Connecting servers to a VLAN

Configuring VLANs (Virtual Local Area Network) on Linux servers allows you to create virtual networks to control and isolate traffic on the network.

Ubuntu 22.04.

Configuring VLANs on two Ubuntu 22.04 servers can be done using the netplan tool, which provides a convenient way to configure network interfaces in Ubuntu.

1. Configuring an untagged VLAN

Let's configure a VLAN without using identifiers (VLAN ID), but in this case it will be called an "untagged" VLAN. Untagged VLAN means that the traffic of this VLAN will be carried without VLAN tag through the physical interface.

Let's figure out the interface to configure the VLAN using theshow link command.

In this case we have enp0s8 on both servers.

2. Assigning IP addresses to VLANs

Let's find our netplan configuration; the YAML file may have different names.

Open the configuration and make changes to assign an IP address to our interface.

sudo nano /etc/netplan/*.yaml

The changes need to be made on both servers.

enp0s8:
 dhcp4: no
 addresses: [192.168.1.2/24, ]
 gateway4: 192.168.1.1 

Be careful with the syntax.

After that, apply the settings:

sudo netplan apply

Also check if the address has been assigned on the interface:

3. Ping addresses on the local network

The servers are now connected to each other using VLANs.

4. Install the VLAN package

First of all, make sure that the vlan package is installed on both servers. You can install it using the command:

sudo apt update
sudo apt install vlan

5. Also add 2 tags to our interface

All network packets will be tagged before being sent through this interface. For example, let's add two VLAN IDs 10 and 20 to the netplan configuration; all network packets will be tagged before being sent over this interface.

Open netplan and add the vlan parameters:

vlans:
 vlan10:
 id: 10
 link: enp0s8
 addresses: [192.168.1.2/24]

 vlan20:
 link: enp0s8
 id: 20
 addresses: [192.168.1.2/24]

Be careful with the syntax, as YAML is relentless.

Do the same for the second server:

 vlans:
 vlan10:
 id: 10
 link: enp0s8
 addresses: [192.168.1.1/24]

 vlan20:
 link: enp0s8
 id: 20
 addresses: [192.168.1.1/24]

Once this is done. apply the settings:

sudo netplan apply

6. Verify that everything is configured correctly

After applying the settings, verify that the VLAN is working correctly by running the ip a command to view the current network configuration on the server.

Debian 11

Configuring VLANs on two Debian servers can be done using the /etc/network/interfaces file, which provides a convenient way to configure network interfaces in Debian.

1. Configuring an untagged VLAN

Let's configure a VLAN without using VLAN IDs, but in this case it will be called an "untagged" VLAN. Untagged VLAN means that the traffic of this VLAN will be forwarded without VLAN tag through the physical interface.

First we figure out the interface to configure the VLAN using the ip link show command .

In this case we have interface enp0s8 on both servers.

2. We assign an IP address to our interface

ip addr add 192.168.1.1/24 dev enp0s8
ip addr add 192.168.1.2/24 dev enp0s8
 

We will also add this to the /etc/network/interfaces file

auto enp0s8
Iface enp0s8 inet static
 address 192.168.1.1
 netmask 255.255.255.0

Similarly for the second server:

Reboot the server:

As you can see, the address is registered
Command to check:

ip addr

After the reboot we check if the servers are pinging each other:

3. configure a tagged VLAN

All network packets will be tagged before being sent over this interface. For example, let's add VLAN ID 10 to our configuration; all network packets will be tagged before being sent over this interface.

Here enp0s8.10 is the virtual interface for VLAN ID 10, and it is configured to use the physical interface enp0s8.

Similarly for the second server:

Ip addr 192.168.1.1/24 dev enp0s8.10
Ip addr 192.168.1.2/24 dev enp0s8.10

We will also write this in the /etc/network/interfaces config so that our settings will persist after reboot.

Similarly for the second server:

auto enp0s8.10
Iface enp0s8.10 inet static
 address 192.168.1.1
 netmask 255.255.255.0
 

4. Check the vlan configuration

Enter the command:

ip addr

CentOS 7.

VLAN configuration on two CentOS servers can be done using network interface configuration files.

1. Configuring a non-tagged VLAN

Let's configure a VLAN without using identifiers (VLAN IDs), but in this case it will be called an "untagged" VLAN. An untagged VLAN means that the traffic of this VLAN will be forwarded without a VLAN tag through the physical interface.

You can find out the interface to configure the VLAN by using the command

ip addr

In this case on both servers, it is enp0s8.

2. Assign an IP address to our interface.

Open the network interfaces configuration file for editing:

sudo nano /etc/sysconfig/network-scripts/ifcfg-enp0s8

In this case, it is called in the same way as the interface.

ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
VLAN=no
IPADDR=192.168.1.1
NETMASK=255.255.255.0

3. Restart the network service

sudo systemctl restart network

4. Check if the address has been added to the interface and ping the other server

ip addr

Let's ping the servers.

The servers are available to each other.

5. Configuring a tagged VLAN

Open the network interface configuration file for editing using the physical interface ( enp0s8 in this case):

sudo nano /etc/sysconfig/network-scripts/ifcfg-enp0s8

Add the following lines to the file:

VLAN=yes
VLAN_ID=10
Также добавим идентификатор VLAN в строку DEVICE=enp0s8

DEVICE=enp0s8.10

6. Restart the network service on both servers

sudo systemctl restart network

7. Check to see if a label has been added to the interface and ping the other server

ip addr

Both servers have a connection to each other.

The tagged VLAN is configured.