BACKBONE CABLING

Provides interconnections between telecommunications closets, equipment rooms and entrance facilities Topology: Hierarchical star (each HC is cabled to an MC or to an IC then MC) From the HC, no more than 1 cross-connect can be passed through to reach the MC Cabling for bus or ring topologies may be done if needed, in addition to the star topology Includes: Backbone cables Mechanical terminations in the intermediate and main cross-connects Patch cords or jumpers used for backbone-to-backbone cross-connection Mechanical terminations used to terminate backbone cabling in the horizontal cross-connect. Cabling between buildings Recognized Media: 100 ohm unshielded twisted pair (UTP) 150 ohm shielded twisted pair (STP-A) 62.5/125 µm optical fiber Single-mode optical fiber 50 ohm coax is a recognized media type, but not recommended for new installations and is expected to be removed from the next revision of the standard Distances: Application dependent:    Cable                   "A"                 "B"            "C" 62.5/125 fiber µm      2000 m (6560 ft)   500 m(1640 ft) 1500 m (4820 ft) Single-mode fiber      3000 m (9840 ft)   500 m(1640 ft) 2500 m (8200 ft) UTP (voice)             800 m (2624 ft)   500 m(1640 ft)  300 m (984 ft) UTP (data), STP-A Data applications, limited to 90 m (295 ft) total For UTP voice applications and fiber, the backbone distances of segment "C" may be increased if "B" is less than maximum but the total of the two must not exceed "A". Patch cords and cross-connect jumpers at the main cross-connect not to exceed 20 m (66 ft) Patch cords and cross-connect jumpers in the intermediate cross-connect should be 20 m (66 ft) or less Equipment cables should be 30m (98 ft) or less Grounding and bonding must conform to ANSI/TIA/EIA-607 as well as applicable authorities or codes