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ETHERNET TECHNOLOGY

Part 1: Frames, Collisions, and 10 Mbps LANs

by James Antonakos

Start ý Ethernet Frame Format ý The Interframe Gap ý Collision Or No Collision ý Detecting Errors ý Random Waiting Period ý 10-Mbps Ethernet ý 10BaseFý Errors In Ethernet LANS ý More To Come ý Sources and PDF

10BASEF

Originally, the fiber optic inter-repeater link (FOIRL) specification was used to standardize Ethernet communication over fiber. It allowed for a 1000-m fiber between repeaters. Eventually, the demand for fiber to the PC exceeded the FOIRL specifications, and a new set of fiber specifications was designed. This specification, called 10BaseF, contains three categories: 10BaseFL, 10BaseFB, and 10BaseFP. Table 4 shows a list of their properties.

The fiber link specification (10BaseFL) is the most widely used. Figure 10 shows a portion of a 10BaseFL network. Before fiber NICs became available, a 10BaseFL to 10BaseT (or 10Base2) transceiver was used to interface fiber with the PC.

The synchronous operation on the 10BaseFB link is used to reduce the delays normally associated with Ethernet repeaters that cause the interframe gap to shrink as it propagates through multiple repeaters. This allows the segment distance to be extended without compromising the collision detection mechanism.

The fiber passive specification (10BaseFP) allows groups of 10BaseFP computers to be passively connected via a hub, which optically shares signals transmitted from any station. This technology is well suited for low-power environments.

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