Structured cable system topologies

TIA/EIA-568-C defines a hierarchical cable system architecture, in which a main cross-connect (MCC) is connected via a star topology across backbone cabling to intermediate cross-connects (ICC) and horizontal cross-connects (HCC). Telecommunications design traditions utilized a similar topology, and many people refer to cross-connects by their older, nonstandard names: "distribution frames" (with the various hierarchies called MDFs, IDFs and wiring closets).

Backbone cabling is also used to interconnect entrance facilities (such as telco demarcation points) to the main cross-connect. Maximum allowable backbone fibre distances vary between 300m and 3000m, depending upon the cable type and use.

Horizontal cross-connects provide a point for the consolidation of all horizontal cabling, which extends in a star topology to individual work areas such as cubicles and offices. Under TIA/EIA-568-B, maximum allowable horizontal cable distance is 90m of installed cabling, whether fibre or twisted-pair, with 100m of maximum total length including patch cords. No patch cord should be longer than 5m. Optional consolidation points are allowable in horizontal cables, often appropriate for open-plan office layouts where consolidation points or media converters may connect cables to several desks or via partitions.

At the work area, equipment is connected by patch cords to horizontal cabling terminated at jackpoints.TIA/EIA-568-B also defines characteristics and cabling requirements for entrance facilities, equipment rooms and telecommunications room

November 29, 2011

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