[ovs-discuss] [OVN] Can flow table work when OVN controller lost connection to OVN Database

[James Guo]

Thanks. I've got it



> 在 2020年10月13日，20:40，Numan Siddique <numans at ovn.org> 写道：
> 
> On Tue, Oct 13, 2020 at 5:21 PM James Guo <guoyongxhzhf at 163.com> wrote:
>> 
>> I am not sure whether flowtable of vm continue to work when OVN controller lost connection to OVN Database
>> If flowtable continue to work, can flowtable work after vm restart?
>> 
> 
> What do you mean by flowtable continue to work ? If you mean that the
> VM's datapath is not disrupted and it can continue to send and receive
> traffic, then yes, it will work.
> 
> I did some testing and I can see that the traffic for the VM will
> continue to work as long as ovn-controller has claimed the logical
> port of the VM.
> 
> When the VM restarts and if the corresponding ovs interface is deleted
> and readded again, then I am certain that the traffic for that VM will
> be broken
> after that. That is because, when the interface is deleted,
> ovn-controller will release the interface and delete all the flows for
> that VM interface and when
> it see the interface back, it will not reprogram the flows because it
> doesn't have connectivity to Southbound database.
> 
> Thanks
> Numan
> 
>> according to http://www.openvswitch.org//support/dist-docs-2.5/ovn-architecture.7.html section Life Cycle of a VIF, it looks that flowtable will not work after vm power off
>> 
>> Thanks for your reply
>> 
>> section Life Cycle of a VIF:
>> 11.On every hypervisor, ovn-controller notices the empty  Chassis column  in the Binding table’s row for the logical port.  This means that ovn-controller no longer knows the  physical  location of  the logical port, so each instance updates its OpenFlow table to reflect that.
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