[ovs-discuss] Flushing queues at the OVS

Jorge Baranda jorge.baranda at cttc.es
Wed Jan 18 09:09:33 UTC 2017

Dear all,

I am working in a ring topology with 4 elements, each one running an 
instance of ovs and controlled by an SDN controller in a reactive way.
As I am having redundancy, I am trying to measure restoration 
capabilities between possible paths after a link down event and link up 
When doing iperf tests, the problem comes after the link up event (my 
sequence of actions is: flow stablishment on path1, link down, flow 
stablishment on path2, link up, turn back to path1).
The transmission stops for a long time and I imagine it could be a 
matter of buffering, which is more critical when testing TCP traffic. I 
imagine that packets get trapped in the switch off interface,
so when, the interface is up again they are transmitted, but it fact, 
they are not necessary because they should have sent previously on the 
other interface, confusing the TCP receiver and slowing down the process.
Here comes my question, is it possible to, once the interface goes down, 
flush the packets in the ovs queues? Maybe this is happening also at the 
NIC level? So, I should check both points of buffering, isn't it? Could 
you indicate me how can I also erase the queues at the NIC level?

Thank you very much for your time and attention,

With kind regards,

Jordi Baranda

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