Hello Amit
Indeed MP-BGP EVPN resolves the issue of the flood and learn mechanism that multicast uses, enabling a more efficient communication using VXLAN. However, MP-BGP EVPN functions only for unicast traffic. Many services and devices will still be using BUM traffic (Broadcast, Unknown Unicast, Multicast), and this kind of traffic cannot be dealt with just using MP-BGP EVPN. There must be an underlying multicast capability to take care of such traffic.
This means that MP-BGP EVPN and the multicast underlay work in conjunction to be able to deal with all types of traffic. The use of MP-BGP EVPN is hugely efficient compared to multicast, so just the fact that the unicast traffic will use that resolves much of the efficiency issues. Let me also quote what Rene says in the lesson:
Despite MP-BGP EVPN’s advantages, we still need something for Broadcast, Unknown Unicast, and Multicast (BUM) traffic. You’ll need to configure static ingress replication or multicast for BUM traffic. In this lesson, I’ll explain how to configure MP-BGP EVPN, and we’ll use multicast for BUM traffic.
I hope this has been helpful!
Laz