"General This document presents an architecture model for interconnecting automation system elements over untrusted backhaul networks. The focus is on wireless physical la yer but is not limited to wireless. Figure 1 provides an example of the variety of (potentially simultaneous) uses for backhaul networks. In this example@ the ""Backhaul Network"" cloud could represent a shor t-distance network such as the user-owned network within a building or site@ or it could represent a potentially heterogeneous long-distance network (for example@ satellite or cellular communication networks) that are provided as a service effectively by multiple third parties. These backhaul links may be provided by one or more commercial providers such as satellite communications providers@ cellular@ LTE (see Clause 3)@ WiMax data services@ etc. Alternatively@ the backhaul may also be provided by the user??for example@ Wi-Fi services@ point-to-point microwave links@ etc"