Overview

Within the Ethernet/IEEE 802.3 standards, there exist several variants based upon Fiber Optic media. We have already briefly touched upon the most common forms of the 10Mbps fiber optic implementation, specifically 10Base-FL and FOIRL. In later chapters, we will meet those that relate to higher bandwidths such as 100Base-Fx and 1000Base-X. The purpose of this chapter however is to introduce two lesser-used 10Mbps specifications, namely 10Base-FP and 10Base-FB. Collectively, the 10Mbps fiber specifications are grouped together and are known simply as 10Base-F. It is these then, that we shall discuss here.

The first thing that we realize is that each of the 10Mbps Fiber specifications are incompatible with one another. Equally, when we examine how 10Base-F fits in with our other technologies, we learn that differences exist at the PLS and AUI ^[1] interface. Specifically, 10Base-F MAUs do not support the MAU isolate function or Monitor mode. Parallels can however be drawn with many aspects of the more general 10Base-X specifications. For example, as with other media types, 10Base-F MAUs do not require that an AUI is physically present. This then allows the MAU functionality to be built into devices such as Network Interface Cards (NICs). Also, since we are still dealing with a Baseband system, our devices will still contend for the network medium. In general then, although the medium itself is different, we are still dealing with a CSMA/CD system, and therefore all that we have discussed so far still applies.