[ovs-discuss] management of tap devices

westlake westlake2012 at videotron.ca
Sat Oct 11 16:10:25 UTC 2014

I noticed when using ovs-vsctl to create tuntap devices, ovs-vsctl is 
also able to destroy the same tuntap device outside ovs.

ovs-vsctl add-port <bridge name> <tap dev> -- set Interface <tap dev> 

ifconfig -a , lists the tuntap device

This device can be taken out of the ifconfig -a list using "ovs-vsctl 
del-port ..."

However creating the tuntap device with "ip tuntap", later adding it 
with "ovs-vsctl add-port" then trying to destroy it with "ovs-vsctl 
del-port .." does not destroy the device but only deletes it from its 

The question I have is if there's a "management"/auto-creation tag I can 
set on tap devices so that the ovs daemon will auto-create them on startup.

If I can add to this, I'm actually working towards a larger problem...

The "index" networking ID number for "ip tuntap" generated tap devices 
on consecutive reboots will not match the ones stored in the ovs database.

For now I'm avoiding, debian's ifupdown interfaces file, as the problem 
is even worse.. Here I'm using edition 2.3, and the command

"ovs-vsctl add-port <bridge name> <tap dev> -- set Interface <tap dev> 
type=tap "

^ Only creates the device properly halfway. The tap device shows up 
properly with ifconfig -a, but a kvm instance complains about 
/dev/net/tun for the same tap device.

Anyone here knows these problems have been addressed with edition 2.4?

I can find workarounds with scripting around with with rc.local to get 
things working, but I'm looking for a better solution.


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