IPBH Underlay

OSPF has been chosen as an EVPN underlay protocol as opposed to Full Mesh BGP unnumbered to minimize the complexity of the network at a cost of scalability.

The Following diagram represents a single OSPF backbone area 0 spanned across two datacenters (logical circle) with each of the core switches advertising loopback addresses into the routing domain.

Flow control is achieved by influencing the cost metric of secondary link, thus ensuring that primary link is preferred for the cross sites flow

BFD is used to minimize the downtime