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Configuring an Additional IP block in a vRack

Stephanie R.
Updated

Learn how to configure a block of public IP addresses for use with the vRack.

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.

Limitations:

  • IP blocks added to the vRack are limited to 5 Gbps.
  • This feature might be unavailable or limited on servers of the Eco product line.
  • Additional IP blocks purchased in the Singapore and Mumbai (YNM) data centers are not supported by vRack services.

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 our Configuring an Additional IPv6 block in a vRack guide.

This article focuses on Additional IP configuration over a vRack network. If you need guidance on Additional IP configuration with the primary IP (on the 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
  • An active vRack service in your account

OVHcloud Control Panel Access

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

 

Instructions

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, 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

NOTE: 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 two usable IPs or more for this to be possible.

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

configureIPonVRack.png

 

Configure a usable IP address

NOTE: The IP blocks must be configured on the private interface.

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 usable address is the second address in the block, as shown in the example 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. We will also need to use a subnet mask (255.255.255.240).

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 telling 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.

sudo apt-get install iproute2

Fedora

sudo dnf install iproute

 

Configure your VM

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

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 enable the new network interface:

ip link set eth1 up

Create the file for the secondary network interface

First, copy the primary network interface configuration and adjust it as needed:

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

Then, open the new file:

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

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:

sudo nano /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.

Edit the following file 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 enable the new network interface:

ip link set eth1 up

Configure the Additional IP:

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

sudo nano /etc/netplan/50-cloud-init.yaml

Define the IP settings with the following variables:

NETWORK_INTERFACE:
dhcp4: false
addresses:
- ADDITIONAL_IP/PREFIX
routes:
- to: NETWORK_IP/PREFIX
  via: GATEWAY_IP

Example:

eno2:
dhcp4: false
addresses:
- 46.105.135.97/28
routes:
- to: 46.105.135.96/28
  via: 46.105.135.110

Apply the configuration with the following command:

sudo netplan apply

First, verify that your vRack interface is connected or connecting state. In our example, the interface is called eno2.

nmcli device status

DEVICE     TYPE      STATE                                  CONNECTION
eno1       ethernet  connected                              cloud-init eno1
lo         loopback  connected (externally)                 lo
eno2       ethernet  connecting (getting IP configuration)  vRack

Next, retrieve the name of the configuration file located in /etc/NetworkManager/system-connections for editing. Here the file is called vRack.nmconnection.

[user@server ~]$ cd /etc/NetworkManager/system-connections
cloud-init-eno1.nmconnection vRack.nmconnection

Using the nmcli handler, configure your Additional IP. Replace vRack and other parameters with your own values.

  • Add the IP
sudo nmcli connection modify vRack IPv4.address 46.105.135.96/28
  • Add the Gateway
sudo nmcli connection modify vRack IPv4.gateway 46.105.135.110
  • Change the configuration from auto to manual:
sudo nmcli connection modify vRack IPv4.method manual
  • Make the configuration persistent
sudo nmcli con mod 'vRack' connection.autoconnect true

 

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 (1 vrack) by amending the file, as shown below:

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

Add the route:

sudo ip route add <network_ip>/<prefix> via <gateway> dev <interface>

Example:

sudo ip route add 46.105.135.96/28 via 46.105.135.110 dev eno2

Restart your network with the following command:

sudo systemctl restart NetworkManager

Step 1: Check and configure the secondary network interface

First, check the new network interface information:

configureIPonVRack02*.png

Then, check the properties:

configureIPonVRack03*.png

configureIPonVRack04*.png

 

Step 2: IP Configuration

Select the Use the following IP address option:

configureIPonVRack05.png

Define the IP information:

configureIPonVRack06.png

 

Step 3: Rebooting the network interface

First, disable the interface:

configureIPonVRack07*.png

Then, enable the interface:

configureIPonVRack08*.png

 

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

Please, include the results from above in your ticket.

 

Go further

For more information and tutorials, please see our other Dedicated Servers support guides or explore the guides for other OVHcloud products and services.

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