The document discusses a legacy MPLS/IP VPN WAN and the challenges enterprises now face in securely supporting an increasing number of services, sites, and devices. It proposes a hybrid WAN solution using MPLS, internet, and SD-WAN to provide scalability, cost efficiencies, high availability, and performance. Case studies show how Level 3 has implemented hybrid WAN solutions for large customers to connect thousands of retail locations and provide managed network services.