[Openstack-operators] [openstack-dev] [neutron] heads up to long time ovs users...

Akihiro Motoki amotoki at gmail.com
Sat Sep 22 03:55:14 UTC 2018

The important point of this notice is that packet drops will happen when
switching of_interface option from ovs-ofctl (which was the default value
in the old releases) to native (which is the current default ).

Once neutron drops the option, if deployers use the legacy value
"ovs-ofctl", they will hit some packet losses when upgrading neutron to

We have no actual data on large deployments so far and don't know how this
change impacts real deployments.

Your feedback would be really appreciated.

Best regards,
Akihiro Motoki (irc: amotoki)

2018年9月21日(金) 10:37 IWAMOTO Toshihiro <iwamoto at valinux.co.jp>:

> The neutron team is finally removing the ovs-ofctl option.
> https://review.openstack.org/#/c/599496/
> The ovs-ofctl of_interface option wasn't default since Newton and was
> deprecated in Pike.
> So, if you are a long time ovs-agent user and upgrading to a new
> coming release, you must switch from the ovs-ofctl implementation to
> the native implementation and are affected by the following issue.
> https://bugs.launchpad.net/neutron/+bug/1793354
> The loss of communication mentioned in this bug report would be a few
> seconds to a few minutes depending on the number of network
> interfaces.  It happens when an ovs-agent is restarted with the new
> of_interface (so only once during the upgrade) and persists until the
> network interfaces are set up.
> Please speak up if you cannot tolerate this during upgrades.
> IIUC, this bug is unfixable and I'd like to move forward as
> maintaining two of_interface implementation is a burden for the
> neutron team.
> --
> IWAMOTO Toshihiro
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