Subnetwork 

A building management system (BMS) is a computer-based system that controls and monitors the operations and infrastructure of a building. The BMS is made up of two main subnetworks: the field subnetwork and the control subnetwork. The field subnetwork consists of all the devices and sensors that are installed in the building, such as thermostats, lighting control systems, and security systems. The control subnetwork is made up of the computers and software that make up the BMS itself.

The purpose of the BMS is to optimize the performance of a building by controlling its temperature, lighting, security, and other systems. It can also be used to monitor energy use, identify maintenance needs, and track occupancy levels.