Because of the variety of technology alternatives available from service providers, the WAN is an interesting part of the enterprise network. Depending on the services offered by the provider, the enterprise will have different levels of control over the WAN. In many cases, the enterprise will require the use of overlay logical networks to fulfill its WAN connectivity requirements. These logical overlays become more sophisticated when they must support multiple virtual networks (VNs). This chapter analyzes the different WAN scenarios the enterprise faces and discusses the technology alternatives and best practices for maintaining multiple VNs over the different WAN offerings.