On Wed, May 13, 2026 at 11:48 AM Chanyeol Yoon <[email protected]> wrote:

> Hi,
>
> While testing OVN native BGP-EVPN (dynamic-routing-vni) in a
> Kube-OVN based environment, I noticed that Floating IPs (FIP)
> are not advertised via EVPN Type-2 routes.
>
> == Observed behavior ==
>
> When a VM is directly attached to an EVPN-enabled Logical Switch,
> its MAC/IP appears correctly in the advertised_mac SB table and
> FRR advertises it as Type-2.
>
> However, when a FIP (NAT type=dnat_and_snat with external_mac and
> logical_port set) is associated with a VM on a tenant network,
> the FIP's external_ip/external_mac does NOT appear in advertised_mac.
>
> == Root cause ==
>
> en-advertised-route-sync.c iterates over Logical Switch Ports (LSPs)
> only. NAT entries on the Logical Router are not processed, so
> external_ip/external_mac from dnat_and_snat rules are never populated
> into advertised_mac.
>
> == Expected behavior ==
>
> For NAT rules with:
>   - type = dnat_and_snat
>   - external_mac set
>   - logical_port set
>
> ovn-northd should create an advertised_mac entry so that
> ovn-controller can inject a static FDB entry into lo-$VNI,
> allowing FRR to advertise the FIP as a Type-2 route.
>
> == Environment ==
>   - OVN 26.03
>   - Kube-OVN v1.15 (custom build)
>   - FRR 8.4.4
>   - OpenStack (Neutron ML2/OVN)
>
> == Question ==
>
> Is this an intentional limitation or a gap that hasn't been
> addressed yet? I'm happy to work on a patch if the direction
> is agreed upon.
>
> Thanks,
> Chanyeol Yoon
> KT Cloud
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>
>
Hi Chanyeol,

yes you are right, this is not yet supported by OVN.
I suppose this was more of an oversight than intent.
So from my perspective it's fine to add it.

Also the proposal touches on a slightly different topic,
the loopback is used for FDBs, but FDBs are not populated
based on advertised_mac_bindings (they probably should be too).

So we would actaully require two changes, one to add FIPs into
advertised_mac_binding and the second to use those for FDBs.

Feel free to give the implementation a shot, we can discuss
details on a patch.

Regards,
Ales
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