Backbone
Backbone cable connects two or more wiring closets in an extended star topology.
Backbone cabling also connects wiring closets to the POP and wiring closets between buildings. It does not connect workstations.
Backbone cabling is sometimes called vertical cabling to distinguish it from horizontal cabling, which does connect hubs to workstations. EIA/TIA-568 specifies five different options for the backbone cabling:
- 100 ohm UTP
- 150 ohm STP
- 62.5/125 micron optical fiber (most popular for new installations)
- Single-mode optical fiber
- 50 ohm coaxial cable (not recommended)