Setting up a secondary private subnet with a tagged VLAN on a server

In addition to the main private subnet, you can attach several secondary private subnets to the server's network interface (or the MC-LAG aggregation group) connected to a private network.

For information on how to attach or detach a secondary private subnet to a server, see this section.

Once you have changed the number or composition of secondary private subnets attached to the server, you need to configure the network interface in its operating system. Here is an example of how to configure a network interface in Linux Ubuntu 24.04 with Netplan:

1. Connect to the server over SSH:

   ssh root@<server_public_IP_address>
   

   You can also access the server via the KVM console using your username and password.

2. Find out the name of the Netplan configuration file:

   ls /etc/netplan/
   

   Result:

   50-cloud-init.yaml
   

3. Open the Netplan configuration file with a text editor. In this guide, we use nano:

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

4. To configure secondary private subnets with tagged VLANs on a server, add the vlans section to the Netplan configuration that contains information about secondary private subnets attached to the server. The settings for servers without reserved network connections and servers with MC-LAG are different. For example:

   Server without network reservation

   Server with MC-LAG

   network:
       version: 2
       ethernets:
           etx1:
               dhcp4: true
               match:
                   macaddress: b4:2e:99:58:5b:cc
               set-name: etx1
           etx2:
               dhcp4: true
               match:
                   macaddress: b4:2e:99:58:5b:ce
               set-name: etx2
       vlans:
           myvlan:
               id: <VLAN_ID>
               link: <network_interface_name>
               addresses:
                   - <IP_address_of_server_in_secondary_subnet>
               routes:
                   - to: <secondary_subnet_CIDR>
                     via: <default_gateway_of_secondary_subnet>
   

   Where:

   • myvlan: ID the virtual network (VLAN) will be assigned in the OS.

     In the vlans section, create a separate section with a unique ID for each additional private subnet attached to the server.

   • <VLAN_ID>: Unique VLAN ID assigned to the private subnet. You can look up the VLAN ID in the VLAN field on the private subnet info page in the management console.

   • <network_interface_name>: Name assigned in the Netplan configuration (the ethernets section) to the network interface connected to a private network, e.g., etx1.

     To find out which of the server's network interfaces is connected to a private network, use its MAC address: the MAC address is indicated in the management console on the server information page under Network interfaces.

   • <server_IP_address_in_secondary_subnet>: IPv4 address the server will use in the secondary subnet, with the CIDR prefix, e.g., 192.168.1.10/24.

     This address must be available and belong to the secondary private subnet range.

     Note

     You can associate only a private subnet with disabled DHCP as an additional subnet for a server.

   • <additional_subnet_CIDR>: address range available in the additional private subnet in CIDR notation, e.g., 192.168.1.0/24.

   • <default_gateway_of_additional_subnet>: IPv4 address of the default gateway in the additional private subnet you are configuring, e.g., 192.168.1.1.

   network:
       version: 2
       ethernets:
           etx1:
               dhcp4: false
               match:
                   macaddress: 58:a2:e1:ad:38:2a
               set-name: etx1
           etx2:
               dhcp4: false
               match:
                   macaddress: 58:a2:e1:ad:38:2b
               set-name: etx2
           etx3:
               dhcp4: false
               match:
                   macaddress: b8:ce:f6:40:12:d6
               set-name: etx3
           etx4:
               dhcp4: false
               match:
                   macaddress: b8:ce:f6:40:12:d7
               set-name: etx4
       bonds:
           bond1:
               dhcp4: true
               interfaces:
               - etx3
               - etx1
               macaddress: b8:ce:f6:40:12:d6
               parameters:
                   lacp-rate: fast
                   mode: 802.3ad
                   transmit-hash-policy: layer3+4
           bond2:
               dhcp4: true
               interfaces:
               - etx4
               - etx2
               macaddress: b8:ce:f6:40:12:d7
               parameters:
                   lacp-rate: fast
                   mode: 802.3ad
                   transmit-hash-policy: layer3+4
       vlans:
           myvlan:
               id: <VLAN_ID>
               link: <network_interface_name>
               addresses:
                   - <IP_address_of_server_in_secondary_subnet>
               routes:
                   - to: <secondary_subnet_CIDR>
                     via: <default_gateway_of_secondary_subnet>
   

   Where:

   • myvlan: ID the virtual network (VLAN) will be assigned in the OS.

     In the vlans section, create a separate section with a unique ID for each additional private subnet attached to the server.

   • <VLAN_ID>: Unique VLAN ID assigned to the private subnet. You can look up the VLAN ID in the VLAN field on the private subnet info page in the management console.

   • <network_interface_name>: Name assigned in the Netplan configuration (the bonds section) to the aggregation group connected to a private network, e.g., bond1.

     Learn how to find out which aggregation group is connected to a private network in this section.

   • <server_IP_address_in_secondary_subnet>: IPv4 address the server will use in the secondary subnet, with the CIDR prefix, e.g., 192.168.1.10/24.

     This address must be available and belong to the secondary private subnet range.

     Note

     You can associate only a private subnet with disabled DHCP as an additional subnet for a server.

   • <additional_subnet_CIDR>: address range available in the additional private subnet in CIDR notation, e.g., 192.168.1.0/24.

   • <default_gateway_of_additional_subnet>: IPv4 address of the default gateway in the additional private subnet you are configuring, e.g., 192.168.1.1.

   If you have detached all secondary private subnets from the server, delete the vlans section from the settings file.

5. Apply updated Netplan settings:

   netplan apply
   

Useful linksUseful links

• Reserving a BareMetal network connection using MC-LAG
• Network