What is the purpose of assigning an IP address to Linux VLAN? Why am I "UNKNOWN" for a "TAP" network interface


New Member
Jan 2, 2021
Hello all,

The ip address in vlan eg:

allow-vmbr0 vlan1
iface vlan1 inet static
  ovs_type OVSIntPort
  ovs_bridge vmbr0
  ovs_options tag=1
  ovs_mtu 1500

this is some kind the SVI address ? i don't understand why use that, vlan working in L2 so what is the purpose of it? Someone can explain me ?

Below i attach my most actual config:


Ok, eno1 is physical interface, that is ok.
vmbr0 bridge is virtual switch.
But what is purpose for eno1.10? this is some virtual port ?

After starting the virtual machine, a proxmox create some tap interface with id of the vm, so how connect this tap interface to particular vPort( for example eno1.10)? Do I understand it correctly?

Last one, why i have UNKNOWN state for interface (the machine is working properly):
Last edited:
This is strange, you gui screenshot show a linux bridge, but your config have an ovs internal port ?

bridge/switch are l2 only indeed, the ip address on the bridge is only to add an ip management for proxmox. (or also if you want to do routing from your vm , using this ip as gateway).
(you can't add the ip address on the physical interface , if this interface is in a bridge, that's why the ip address is set on the bridge).

about eno1.10:
this is when you use linux bridge, not ovs.
with linux bridge, historicaly, bridge don't support vlan. so the vlan tag was done when going out the physical interface.

if you create a simple "vmbr0" bridge with eno1 , and you set a tag 10 in the vm nic gui, proxmox will create at vm start a "vmbr0v10" bridge, with "eno1.10" interface.

if you use linux bridge + vlanaware option, the vlan tag is done inside the bridge directly. (like a real switch).
Same with ovs switch.

The tap interfaces are created when a vm start (1tap for each vm interface, tap<vmid>i<interfaceid>).
this tap interfaces are plugged in the vmbr bridge by proxmox dynamically. (#brctl show)



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