRack network as the backend.

To order a new Additional IP block:

  • Open the Network section in the left-hand sidebar.
  • Select Public IP addresses.
  • Click on the Order IPs button, near the top of the page.
  • Select the IP version, then the vRack you want to attach your Additional IP to.
  • Select the region you want your Additional IP to be in.
  • Choose the public bandwidth you want to apply to your vRack for that specific region.
  • Fill in the other options as necessary, then proceed with your order.
From the vRack management page

Modifying vRack public bandwidth on management page

For Additional IP blocks already attached to a vRack, bandwidth can be managed directly through the service configuration page.

To access the management interface:

  • In the "Public IP & bandwidth" column, click the Manage button for the corresponding vRack.

The management page is organized into two tabs:

  • All attached services: For the time being, it redirects to the classic vRack management page. Soon, it will list all the products (Servers, Cloud Projects, etc.) currently linked to the vRack, in a new way.
  • Public IP routing: Manages the public IP routing options of your vRack, including public bandwidth.

To modify the public bandwidth:

  • Navigate to the Public IP routing tab.
  • The interface displays individual management windows for each region (e.g., eu-west-par) associated with the vRack, listing all IP addresses attached to that specific region.
  • Within the window for the relevant region, click the Modify bandwidth button.
  • Select the desired bandwidth option in the panel that appears on the right-hand side, then click Proceed to order to validate the order.
  • Once paid, the selected bandwidth should be available to your vRack in the chosen region after a few minutes.
Info

Charges for the initial month are pro-rated based on the remaining days, with the full rate effective the next billing cycle.

The selected bandwidth upgrade will apply to all IP addresses in that region for the chosen vRack.

Managing 3-AZ failover priorities

Some OVHcloud regions span three Availability Zones (AZs) hosted in physically independent locations within the same region. When such a region is involved in your vRack public IP routing, it is identified in the OVHcloud Control Panel by a 3-AZ badge displayed next to the region name in the Public IP routing tab.

Info

If a region transitioned to 3-AZ while you already had IPs routed via the vRack in that region, those IPs will remain in 1-AZ mode and will not automatically benefit from the 3-AZ routing configuration.

To enable 3-AZ mode for IP blocks routed via the vRack in such regions, remove the IP block from the vRack, then re-add it.

IP blocks that are still routed in 1-AZ mode are identified by a grey 1-AZ badge.

Benefits

  • Built-in resilience: public IP traffic routed via the vRack remains available if a single Availability Zone becomes unavailable, as routing automatically fails over to the next AZ in the priority order.
  • Predictable failover behaviour: each 3-AZ region gives your vRack a Primary Availability Zone and two ordered failover positions, making the failover sequence deterministic.
  • Workload alignment: when other OVHcloud services are deployed in the same 3-AZ region, priorities can be aligned so that the vRack's active AZ matches the AZ hosting your services. This keeps your public traffic in the same AZ as your workload during normal operation.

Mechanics and priority management

When a vRack is first associated with a 3-AZ region, OVHcloud assigns a random priority order to its availability zones. The Primary, Secondary, and Last resort zones are displayed in order of priority in the corresponding region tile on the Public IP routing tab, within the 3-AZ failover priorities subsection, right above a Configure button.

You can override this random assignment at any time, for example to align failover priorities with the AZ layout of other components attached to your infrastructure.

Modify the Availability Zone priorities

To adjust the failover priorities of a 3-AZ region:

  • Open Network in the left-hand sidebar of your Control Panel.
  • Select vRack private network.
  • In the "Public IP & bandwidth" column, click the Manage button for the corresponding vRack.
  • Open the Public IP routing tab.
  • Locate the tile of the 3-AZ region you want to configure, then the 3-AZ failover priorities subsection, and click Configure.
  • In the panel that opens, assign each Availability Zone to one of the three slots: Primary Zone, Secondary Zone and Last resort Zone.
  • Confirm your selection.
Info

Priority changes apply to all Additional IP blocks routed to the corresponding 3-AZ region for the selected vRack, regardless of their IP version.

Configure a usable IP address

For vRack purposes, the first, penultimate, and last addresses in any given IP block are always reserved for the network address, network gateway, and network broadcast respectively. This means that the first useable address is the second address in the block, as shown below:

46.105.135.96   Reserved: Network address
46.105.135.97   First usable IP
46.105.135.98
46.105.135.99
46.105.135.100
46.105.135.101
46.105.135.102
46.105.135.103
46.105.135.104
46.105.135.105
46.105.135.106
46.105.135.107
46.105.135.108
46.105.135.109  Last usable IP
46.105.135.110  Reserved: Network gateway
46.105.135.111  Reserved: Network broadcast

To configure the first usable IP address, we need to edit the network configuration file, as shown below. In this example, we need to use a subnet mask of 255.255.255.240.

Info

The subnet mask we've used in our example is appropriate for our IP block. Your subnet mask may differ depending on the size of your block. When you purchase your IP block, you'll receive an email that will tell you which subnet mask to use.

Download the iproute2 package

Before you begin, download and install iproute2, a package for manual IP routing configuration. This package may already be available on your server — if so, skip to the next step.

Establish an SSH connection to your server and run the following command from the command line. This will download and install iproute2.

