• The Basics of Fiber Optic Cables
• Fiber for Physicists and Engineers
• Installing Optical Fiber
• Fiber Cable: Attributes, Geometry, and Testing
• Optical Fiber to the Desktop
• Fiber Optics in Harsh Environments

Compared to Category 5 copper, optical fiber offers you better network performance and is easier to install and test for a comparable cost. Fiber, with its virtually unlimited bandwidth, unsurpassed reliability, and ability to support all current and future protocols, is the natural choice for communication planners. Three common misconceptions have kept people from taking advantage of the medium:

• fiber-optic technology is too expensive
• fiber is difficult to install
• and copper cabling solutions will not meet their current and future requirements

There are two primary factors which have changed the cost equation:

• Fiber-based solutions cost less.
  Advances in fiber technology, higher fiber production, more affordable system electronics, and a growing base of technicians trained to install and test fiber have lowered the costs associated with fiber. There is no longer a significant premium associated with installing fiber systems. In addition, optical fiber's superior reliability reduces operating costs over the life of a network by reducing the occurrence of outages.
• Copper based solutions cost more.
  Stringent Telecommunications Industry Association (TIA) requirements established in ANSI/TIA/EIA-568A for Category 5 cables have increased the costs of installing and testing unshielded twisted pair (UTP).

Can Copper compete?

Choosing the transmission medium for your network involves more than just selecting the most cost effective solution for today's network. To ensure the long-term reliability and performance of your system, it also is important to choose a medium that can support your network requirements into the future.

While many network planners hope they can upgrade their existing copper systems to support new high-speed protocols, the fact is that very little of the current installed base -- mostly Category 3 cable can support high data rate transmissions. Upgrading to support 100 Mbps often requires pulling Category 5 cable and installing Category 5 outlets and patch panels, incurring expensive cable plant replacement and redesign. Copper upgrades demand more stringent installation, routing, testing, and warranty procedures. In addition, the copper industry already shows signs of moving to higher performance grades of cable and connectors.

Installing fiber, on the other hand, effectively 'future-proofs" your system. Optical fiber's high bandwidth supports all current and proposed protocols without laying new cable. A single fiber cable specification encompasses the full spectrum of fiber-based LAN options, including Ethernet (10 Base-F), Token Ring, fiber distributed data interface (FDDI), asynchronous transfer mode (ATM), fiber channel, and enterprise system connection (ESCON). All specify multi-mode fiber with the same physical mid optical parameters.

Copper's susceptibility to electromagnetic interference (EMI)/radio frequency interference (RFI), crosstalk, attenuation, jitter, and impedance mismatches especially at high data rates -- requires care during installation. When installing UTP, you must avoid electrical machinery, heat sources, high-voltage transmission systems, and other EMI/RFI sources, which may limit or compromise your network design.

Since optical fiber is immune to EMI/RFI interference and crosstalk, fiber-based LANs reduce error rates from a few per minute with copper to a few per' month -even at Data rates in excess of one gigabit per second.

Optical fiber's low attenuation and high bandwidth also give you the ability to transmit signals over longer distances, thereby increasing the flexibility of your design. The IEEE 802.3 10 Base F (Ethernet) standards allow operation at distances of up to 2 kilometers over fiber, but only 150 meters using Category 5 UTP. Similarly, the IEEE 802.5J Token Ring standard supports transmission distances of up to 2 kilometers using fiber, but only 180 meters using Category 5 UTP.

Installing and maintenance

People who have not worked with fiber before may be surprised to lean that it is easy to install. In fact, many technicians prefer to work with fiber cable because of its smaller diameter and lighter weight. Improvements in fiber-optic terminations make them as easy, if not easier, to terminate than Category 5 connectors. Fiber can withstand greater pulling tension and has greater crush resistance than Category 5 cable -- while Category 5 UTP can withstand up ro 25 pounds of pulling force, fiber cable can withstand more than 150 pounds.

Fiber cable is easier to maintain than copper cable. According to a 1992 user study that appeared in an industry publication, copper-based systems average 2.3 outages per year, caused primarily by EMI, RFI, crosstalk, impedance mismatches, and excessive transmission distances. Optical fiber's immunity to these factors increase network reliability by 60 to 80 percent.

While copper may seem like a familiar medium to install, Category 5 copper has more stringent installation requirements than other copper cables, many of which are just coming to light. Perhaps the most problematic issue is testing. Current test methods for Category 5 are not standardized and cannot guarantee future network performance. In addition, Category 5 test equipment is expensive, requires substantial training, and is just becoming available. Finally, since there are no industry-standard installer certification programs yet, it is difficult to identify contractors who are trained in Category 5 installation techniques.

Fiber testing, on the other hand, is simple, reliable, and requires only inexpensive equipment. Because fiber facilities are not affected by near-end crosstalk (NEXT), they generally can be tested by injecting calibrated light into one end of a fiber and measuring the light returned on the other end with a power meter. If the attenuation is within standard parameters, the system will operate over that fiber.

To help you make an educated decision about the transmission medium for your fiber to the desk (FTTD) application, the Fiber-Optic LAN Section (FOLS) of the TIA is a valuable resource. The FOLS is a consortium of leading fiber-optic cable, component, and electronics manufacturers. The FOLS focuses on educating end users and influencer's about the technical advantages and affordability of optical transmission in local area networks and fiber to the desk applications.