Hi Jun, On Wed, Feb 11, 2026 at 11:40 PM jun.gu <[email protected]> wrote: > > Hi Tiago, > > Thank you for your reply. > > I have rechecked the OpenFlow bundle behavior, and it seems that commit > https://github.com/ovn-org/ovn/commit/d53c599ed05ea3c708a045a9434875458effa21e > should indeed prevent packet drops during ovn-controller restart. My > previous understanding was incorrect — apologies for the confusion. > > By the way, could you share how large the OpenFlow flow table is in your > environment?
It depends on the chassi role, there is a role with an average of a few hundred thousand OF flows and another role with a few millions of OF flows. Regards, Tiago Pires > > Best regards, > Jun > > On 2/11/26 03:21, Tiago Pires wrote: > > Hi Jun, > > > > On Tue, Feb 10, 2026 at 8:54 AM jun.gu via discuss > > <[email protected]> wrote: > >> Hi, > >> > >> We are currently observing packet drops when `ovn-controller` restarts. > >> Our environment is running OVN 21.09 and OVS 2.16.2. > >> > >> We reviewed commit d53c599ed05ea3c708a045a9434875458effa21e, which > >> avoids dataplane downtime during the initial flow installation. However, > >> it appears that this change does not fully eliminate packet drops during > >> an `ovn-controller` restart, as the flow clearing operation still exists. > >> > >> We also looked at commit 358b1dd53dcd9dde28f47caa21ea19e755323705, which > >> ensures that all monitored updates are received before installing flows. > >> Based on these two commits, we are considering a potential optimization > >> in `ofctl.c`: > >> - In `run_S_NEW()`: modify the cookie ID of all existing flows to a > >> unified value (e.g., `0x1234`). > >> - In `ofctrl_put()`: remove the `clear flows` and `clear groups` > >> operations. > >> - In `recv_S_UPDATE_FLOWS()`: delete redundant flows whose cookie ID was > >> set in `run_S_NEW()`. > >> > > The flag ovn-ofctrl-wait-before-clear was launched a few OVN releases > > ago (I am not sure if it was OVN 22.03)for this purpose to delay to > > clear the flows. > > https://github.com/ovn-org/ovn/commit/4a34b878d02464266c2b7ff2779de121b130e065 > > > > For me it has worked well since then using > > /usr/share/ovn/scripts/ovn-ctl stop_controller --restart and upgrading > > the ovn-controller. > > Since you are using an old version maybe you could consider upgrading it. > > > > The flag ovn-ofctrl-wait-before-clear was removed recently since there > > is another mechanism to handle it. > > > >> The goal is to avoid clearing flows during restart while still ensuring > >> stale flows are properly cleaned up once updated flows are installed. > >> > >> Please let us know if this approach makes sense. If there are no > >> objections, we would like to prepare and submit a patch for further > >> discussion. > >> > >> Best regards, > >> Jun > > Regards, > > > > Tiago Pires > >> _______________________________________________ > >> discuss mailing list > >> [email protected] > >> https://mail.openvswitch.org/mailman/listinfo/ovs-discuss > -- _‘Esta mensagem é direcionada apenas para os endereços constantes no cabeçalho inicial. Se você não está listado nos endereços constantes no cabeçalho, pedimos-lhe que desconsidere completamente o conteúdo dessa mensagem e cuja cópia, encaminhamento e/ou execução das ações citadas estão imediatamente anuladas e proibidas’._ * **‘Apesar do Magazine Luiza tomar todas as precauções razoáveis para assegurar que nenhum vírus esteja presente nesse e-mail, a empresa não poderá aceitar a responsabilidade por quaisquer perdas ou danos causados por esse e-mail ou por seus anexos’.* _______________________________________________ discuss mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
