Which WAN technology uses the overlay to connect remote offices?

Dynamic Multipoint Virtual Private Network (DMVPN) is a wide area network (WAN) technology that allows for virtual private networks (VPNs) to be created using the overlay of software-defined networking (SDN). Virtual Extensible LAN (VXLAN) is used to transport virtual local area network (VLAN) traffic over routed connections. Equal-cost multipath routing (ECMP) is used by Leaf and Spine switches to provide a next-hop packet forwarding decision.