VLAN

This article shows how to configure a network interface as an IEEE 802.1q VLAN trunk. Ifupdown-ng includess a link executor script to support VLANs configured in the /etc/network/interfaces file.

Installation

In the previous versions of Alpine Linux, support for vlan was provided by the vlan package instead of Ifupdown-ng, as busybox-ifupdown lacked necessary features. Installing the vlan package will result in the removal of ifupdown-ng package and prevent your network from being configured/working properly.

Configuration

All the configuration on this page assumes Ifupdown-ng is being used.

Note: If ifupdown-ng is not available/used, use iface eth0.8 inet static instead of iface eth0.8 and use below address format for IPv4 instead of 203.0.113.2/24  :

Contents of /etc/network/interfaces

address 203.0.113.2 netmask 255.255.255.0

Edit the /etc/network/interfaces file as follows:

Contents of /etc/network/interfaces

auto eth0.8 iface eth0.8 address 192.168.0.2/24 gateway 192.168.0.1 vlan-raw-device eth0 vlan_id 8

The command ifup will find the trailing .8 in eth0.8 and will create a VLAN interface with vid 8 over eth0.

Alternatively with vlan8 over eth0:

Contents of /etc/network/interfaces

auto vlan8 iface vlan8 address 192.168.0.2/24 gateway 192.168.0.1 vlan-raw-device eth0

A static IP address was used in the examples shown above, but DHCP can be used as well.

Example with bridges associated with VLANs over bonding with differing MTUs on the various VLANs

This serves as an example of some of the more complicated networking possible. Particularly, this would work well for a hypervisor attached to a dedicated storage VLAN. Less complicated implementations can be achieved by merely removing the non-applicable parts as follows:

Contents of /etc/network/interfaces

auto lo iface lo inet loopback auto bond0 iface bond0 inet manual bond_slaves eth0 eth1 bond_mode 802.3ad bond_miimon 100 bond_xmit_hash_policy layer2+3 post-up ip link set dev bondi0 mtu 9000 iface bond0.1 auto br1 iface br1 address 192.168.1.196/24 gateway 192.168.1.1 bridge_ports bond0.1 bridge_stp off bridge_fd 0.0 post-up ip link set dev bond0.1 mtu 1500 iface bond0.10 inet manual auto br10 iface br10 address 192.168.10.1/24 bridge_ports bond0.10 bridge_stp off bridge_fd 0.0

Example with two interfaces on the same adapter. One with VLAN and one without

Since Linux doesn't allow multiple default gateways we need to use a second routing table using iproute2:

apk add iproute2

Then we'll add two new routing tables to the config file. One for each network:

echo "1 rt1" >> /etc/iproute2/rt_tables;echo "2 rt2" >> /etc/iproute2/rt_tables;

Now we need to edit the file /etc/network/interfaces as follow

Contents of /etc/network/interfaces

auto lo iface lo inet loopback # the native interface without a VLAN (also called untagged) auto eth0 iface eth0 address 192.168.1.100/24 gateway 192.168.1.1 post-up ip route add 192.168.1.0/24 dev eth0 src 192.168.1.100 table rt1 post-up ip route add default via 192.168.1.1 dev eth0 table rt1 # actual gateway for this interface post-up ip rule add from 192.168.1.100/32 table rt1 post-up ip rule add to 192.168.1.100/32 table rt1 # second interface with the vlan tag 5 auto eth0.5 iface eth0.5 address 192.168.5.100/24 post-up ip route add 192.168.5.0/24 dev eth0.5 src 192.168.5.100 table rt2 post-up ip route add default via 192.168.5.1 dev eth0.5 table rt2 # actual gateway for this interface post-up ip rule add from 192.168.5.100/32 table rt2 post-up ip rule add to 192.168.5.100/32 table rt2

Note that if you want to add a third interface this way, you'll have to add another routing table.

See also

• Main Networking page
• VXLAN manual for Ifupdown-ng