[stein][neutron] gratuitous arp

Ignazio Cassano ignaziocassano at gmail.com
Mon Apr 27 16:19:16 UTC 2020

Hello, I have this problem with rocky or newer with iptables_hybrid
So, can I solve using post copy live migration ???

Il Lun 27 Apr 2020, 17:57 Sean Mooney <smooney at redhat.com> ha scritto:

> On Mon, 2020-04-27 at 17:06 +0200, Ignazio Cassano wrote:
> > Hello, I have a problem on stein neutron. When a vm migrate from one node
> > to another I cannot ping it for several minutes. If in the vm I put a
> > script that ping the gateway continously, the live migration works fine
> and
> > I can ping it. Why this happens ? I read something about gratuitous arp.
> qemu does not use gratuitous arp but instead uses an older protocal called
> to do mac address learning.
> what release of openstack are you using. and are you using iptables
> firewall of openvswitch firewall.
> if you are using openvswtich there is is nothing we can do until we
> finally delegate vif pluging to os-vif.
> currently libvirt handels interface plugging for kernel ovs when using the
> openvswitch firewall driver
> https://review.opendev.org/#/c/602432/ would adress that but it and the
> neutron patch are
> https://review.opendev.org/#/c/640258 rather out dated. while libvirt is
> pluging the vif there will always be
> a race condition where the RARP packets sent by qemu and then mac learning
> packets will be lost.
> if you are using the iptables firewall and you have opnestack rock or
> later then if you enable post copy live migration
> it should reduce the downtime. in this conficution we do not have the race
> betwen neutron and libvirt so the rarp
> packets should not be lost.
> > Please, help me ?
> > Any workaround , please ?
> >
> > Best Regards
> > Ignazio
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