[neutron] Status on BGP support when using OVN in Neutron
Daniel Alvarez Sanchez
dalvarez at redhat.com
Wed Dec 9 12:34:04 UTC 2020
On Wed, Dec 9, 2020 at 1:33 PM Daniel Alvarez Sanchez <dalvarez at redhat.com>
> Hi all,
> On Wed, Dec 9, 2020 at 10:56 AM Thomas Goirand <zigo at debian.org> wrote:
>> On 12/8/20 4:12 PM, Tim Sæterøy wrote:
>> > Hi,
>> > I'm trying to explore BGP support when using OVN in Neutron, but
>> > haven't been able to find much info on the topic. According to 
>> > committed in march 2020, OVN seems to lack similar functionality as is
>> > seen in ML2/OVS, but there's no further references:
>> >> Currently ML2/OVS supports making a tenant subnet routable via BGP,
>> >> and can announce host routes for both floating and fixed IP
>> >> addresses.
>> > I've tried searching for 'bgp' on Neutrons launchpad for issues tagged
>> > with 'ovn', in the 'ovn-org/ovn' repo or on docs.ovn.org, but I'm
>> > getting blanks.
>> > Does anyone happen to know where OVN stands on this, and especially in
>> > the context of Neutron? Or perhaps able to point me in the right
>> > direction where I can find out more? Thanks.
> Precisely, there is a talk scheduled for today in the OVS/OVN con about
> introducing BGP support in OVN  by Nutanix folks. This is more about
> EVPN and advertising /32 (or /128) to the router.
> So far, there is nothing specific in Neutron for the ML2/OVN driver.
> However, neutron-dynamic-routing project would work for you with ML2/OVN to
> advertise tenant networks but advertising FIPs is currently relying on
> having 'agent gateway' ports which consume one IP per L3 agent per compute
s/per L3 agent per compute node/per L3 agent per provider network
> This is something that ML2/OVN doesn't do so currently there's no way with
> neutron-dynamic-routing to advertise FIP host routes directly to the
> compute node.
> Can you describe the use cases that you'd have in mind or you just wanted
> to know the current status?
> Thanks a lot!
>  https://www.openvswitch.org/support/ovscon2020/
>> > : https://docs.openstack.org/neutron/victoria/ovn/gaps.html
>> > --
>> > Tim
>> As much as I know, there's no upstream (ie: OpenStack without downstream
>> modification) for BGP-to-the-host support, appart from the
>> non-mainstream callico driver, which I haven't tested.
>> However, I have been able to do a kind of "bgp-to-the-rack" where the L2
>> networking is limited to segments on a single rack. This can be done
>> adding this patch to Neutron:
>> As you can see, I did a few iteration of this patch, but now, I've been
>> told to add more db tests, which I don't have the skills for. I asked
>> for more help from the Neutron team, but so far, everyone seems busy.
>> However, I did test this, and it works kind of well. :)
>> If you wish to help to get this patch going in, please do! :)
>> Note that this doesn't use OVN. I have no idea if it would work with OVN
>> or not (I never did such a setup, only used plain OVS).
>> Now, this doesn't replace a full BGP-to-the-host setup, but hopefully,
>> the Neutron team will be able to have this done "soon" (whatever that
>> means), as interest for it is growing.
>> Thomas Goirand (zigo)
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