[ovs-discuss] OVS 2.9.0: priority=0 actions=CONTROLLER flow counts but doesn't output packets to the controller

[Josh Bailey]

I apologize, I dropped the ball. I'll go take another look at this. I had a
go at reproducing it (with just a single table) and failed - the packet in
is sent.

It's only not sent, when FAUCET has put other flows in other tables and the
problem priority 0 rule is in table 2. I have some work to do clearly to
try and narrow that down.

I also tried setting miss length to various values and that made no
difference.



On Sat, Apr 7, 2018 at 4:42 AM Ben Pfaff <blp at ovn.org> wrote:

> On Tue, Mar 06, 2018 at 11:20:40AM -0800, Ben Pfaff wrote:
> > On Tue, Mar 06, 2018 at 06:54:30AM +0000, Josh Bailey via discuss wrote:
> > > Hoping I'm missing something obvious!
> > >
> > > I have a flow like this:
> > >
> > > $ grep CONTROLLER sab-dump-flows.log
> > >  cookie=0x5adc15c0, duration=63.446s, table=3, n_packets=60,
> n_bytes=3436,
> > > priority=0 actions=CONTROLLER:96
> > >
> > > I can cause packets to match it, but no packets are output ot the
> > > controller.
> > >
> > > faucet at faucet
> :/var/tmp/faucet-tests-1KL3eg/FaucetUntaggedTestZeroPriorityFlowsTest-test_untagged$
> > > tshark -l -n -Q -d tcp.port==40649,openflow -O openflow_v4 -Y
> > > "openflow_v4.packet_in.total_len>0" -r fa*cap|wc -l
> > > 0
> > >
> > > If I specify any priority other than 0, it works (packets are output to
> > > controller via packet in messages).
> > >
> > > Is there something special about priority=0 flows and the CONTROLLER
> action?
> >
> > Yes, in fact OpenFlow specifies special cases for priority=0 flows that
> > match no fields.  It calls these "table-miss" flows, see e.g. section
> > 5.4 in OpenFlow 1.5.1.  Open vSwitch has some explicit special-case code
> > for dealing with them.
> >
> > I can't think of a particular reason why this special case would make a
> > difference for you.  Maybe there is a bug.  Do you have a way for us to
> > reproduce it?
> >
> > Did you try "ofproto/trace"?  Maybe it will show a reason why the packet
> > is not sent to the controller.
> >
> > (I'm at a conference this week, so my schedule is weird.)
>
> I wonder whether you figured out anything here and whether you have any
> more of a bug report for us.  Happy to help, if so.
>
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