[ovs-discuss] Vlan transparency in OVN

Slawek Kaplonski skaplons at redhat.com
Thu Jun 4 07:53:12 UTC 2020


On Tue, Jun 02, 2020 at 05:37:37PM -0700, Ben Pfaff wrote:
> On Tue, Jun 02, 2020 at 01:25:05PM +0200, Slawek Kaplonski wrote:
> > Hi,
> > 
> > I work in OpenStack Neutron mostly. We have there extension called
> > "vlan_transparent". See [1] for details.
> > Basically it allows to send traffic with vlan tags directly to the VMs.
> > 
> > Recently I was testing if that extension will work with OVN backend used in
> > Neutron. And it seems that we have work to do to make it working.
> > From my test I found out that for each port I had rule like:
> > 
> >     cookie=0x0, duration=17.580s, table=8, n_packets=6, n_bytes=444, idle_age=2, priority=100,metadata=0x2,vlan_tci=0x1000/0x1000 actions=drop
> > 
> > which was dropping those tagged packets. After removal of this rule traffic was
> > fine.
> > So we need to have some way to tell northd that it shouldn't match on vlan_tci
> > at all in case when neutron network has got vlan_transparency set to True.
> > 
> > From the discussion with Daniel Alvarez he told me that somehow we can try to
> > leverage such columns to request transparency (for example: parent_name=none
> > and tag_request=0). With this, northd can enforce transparency per port.
> > 
> > Another option could be to create an option in the “other_config” column in the
> > logical switch to have the setting per Neutron network
> > (other_config:vlan_transparent) While this seems more natural, it may break the
> > trunk/subport current feature.
> > 
> > What do You, as ovn developers thinks about that?
> > Is that maybe possible somehow to do currently in northd? Or is one of the
> > options given above doable and acceptable for You?
> This might be a place to consider using QinQ (at least, until Neutron
> introduces QinQ transparency).

I'm not sure if I understand. For now Neutron don't supports QinQ - old RFE is
postponed currently [1].
And my original use case is related to the Neutron tenant networks which is
Geneve type. How QinQ can help with that?


[1] https://bugs.launchpad.net/neutron/+bug/1705719

Slawek Kaplonski
Senior software engineer
Red Hat

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