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Quick Reference Guide to 10-Mbps Media System

2.1 10-Mbps Media Systems

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The CSMA/CD medium access protocol and the format of the Ethernet frame are identical for all Ethernet media varieties, no matter what speed they operate at. However, the individual 10-Mbps and 100-Mbps media varieties each use different components and have very different configuration guidelines.

The original Ethernet system operates at 10-Mbps, and there are four baseband media segments defined in the 10-Mbps Ethernet standard that are described here.

FIGURE 2.1 Four 10-Mbps Ethernet media varieties

The four media types are shown with their IEEE shorthand identifiers. The IEEE identifiers include three pieces of information. The first item, "10", stands for the media speed of 10-Mbps. The word "BASE" stands for "baseband," which is a type of signaling. Baseband signaling simply means that Ethernet signals are the only signals carried over the media system.

The third part of the identifier provides a rough indication of segment type or length. For thick coax the "5" indicates the 500 meter maximum length allowed for individual segments of thick coaxial cable. For thin coax the "2" is rounded up from the 185 meter maximum length for individual thin coaxial segments. The "T' and "F" stand for "twisted-pair" and "fiber optic," and simply indicate the cable type.

The thick coaxial media segment was the first one defined in the earliest Ethernet specifications. Next came the thin coaxial segment, followed by the twisted-pair and fiber optic media segments. The twisted-pair segment type is the most widely used today for making network connections to the desktop.

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Quick Reference Guide to 10-Mbps Media System - 04 SEP 95

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