The horizontal and vertical distribution are the core of a structured cabling system. It is based on a hierarchical architecture and a star topology. For example, consider a campus comprising two buildings: building A and building B. Building A contains the Campus Distributor (main cross-connect) which connects to two Building Distributors (intermediate cross-connects) found in buildings A and B. This distribution is called the backbone of the system or vertical distribution. In building A, a floor distributor (horizontal cross-connect) serves the work areas found in the floor. This distribution is called horizontal distribution.
1. Entrance Facility
The entrance facility is the area where the services from the Outside Plant (OSP) enter the premise. It includes the service access points and the demarcation points necessary for connecting the building to the outside plant services.
2. Main/Intermediate cross-connect
The structured cabling system is organized in a hierarchical topology. The maximum number of hierarchical levels, as per ANSI/TIA-568B standard, should not exceed two levels: the main cross-connect and the intermediate cross-connect. The main/intermediate cross-connect and the horizontal cross-connect are connected through the backbone distribution.
3. Backbone distribution
The backbone distribution is the skeleton of the structured cabling system. It connects the cross-connects with each other. It can be either based on copper systems or fiber systems. Special attention should be made when choosing the backbone distribution to meet the premise application needs, bandwidth, and distance limitations.
4. Horizontal cross-connect
The horizontal cross-connect or the floor distributor serves the floors inside a building. They connect the outlets found in work areas with the backbone cabling. All horizontal cabling terminate in the horizontal cross-connect.
5. Horizontal Distribution
The horizontal distribution includes the horizontal cabling, pathways, outlets, patch cords, and equipment cords. The horizontal distribution connects the horizontal cross-connects with the work areas present in the floor. The maximum distance permitted for the permanent link, cable running from the horizontal cross-connect to the outlet, should not exceed 90m.
6. Work area
A work area is an allocated area inside a building where occupants need data services. It is defined as a 9 meters square area where telecommunication outlets terminate. At least two telecommunication outlets are required in each work area.