How to Assign Multiple VLAN IPs on a Single Linux NIC (CentOS/RHEL)

In some scenarios you may need to assign IP addresses from different VLANs to the same physical network interface on a Linux server (CentOS/RHEL). This requires the switch port to be configured as a trunk with the desired VLANs added.

Example setup

Assume a server with two Ethernet cards: ens33 for data traffic and ens38 for control/management. The data NIC will carry two VLANs:

VLAN ID 200 – network 172.168.10.0/24

VLAN ID 300 – network 172.168.20.0/24

Load the 8021q kernel module

# lsmod | grep -i 8021q   # no output means the module is not loaded
# modprobe --first-time 8021q
# lsmod | grep -i 8021q
8021q               33080  0

Verify module information:

# modinfo 8021q

Create VLAN interfaces

Use the ip command to add VLAN sub‑interfaces to ens33:

# ip link add link ens33 name ens33.200 type vlan id 200
# ip link add link ens33 name ens33.300 type vlan id 300

Bring the new interfaces up:

# ip link set ens33.200 up
# ip link set ens33.300 up

Assign IP addresses

# ip address add 172.168.10.51/24 dev ens33.200
# ip address add 172.168.20.51/24 dev ens33.300

At this point the interfaces have IPs, but the configuration is not persistent across reboots.

Make the configuration permanent

Edit the main interface file /etc/sysconfig/network-scripts/ifcfg-ens33 (if it does not exist, create it) with at least the following content:

TYPE=Ethernet
BOOTPROTO=none
DEVICE=ens33
ONBOOT=yes

Create separate files for each VLAN:

# vim /etc/sysconfig/network-scripts/ifcfg-ens33.200
DEVICE=ens33.200
BOOTPROTO=none
ONBOOT=yes
IPADDR=172.168.10.51
PREFIX=24
NETWORK=172.168.10.0
VLAN=yes

# vim /etc/sysconfig/network-scripts/ifcfg-ens33.300
DEVICE=ens33.300
BOOTPROTO=none
ONBOOT=yes
IPADDR=172.168.20.51
PREFIX=24
NETWORK=172.168.20.0
VLAN=yes

Restart the network service to apply the changes:

# systemctl restart network

After the restart, the VLAN interfaces retain their IP addresses and remain up.