> On 2/4/26 5:21 PM, Lorenzo Bianconi via dev wrote:
> > Do not forward ethernet packets with unknown ether type (0x05ff) to
> > router pipeline.
> 
> Hi, Lorenzo.  Thanks for the patch!

Hi Ilya,

thx for the review.

> 
> It would be nice to have some explanation here on why we need to drop
> these early before it reaches the router pipeline.
> 
> This patch may also use some test cases.

ack, I will add it in v2

> 
> One more thought below.
> 
> > 
> > Reported-at: https://issues.redhat.com/browse/FDP-1908
> > Signed-off-by: Lorenzo Bianconi <[email protected]>
> > ---
> >  northd/northd.c         | 9 +++++++++
> >  northd/ovn-northd.8.xml | 5 +++++
> >  2 files changed, 14 insertions(+)
> > 
> > diff --git a/northd/northd.c b/northd/northd.c
> > index b4bb4ba6d..539567ba7 100644
> > --- a/northd/northd.c
> > +++ b/northd/northd.c
> > @@ -5947,6 +5947,15 @@ build_lswitch_port_sec_op(struct ovn_port *op, 
> > struct lflow_table *lflows,
> >          return;
> >      }
> >  
> > +    if (lsp_is_router(op->nbsp)) {
> > +        ds_clear(match);
> > +        ds_put_format(match, "outport == %s && eth.type == 0x%04x",
> > +                      op->json_key, OFP_DL_TYPE_NOT_ETH_TYPE);
> > +        ovn_lflow_add(lflows, op->od, S_SWITCH_OUT_APPLY_PORT_SEC, 150,
> > +                      ds_cstr(match), debug_drop_action(), op->lflow_ref,
> > +                      WITH_DESC("Packet with unknown ether type"));
> > +    }
> > +
> >      ds_clear(match);
> >      ds_clear(actions);
> >      ds_put_format(match, "inport == %s", op->json_key);
> > diff --git a/northd/ovn-northd.8.xml b/northd/ovn-northd.8.xml
> > index 279d81f35..fe1dc4dc0 100644
> > --- a/northd/ovn-northd.8.xml
> > +++ b/northd/ovn-northd.8.xml
> > @@ -2816,6 +2816,11 @@ output;
> >      </p>
> >  
> >      <ul>
> > +      <li>
> > +        For router ports, a priority 150 flow to drop ethernet packets with
> > +        unknown ether type (0x05ff).
> 
> This does align with what I originally reported, but seeing more cases
> of random traffic being resubmitted to all routers recently, I wonder
> if we should take a default-deny approach here and instead of dropping
> specific ethertypes that we know cannot be routed by the logical router,
> drop everything that is not arp, ip or ipv6 instead.  WDYT?
> 
> This could potentially be done by restricting the default forwarding
> rule in build_lswitch_destination_lookup_bmcast() to arp, ip and ipv6.

ack, I will look into it. Do you think we should have knob to enable/disable
this behaviour?

Regards,
Lorenzo

> 
> Unicast traffic generally doesn't cause any issues for OVN and we may
> let the router pipeline deal with it (drop).
> 
> An example of the other type of traffic I witnessed was ethernet
> multicast traffic with dl_type=0x8918 that some network appliances are
> using for loop detection.
> 
> Best regards, Ilya Maximets.
> 
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