Information Technology Reference
In-Depth Information
Typical backbone runs
Typical
horizontal
runs
*
MC
TR's
Optional
MUTOA
Work
area
Key:
Termination
MC = Main cross-connect
Interconnect or cross-connect
Hub equipment
TR =Telecommunications room
MUTOA = Multi-user telecom.
outlet adapter
Opt = Optional
Work area telecom.
outlet connector
* These runs are technically user cords if MUTOA is used and may connect directly to
workstation. Otherwise, they are a continuation of the horizontal cable.
FIGURE 11.7
A typical structured fiber layout.
cord, and it would be tedious and costly to replace a damaged user cord all the way
back to the MUTOA.
Centralized Fiber Cabling—TSB-72 and TIA-568-C
Fiber optics can support distances far in excess of those at which copper pairs fail
to work. In recognition of this fact, it is often possible to make a fiber run all the
way from a central equipment room or MC directly to the work area. This topol-
ogy is shown in Fig. 11.8. In this arrangement, the structured approach is aban-
doned for the fiber connections, and is replaced by centralized fiber cabling.
Centralized fiber has two primary advantages. The cost of each run is presum-
ably less because the system eliminates at least two connectors for each run, along
with associated termination costs, and the cost of a patch panel in each TR. In addi-
tion, a centralized fiber hub may be used, presumably at lower cost (and better port
usage) than would be the case with the hub in each TR. The centralized hub also
simplifies administration and management.
Centralized cabling was first described in TSB-72,
Centralized Optical Fiber
Cabling Guidelines
. This telecommunications bulletin supplemented TIA/EIA-568-
A to add design parameters for the use of centralized fiber runs. The -B and -C revi-
sions of the standard incorporates this information.
