[ovs-discuss] Unable to add port to OVS Bridge.

Sudipto Biswas sbiswas7 at linux.vnet.ibm.com
Thu May 7 10:13:45 UTC 2015

On Wednesday 06 May 2015 09:32 PM, Ben Pfaff wrote:
> On Wed, May 06, 2015 at 03:19:48PM +0530, Sudipto Biswas wrote:
>> We are using Openstack to deploy close to 1000 VMs.
>> Around 5 of the deploys fail with the error:
>> /
>> //Unable to add port tap668d1203-84 to OVS bridge br-int: Operation not
>> permitted/
>> The ovs-vswitchd.log file shows:
>> /
>> //bridge|WARN|could not open network device tap668d1203-84 (No such device)/
>> Same is seen during few restart operations on the VMs
>> There are no additional logs in the ovs logs that would suggest anything
>> related to this device.
>> The OVS version being used here is OVS 2.0.0
>> Any help on how to debug this issue and what might be causing this?
> Usually that would mean that the tap had not been created at the point
> the request to add the port was issued.
Thx Ben. In ovs 2.0.0 - I could add any device (without creating it 
using ip link add) to the bridge without any issues.
I saw that this behavior has changed in 2.3.1 where the device should 
have to be created prior to the request.

In the present deployment, OVS 2.0.0 is being used. Even though, 
openstack is expected to create the device, would you
suggest that something on the kernel wasn't able to create this device 
successfully before the add-port was fired (and that is a must for the 
port to get added)?

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