[ovs-discuss] tunctl tap device attached to openvswitch bridge, why the type changed to system interface

Ben Pfaff blp at nicira.com
Thu Nov 20 16:41:16 UTC 2014

On Thu, Nov 20, 2014 at 03:58:18PM +0800, zhangwqh wrote:
> I met a problem. I want to firstly create a tap device. I used the
> tool tunctl to create the tap device, After that, I attached the
> interface to openvswitch bridge. When check the type, the type is
> empty string. 

That's fine and expected.

> From the man 5 ovs-vswitchd.conf.db,
>  type: string
>               The interface type, one of:
>               system An  ordinary  network  device,  e.g.  eth0  on Linux.  Sometimes referred to as ''external interfaces'' since they are generally connected to hardware
>                      external to that on which the Open vSwitch is running.  The empty string is a synonym for system.

Note the final sentence above.

>  it seems that after attaching to bridge, the type is system
>  type. Usually the physical ethernet port is system type. When I want
>  to send the packets to vxlan device from the tap device I created
>  using tunctl(I have set a flow entry from tap device to vxlan
>  device), I found that the tap device dropped all of the packets. Can
>  anybody give me some advices why this happens?

I don't know, because I don't have enough information, but the interface
type is not what you should focus on.

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