The Six Subsystems of Structured Cabling
This information is based generic and typical commercial building infrastructures.
1. Entrance Facilities (EF)
Entrance facilities contain the cables, network demarcation point(s), connecting hardware, protection devices and other equipment that connect to the access provider (AP) or private network cabling. It includes connections between outside plant and inside building cabling.
The backbone cabling provides interconnection between telecommunications rooms, equipment rooms, access provider (AP) spaces and entrance facilities. There are two subsystems defined for backbone cabling:
- Cabling Subsystem 2 – Backbone cabling between the horizontal cross-connect (HC) [Distributor A (DA)] and the intermediate cross-connect (IC) [Distributor B (DB)]
- Cabling Subsystem 3 – Backbone cabling between an intermediate cross-connect (IC) [Distributor B (DB)] and the main cross-connect (MC) [Distributor C (DC)]
- 100-ohm twisted-pair cabling: Category 3, Category 5e, Category 6 or Category 6A
- Multimode optical fiber cabling: 850 nm laser-optimized 50/125 μm is recommended; 62.5/125 μm and 50/125 μm is allowed
- Single-mode optical fiber cabling
The horizontal cabling system extends from the work area’s telecommunications information outlet to the telecommunications room (TR) or telecommunications enclosure (TE). It includes horizontal cable, mechanical terminations, jumpers and patch cords located in the TR or TE and may incorporate multiuser telecommunications outlet assemblies (MUTOAs) and consolidation points (CPs). The maximum horizontal cable length shall be 90 m (295 ft.), independent of media type. If a MUTOA is deployed, the maximum horizontal balanced twisted-pair copper cable length shall be reduced.
- 4-pair 100-ohm unshielded or shielded twisted-pair cabling: Category 5e, Category 6 or Category 6A
- Multimode optical fiber cabling, 2-fiber (or higher fiber count)
- Single-mode optical fiber cabling, 2-fiber (or higher fiber count)
Work area (WA) components extend from the telecommunications outlet/connector end of the horizontal cabling system to the WA equipment. A minimum of two telecommunications outlets (permanent links) should be provided for each work area. Multiuser telecommunications outlet assemblies (MUTOAs), if used, are part of the WA.