as we know, the EVPN solution includes under layer network and over layer network.

first, we must configure under layer network, the under layer network can be OSPF, BGP.

the over layer is EVPN, and EVPN depends on BGP, EVPN is implemented by extend BGP protocol.

so if you want to deploy BGP-EVPN, you must configure BGP first, then configure EVPN.

but if DCN Agile Controller, the over layer can be downloaded by Agile Controller, in this case, you just need to configure under layer.