Chapter 10. Fast Ethernet Fiber Optic Media System (100BASE-FX)

The 100BASE-FX fiber optic media system provides all of the advantages of a 10BASE-FL fiber optic link segment, while operating ten times faster. Distances of 2 km (6561.6 feet) over multimode fiber optic cables are possible when operating 100BASE-FX segments in full-duplex mode. Considerably longer distances are possible when using single mode fiber segments. This is why the 100BASE-FX media system is a popular choice for Ethernet backbone networks.

In this chapter we describe the signaling and media components used in the 100BASE-FX system. We also show how a station is connected to a 100BASE-FX segment. Finally, we describe the basic configuration guidelines for a single 100BASE-FX segment.

100BASE-FX Signaling Components

The following signaling components may be used in the 100BASE-FX system to send and receive signals over the media system:

  • Ethernet interface with a built-in 100BASE-FX fiber optic transceiver.

  • Media-Independent Interface (MII).

  • External 100BASE-FX transceiver, also called a Physical Layer Device (PHY).

100BASE-FX Ethernet Interface

A 100BASE-FX interface may be equipped with a built-in 100BASE-FX transceiver, which is used to make a direct connection to the fiber optic segment. If the interface is equipped with a 40-pin MII connector, then external transceivers can be used.

Figure 10.1 shows a network adapter card designed for installation in a desktop computer. The card is equipped with a duplex ...

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