Virtual LANs give you the ability to sub-divide a LAN. Linux can accept VLAN tagged traffic and presents each VID as a different network interface (eg: eth0.100 for VID 100)
Previously Arch Linux used vconfig to setup VLANs. This had been superseded by the ip command. Make sure you have iproute2 installed
# pacman -Ss iproute2
Adding a VLAN
To add a VLAN use a command with this needlessly long syntax:
ip link add link INTERFACE name INTERFACE.VID type vlan id VID
ip link add link eth0 name eth0.100 type vlan id 100
Run ifconfig -a to confirm that it has been created (Non deprected alternative is to run ip link).
This interface behaves like a normal interface. All traffic routed to it will go through the master interface (in this example, eth0) but with a VLAN tag. Only VLAN aware devices can accept them if configured correctly else the traffic is dropped.
Using a name like eth0.100 is just convention and not enforced. You can alternatively use eth0_100 or something descriptive like IPTV
Configuring the VLAN
To add an IPv4 address the the just created vlan link, and activate the link you can do:
ip addr add IP/NETMASK brd BROADCAST-ADDR dev INTERFACE.VID ip link set dev INTERFACE.VID up
ip addr add 192.168.100.1/24 brd 192.168.100.255 dev eth0.100 ip link set dev eth0.100 up
De-Configuring the VLAN
To cleanly shutdown the setting before you remove the link, you can do:
ip link set dev INTERFACE.VID down
ip link set dev eth0.100 down
Removing a VLAN
Removing a VLAN interface is significantly less convoluted
ip link delete INTERFACE.VID
ip link delete eth0.100
VLANs at boot
You can use netcfg profile and put POST_UP, PRE_DOWN command to do above action. (Similar thing as done here: ) I did it for my eht0, that have is both multi-home (DHCP to the modem, and local subnet 192.168.12.0), and VLAN 112 as well. Here is an extract of a sample /etc/rc.d/my-network file:
CONNECTION='ethernet' DESCRIPTION='modem cable connection' INTERFACE='eth0' IP='dhcp' POST_UP='ip addr add 192.168.12.1/24 brd 192.168.12.255 dev eth0; ip link add link eth0 name eth0.112 type vlan id 112; ip addr add 192.168.112.1/24 brd 192.168.112.255 dev eth0.112; ip link set dev eth0.112 up' PRE_DOWN='ip link set dev eth0.112 down; ip link delete eth0.112; ip addr del 192.168.12.1/24 dev eth0'
Question: Any \ like syntax available at eol to have POST_UP split on multi-line ?
Seems it should be possible to put such control directly for netcfg into /etc/rc.conf (instead of inside the POST_UP in the netcfg profile file). Extra info on how to do that still missing ... (not clear)
possible issue is to get error in one of commands put inside POST_UP/PRE_DOWN. This can prevent to manual stop/start control of the network link
To control by hand the link after boot using the netcfg profile you put in place, you can try following commands:
/etc/rc.d/net-profiles restart /etc/rc.d/net-profiles stop /etc/rc.d/net-profiles start