Open Stack

Hi,

On Tue, Sep 08, 2020 at 02:46:29PM +0000, Alexis Deberg wrote:
> Hi All,
> 
> I'm looking for ideas as we need to upgrade our Neutron deployment and it looks like it would impact workloads a bit much for now to do so and i'm no master of the neutron code...
> 
> We're running Neutron 14.0.2 with ml2 plugin and firewall_driver set as openvswitch. drop_flows_on_start is default False.
> 
> Reading at some old bug reports my understanding was that a restart of the neutron-openvswitch-agent should not impact existing flows and be seamless, but this is not what I'm experiencing as I see some temporary drop(s) around when ovs-fctl del-flows/add-flows is called on br-int (either east-west traffic or north-south). I tried switching to iptables_hybrid driver instead and I don't see the issue in that case.
> 
> e.g when a wget download is happening on an instance while the agent is restarting, I see the following: 2020-09-08 14:26:09 (12.2 MB/s) - Read error at byte 146971864/7416743936 (Success). Retrying
> 
> I'm a bit lot so i'm wondering if that's expected/known behavior, if a workaround is possible....

I don't think it is expected behaviour. All flows should be first installed with
new cookie id and then old ones should be removed. And that shouldn't impact
existing traffic.

> 
> Let me know if a bug report might be a better place to dig deeper or not or if you want additional information... or if I missed a closed bug.

Yes, please report bug on Neutron's launchpad. And, if that is possible, please
also try to reproduce the issue on current master branch (maybe deployed from
devstack simply).

> 
> Thanks !

-- 
Slawek Kaplonski
Principal software engineer
Red Hat