Existing managed local area network (LAN) and wide area network (WAN) services, multiprotocol label switching (MPLS) and related technologies form the backbone of the enterprise customer installed base of telcos and other communication services providers and represent the majority of revenues they generate. This trend, however, has beenrapidly changing in the last three years. The software-defined network (SDN), which is closely related to network function virtualization (NFV) and software-defined WAN (SD-WAN) technologies and services, are evolving and rapidly penetrating the enterprise market.