On Tue, Sep 01, 2015 at 07:14:00PM -0700, Pravin Shelar wrote:
> On Tue, Sep 1, 2015 at 4:56 PM, Ben Pfaff <b...@nicira.com> wrote:
> > I think I've come across a bug in OVS native tunneling, or at any rate
> > an important difference between Linux kernel and OVS native tunneling.
> > In Linux kernel tunneling, a tunnel packet received by the kernel first
> > passes through the kernel IP stack.  Among other things, the IP stack
> > drops packets that are not destined to the current host.  It appears to
> > me that the native tunneling code doesn't have any similar check,
> > because I'm seeing it accept and packets flooded by the upstream switch
> > that are not destined to an IP address of the host.  This means in
> > effect that the user of native tunneling must set "options:local_ip",
> > whereas a user of Linux kernel tunneling doesn't (and probably
> > shouldn't).
> >
> Right. Its bug.
> 
> > I suspect that this behavior is unintentional; it isn't mentioned in
> > README-native-tunneling.md or (as far as I can tell) anywhere else.
> >
> > I noticed this while testing OVN.  If you configure a few hypervisors
> > and send packets from only one of them, then the switch that connects
> > them will flood all the packets to all of the rest (since it hasn't yet
> > learned where they are).  The result is that for N hypervisors, remote
> > VIFs get N-1 copies of the packets instead of just one.  I'm appending a
> > patch that works around it, though I'd prefer to fix the tunneling code
> > rather than apply this patch.
> >
> We can fix it adding the local ip-address to tnl-port-map.
> I will send a patch.

Thanks Pravin!
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