IBM's use was followed by AT&T, TABLE 5.4 Diameter, Modal bandwidth, Maximum IEEE 802.3z Optical- Standard Fiber type MHz/km distance, m Medium Limitations 1000 base-SX Multimode 1000base-SX Multimode 1000base-SX Multimode 1000base-SX Multimode 1000base-LX Multimode 1000base-LX Multimode 1000base-LX Multimode 1000base-LX Single-mode The EIA/TIA 568 building wiring standard specifies the use of 160/500-MHz/km multimode fiber. +The ISO/IEC 11801 building wiring standard specifies 200/500-MHz/km 50-um multimode fiber. #The specification for the ANSI Fibre Channel is 500/500 MHz X 50-um multimode fiber. Chapter Five and 62.5-um cable was then selected for the FDDI standard; as a result, use of 62.5-um fiber at 160/500 MHz.km became widespread in North America. However, like Mark Twain, whose rumored demise was greatly exaggerated, 50-um optical fiber still has life and in fact its use is gaining momentum in North America. While 50-um fiber has a significant advantage over 62.5-um fiber with respect to modal bandwidth and transmission distance, you might also wish to consider its handling and cost. When you do SO, as we will shortly note, 50-um fiber maintains its advantage. Concerning handling, although 50-um optical fiber has a smaller core diameter than does 62.5- um fiber, both have similar mechanical strength properties. In fact, both optical fibers have the same glass cladding diameter of 125 um. Because both types of optical fiber have the same outer diameter, they also have the same general physical characteristics and are similarly priced. Thus, when possible, 50-um cable represents a better selection than does 62.5- um cable. In fact, both 50- and 62.5-um cable are interchangeable. Although there is a one-time attenuation loss that occurs when you cou- ple 62.5-um fiber into 50-um fiber, that loss is compensated for by the greater modal bandwidth of 62.5-um cable. Thus, it is also possible to gradually install 50-um cable in all premises applications as new require- ments occur beyond your existing organizat