The entrance facility is the location for the Telecom Service Provider equipment and demarcation points as well as the interface with campus cabling systems; larger data centers may require multiple Entrance Facilities.
The main distribution area is the location where traffic from all areas of the Data Center converges. It’s used for conducting moves, adds and changes between core routers, SAN directors and aggregation switches.
The horizontal distribution area manages the switching and cross connection functions between server racks and between storage racks located in the equipment area.
The equipment distribution area is where you will find the storage devices and application servers that compute and store the vital data at the heart of every data center.