BACnet systems can be structured in a variety of ways. Most of today's existing systems, or those currently under construction, consist of one or more building subsystems that have been tied together. Often a subsystem consists of another standard network type. These subsystems are then connected to a common backbone network (BACnet) by means of gateways. One or more workstations may likewise be connected to the backbone, either through the use of appropriate BACnet drivers (software) or by means of gateways. In the future there will be more "native" BACnet devices, devices that use BACnet as their own intrinsic communication language. Such devices will no longer need any sort of gateway. In any case, the extent of the network and the various physical media involved will dictate how it is to be structured in terms of repeaters and routers.