opper to install: The electronics (multiplexers and lasers) to convert electrical signals to optical signals, and vice versa, are costly. Specialized technicians, paid at higher levels, are required to work with and test fiber cabling. The multiplexers and interfaces between fiber-optic cabling and copper cabling in the customer's facility require local power. This adds a point of vulnerability in the event of a power outage. Fiber-optic cable is made of ultra-pure strands of glass. The narrower the core that carries the signals, the faster and farther a light signal can travel without errors or the need for repeaters. The cladding surrounding the core keeps the light contained to prevent the light signal from dispersing, that is, spreading over time, with www.TechnicalPDF.com wavelengths reaching their destination at different times. Finally, there is a coating that protects the fiber from environmental hazards such as rain, dust, scratches, and snow. An important benefit of fiber-optic cabling is that eavesdropping is more difficult because the strands have to be physically broken and listening devices spliced into the break. A splice is a connection between cables. Splices in fiber-optic cables are easily detected. Copper Cabling in Enterprises Improvements in copper cable have made it possible for unshielded, twisted-pair cabling to transmit data rates at speeds of 100Gbps in Local Area Networks (LANs). Previously, these speeds were only attainable over fiber- optic cabling. This is important because the interfaces in most computer devices are compatible with unshielded, twisted-pair (UTP) cabling, not fiber-optic cabling. Connecting this gear to fiber requires the cost and labor to install devices that change light signals to electrical signals, and vice versa. Figure 1-4 depicts copper cabling in enterprises: four pairs of wires enclosed in a sheath. Each pair consists of two strands of wire twisted together - a total of eight strands of cable, arranged by color: purple with white, orange with white, green 