As today's communication networks become more complex-as more users share peripherals, as more mission-critical tasks are accomplished over networks and as the need for faster access to information increases-a good foundation for these networks becomes increasingly important. The first step toward the adaptability, flexibility and longevity
required of today's networks begins with structured cabling-the foundation of any information system. It is vital that communications cabling be able to support a variety of applications and last for the life of a network. If that cabling is part of a well-designed structured cabling system, it can allow for easy administration of moves, adds and changes and smooth migration to new network topologies. On the other hand,"worry-about-it-when-you-need-to" systems will make moves, adds and changes a hassle and make new network topologies too difficult to implement. Network problems occur more often, and are more difficult and timeconsuming to troubleshoot.When communication systems fail, employees and assets sit idle, causing a loss of revenues and profits. Even worse, the perceptions of customers and suppliers can be adversely affected.
The purpose of this white paper is to present the advantages of using a standards-based structured cabling system for a business enterprise. The paper will cover a brief historical perspective of structured cabling, a review of the current standards, media types and performance criteria, system design and installation recommendations. Particular attention
will be given to the ANSI/TIA/EIA-568-A standard and the horizontal cabling subsystem in that standard.
The Evolution of Structured Cabling
In the early 1980s, when computers were first linked together in order to exchange information, many different cabling designs were used. Some companies built their systems to run over coaxial cables. Others thought that twinaxial or other cables would work best. With these cables, certain parameters had to be followed in order to make the system
work. Certain connectors had to be used, maximum cable distances had to be established and particular topologies were necessary.
By defining every aspect of their system, manufacturers "locked" customers into a proprietary system. One manufacturer's system would not work with another, or run over any other type of cabling. If a customer decided to change systems, not only would new electronics and software need to be purchased, but new cabling would need to be installed as well. Troubleshooting proprietary systems was very difficult and time-consuming compared to today's structured systems. A problem at one workstation could bring the entire proprietary system down, leaving no indication to the network manager where the problem may have occurred. In the case of a daisy-chain topology, troubleshooting consisted of starting at one machine and physically tracing the cables to each of the other machines on the network.
Eventually, the cause of the problem, such as a broken connection,was found. Once repairs were completed, the system would be back on line. This troubleshooting process could last hours-or days-leaving users sitting idle. Moves, adds or changes were also difficult with a proprietary system. Each time a new machine was added to the network, new cable had to be installed and inserted into the ring or attached to the bus. Furthermore, the whole system might have had to come down to add the new user.