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By far the most common media types have been covered elsewhere in this chapter: 10BASE-5, 10BASE-2, 10BASE-T, 100BASE-T, 100BASE-TX, and 100BASE-T4. However, all of these use coaxial or twisted-pair wiring.
There are also several different standards for placing Ethernet frames on fiber optic cabling. In particular, 10BASE-F is used here at Ball State to make connections between buildings and often between a hub located in the utility area in the basement of most buildings and the upper floors of the buildings. Fiber optic cables able to carry the frames for more than the limited 500 meters of 10BASE-5 without the use of a repeater due to a lesser degree of signal degradation. However even the speed of light is finite: the propagation delay over a thousand meters of fiber optic cable is at least 3 (and may be more due to the bouncing of light within the cable) microseconds which needs to be taken into account when being sure that the total propagation delay between any two interfaces is at most 25 microseconds.
The point that must be made clear is that just because fiber is in use, one will not see a higher bit rate. In fact, some of the fibers buried at Ball State are carrying 19.2 kbps serial communications. Fiber is simply used to overcome distance limitations in many cases. It is true that over the same distances, fiber is capable of supporting higher bit rates than ordinary twisted pair wiring, but it is often used at well below its capacity. What determines the actual bit rate is the interface to the fiber or wiring, not the fiber or wiring itself (although use of a high-speed interface on low quality media is bound to fail).
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