[ovs-discuss] ovn not creating geneve tunnels

Lars Kellogg-Stedman lars at redhat.com
Tue Jan 14 22:57:51 UTC 2020


Han,

It looks as if that patch may resolve the issue. I backported it to 2.12.0
and built some updated RPMS for Fedora 31; with those in place, the tunnels
come up immediately.

On Tue, Jan 14, 2020 at 1:03 AM Han Zhou <hzhou at ovn.org> wrote:

>
>
> On Mon, Jan 13, 2020 at 6:52 PM Flavio Fernandes <flavio at flaviof.com>
> wrote:
> >
> >
> >
> > > On Jan 10, 2020, at 8:55 PM, Lars Kellogg-Stedman <lars at redhat.com>
> wrote:
> > >
> > > Flavio,
> > >
> > > I wanted to expand on our irc discussion earlier today.  Here's what
> > > I'm seeing:
> > >
> > > If I run this command...
> > >
> > >  ovs-vsctl set open_vswitch .  \
> > >    external_ids:ovn-remote=tcp:192.168.122.100:6642 \
> > >    external_ids:ovn-encap-ip=$(ip addr show eth0 | awk '$1 == "inet"
> {print $2}' | cut -f1 -d/) \
> > >    external_ids:ovn-encap-type=geneve \
> > >    external_ids:system-id=$(hostname)
> > >
> > > Then OVN (reliably) does not immediately bring up the geneve tunnels:
> > >
> > >  [root at ovn1 ~]# ovs-vsctl show
> > >  b55f79a1-686a-40c9-90c5-3cca33b02517
> > >      Bridge br-int
> > >          fail_mode: secure
> > >          Port br-int
> > >              Interface br-int
> > >                  type: internal
> > >      ovs_version: "2.12.0"
> > >
> > > In this situation, the tunnels will come up if I restart
> > > ovn-controller, or if I bind some ports that require connectivity
> > > between hosts. Everything seems to *work*, but the behavior differs
> > > from what I was seeing earlier.
> > >
> > > It turns out that if I set the same configuration using multiple
> > > commands (which is what I was originally doing), like this...
> > >
> > >  ovs-vsctl set open_vswitch . external_ids:ovn-remote=tcp:
> 192.168.122.100:6642
> > >  ovs-vsctl set open_vswitch . external_ids:ovn-encap-ip=$(ip addr show
> eth0 | awk '$1 == "inet" {print $2}' | cut -f1 -d/)
> > >  ovs-vsctl set open_vswitch . external_ids:ovn-encap-type=geneve
> > >  ovs-vsctl set open_vswitch . external_ids:system-id=$(hostname)
> > >
> > > ...then the geneve tunnels come up without any additional changes:
> > >
> > >  [root at ovn1 ~]# ovs-vsctl show
> > >  7ca1a9c6-f035-493a-94a9-31474dd6cf77
> > >      Bridge br-int
> > >          fail_mode: secure
> > >          Port "ovn-ovn2-0"
> > >              Interface "ovn-ovn2-0"
> > >                  type: geneve
> > >                  options: {csum="true", key=flow,
> remote_ip="192.168.122.102"}
> > >                  error: "could not add network device ovn-ovn2-0 to
> ofproto (File exists)"
> > >          Port br-int
> > >              Interface br-int
> > >                  type: internal
> > >          Port "ovn-ovn0-0"
> > >              Interface "ovn-ovn0-0"
> > >                  type: geneve
> > >                  options: {csum="true", key=flow,
> remote_ip="192.168.122.100"}
> > >      ovs_version: "2.12.0"
> > >
> > > Although as you can see the tunnels don't always come up "cleanly". I
> > > get that "could not add network device ovn-ovn2-0 to ofproto (File
> > > exists)" fairly often, but not all the time.
> > >
> > > And it's not always the same tunnel throwing the error; after a couple
> > > more tries, I see:
> > >
> > >          Port "ovn-ovn0-0"
> > >              Interface "ovn-ovn0-0"
> > >                  type: geneve
> > >                  options: {csum="true", key=flow,
> remote_ip="192.168.122.100"}
> > >                  error: "could not add network device ovn-ovn0-0 to
> ofproto (File exists)"
> > >
> > > Something here seems racy and/or non-deterministic.  I'm running
> > > openvswitch/ovn 2.12.0 on Fedora 31 (kernel 5.4.8-200.fc31.x86_64).
> >
> >
> > Indeed sounds like a timing thing, affected by when the attributes are
> done in a single ovsdb transaction or
> > separately. I will try to reproduce it on my setup using your findings
> as guide.
> >
> > And thanks for cc'ing the ML. There are a lot of really smart people
> here who may have a good idea on
> > why this is happening.
> >
> > Best,
> >
> > -- flaviof
> >
> I am not 100% sure if it is the same problem, but could you try this patch
> and see if it helps?
> https://patchwork.ozlabs.org/patch/1222380/
>
> Thanks,
> Han
>


-- 
Lars Kellogg-Stedman <lars at redhat.com>
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