|  | 7.1 |
| 10-Mbps and 100-Mbps Ethernet
|  | 7.1.8 |
| 100BASE-FX
At the time copper-based Fast Ethernet was introduced, a fiber version was also desired. A fiber vervsion could be used for backbone applications, connections between floors and buildings where copper is less desirable, and also in high noise environments. 100BASE-FX was introduced to satisfy this desire. However, 100BASE-FX was never adopted successfully. This was due to the timely introduction of Gigabit Ethernet copper and fiber standards. Gigabit Ethernet standards are now the dominant technology for backbone installations, high-speed cross-connects, and general infrastructure needs. The timing, frame format, and transmission are all common to both versions of 100 Mbps Fast Ethernet. 100BASE-FX also uses 4B/5B encoding. In Figure notice the highlighted waveform in the example. The top waveform has no transition, which indicates that a binary 0 is present. In the second waveform, a transition is in the center of the timing window. A binary 1 is represented by a transition. In the third waveform, there is an alternating binary sequence. In this example it is more obvious that no transition indicates a binary 0 and the presence of a transition is a binary 1. Figure summarizes a 100BASE-FX link and pinouts. Fiber pair with either ST or SC connectors is most commonly used. 200 Mbps transmission is possible because of the separate Transmit and Receive paths in 100BASE-FX optical fiber.
Web Links
100BASE-FX Components http://www.ethermanage.com/ethernet/ 100quickref/ch11qr_3.html