RouteAdvertisments selected networks might be configured with EVPN and the RouteAdvertisments controller should produce the appropriate FRRConfiguration for them.

Currently a list of selected BGP routers is derived from the FRRConfiguration selector of a RouteAdvertisments and a transformation of these routers is applied in generated FRRConfigurations. However the way the routers are manipulated for EVPN configured network changes:

• EVPN underlay is assumed to happen on the default VRF, so routers on the default VRF should be updated to activate EVPN. Within the default VRF EVPN section we might need to setup routemaps to filter out the management port MACs from being advertised, as well as route targets of MACVRFs.
• Routers on the CUDN VRFs need to be updated to advertise its subnets in the unicast family as well as import them into the EVPN family where we should also setup the route targets for the IPVRF. If Routers on the CUDN VRFs haven't been selected, we should potentially assume they don't exist and consider adding them.
• The IPVRF to VNI mapping needs to be added.

For the most part we will use the raw FRRConfiguration stanza. A follow up task will update the logic to use proper FRR-K8s API once it is provided.

The upstream enhancement contains additional details and examples.