# apt-get install iproute2

Next, we need to create a new IP route for the vRack. We'll be adding a new traffic rule by amending the file, as shown below:

/etc/iproute2/rt_tables

#
# reserved values
#
255	local
254	main
253	default
0	unspec
#
# local
#
#1	inr.ruhep
1 vrack

Amend the network configuration file

Info

For example purposes, the network configuration file we refer to is located in /etc/network/interfaces. The equivalent file on your server may be located somewhere else, depending on your operating system.

Finally, we need to amend the network configuration file to account for the new traffic rule and route the vRack traffic through the network gateway address of 46.105.135.110.

/etc/network/interfaces

auto eth1
iface eth1 inet static
address 46.105.135.97
netmask 255.255.255.240
broadcast 46.105.135.111
post-up ip route add 46.105.135.96/28 dev eth1 table vrack
post-up ip route add default via 46.105.135.110 dev eth1 table vrack
post-up ip rule add from 46.105.135.96/28 table vrack
post-up ip rule add to 46.105.135.96/28 table vrack

Fedora

sudo dnf install iproute

CentOS 6/7

Create the file for the secondary network interface

First we can copy and use the configuration being used for the primary network interface and adjust it as per our needs:

sudo cp /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth1

Then we access to the new file:

sudo nano /etc/sysconfig/network-scripts/ifcfg-eth1

And we define the IP settings:

# Created by cloud-init on instance boot automatically, do not edit.
#
DEVICE=eth1
BOOTPROTO=static
ONBOOT=yes
USERCTL=no
IPV6INIT=no
PEERDNS=yes
TYPE=Ethernet
NETMASK=255.255.255.240
IPADDR=46.105.135.97
ARP=yes

Create a new IP routing table

Next, we need to create a new IP route for the vRack. We'll be adding a new traffic rule by amending the file, as shown below:

/etc/iproute2/rt_tables

#
# reserved values
#
255	local
254	main
253	default
0	unspec
#
# local
#
#1	inr.ruhep
1 vrack

Next, create the file needed to apply the new rules:

nano /etc/sysconfig/network-scripts/rule-eth1

And paste the following content (please remember to replace our variables with your own values):

from 46.105.135.96/28 table vrack
to 46.105.135.96/28 table vrack

Amend the network configuration file

Finally, we need to amend the network configuration file to account for the new traffic rule and route the vRack traffic through the network gateway address of 46.105.135.110.

We can achieve it by editing the following file in order to add persistent and static routes:

nano /etc/sysconfig/network-scripts/route-eth1

Paste the following content (please remember to replace our variables with your own values):

46.105.135.96/28 dev eth1 table vrack
default via 46.105.135.110 dev eth1 table vrack

Now reboot your server to apply the changes or alternatively enable simply the new network interface:

ip link set eth1 up

GNU/Linux configurations

**Debian 11**
**CentOS, AlmaLinux and Rocky Linux (8/9)**
**Ubuntu & Debian 12+**
**Fedora, AlmaLinux and Rocky Linux (10)**

Configure the Additional IP

Using a text editor of your choice, open the network configuration file located in /etc/network/interfaces.d for editing. Here the file is called 50-cloud-init.

/etc/network/interfaces.d/50-cloud-init

auto eth1
iface eth1 inet static
address 46.105.135.97
netmask 255.255.255.240
broadcast 46.105.135.111

Create a new IP routing table

Next, we need to create a new IP route for the vRack. We'll be adding a new traffic rule by amending the file, as shown below:

sudo nano /etc/iproute2/rt_tables
#
# reserved values
#
255	local
254	main
253	default
0	unspec
#
# local
#
#1	inr.ruhep
1 vrack

Amend the network configuration file

Info

For example purposes, the network configuration file we refer to is located in /etc/network/interfaces. The equivalent file on your server may be located somewhere else, depending on your operating system.

Finally, we need to amend the network configuration file to account for the new traffic rule and route the vRack traffic through the network gateway address of 46.105.135.110.

sudo nano /etc/network/interfaces.d/50-cloud-init

auto eth1
iface eth1 inet static
address 46.105.135.97
netmask 255.255.255.240
broadcast 46.105.135.111
post-up ip route add 46.105.135.96/28 dev eth1 table vrack
post-up ip route add default via 46.105.135.110 dev eth1 table vrack
post-up ip rule add from 46.105.135.96/28 table vrack
post-up ip rule add to 46.105.135.96/28 table vrack

Now reboot your server to apply the changes or alternatively simply enable the new network interface:

ip link set eth1 up

Windows Server

Step 1: Check and configure the secondary network interface

First, check the new network interface information:

check the second network interface

Then, check the properties:

properties of the second network interface properties of the second network interface

Step 2: IP Configuration

Select the Use the following IP address option:

ip configuration

Define the IP information:

ip configuration

Step 3: Rebooting the network interface

First, disable the interface.

disabling network

Then, enable the interface.

enabling network

Troubleshooting

If you are unable to establish a connection from your VM or server to the private network, please send us a ticket from your Control Panel with the following:

  • IP source and IP destination
  • Ifconfig -a or ipconfig /all from both servers or VMs (setup network configuration interface)
  • Ping in both ways
  • Arp -a
  • Routing table

Include the results above in your ticket.

Go further

Configuring the vRack on your dedicated servers

Creating multiple vLANs in a vRack

Configuring the vRack between the Public Cloud and a Dedicated Server

Join our community of users.

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