“As-a-service offerings have been around for more than 10 years with roots that are decades older than that, and now this ever-expanding category of service offerings includes enterprise network-as-a-service.

NaaS enables enterprises to outsource network functionality at network Layers 4-7—such as software-defined WAN (SD-WAN) and application delivery controller (ADC)—as well as Layers 1-3, which includes switches and routers.” – read more at NetworkWorld