My company is going to upgrade some circuits from at&t basical internet circuits to MPLS circuits accross the global (due to some countries that at&t does not have MPLS present). Currently, we use GRE/IPSec tunnels (Spoke/hup) to connect to each other along with EIGRP. I was wondering if the MPLS needs BGP (as EBGP)? What will be the best practice for GRE/IPSec over MPLS? And what will be the options to interconnect MPLS network with existing at&t MIS circuit?