3Com 5112M-TPLS installation and operation guide Sample Configuration Distance Calculation

Using the sample configuration below, identify the two transceivers that are likely to be the greatest fiber equivalent distance apart. In this case, they are 10BASE-T Transceivers A and B.

Figure 2-1. Sample Configuration Distance Calculation

To determine if your network configuration is legal:

1.Use 4.2 km (4200 m) since this is the maximum network diameter for a pure fiber network (see Rule 3).

2.Calculate the equivalent distances for each concentrator, and subtract the totals from 4200 (refer to Figure 2-1 for details).

3.Subtract all cable lengths between the two transceivers. If the result is greater than zero, the configuration is within legal Ethernet limits (see Rule 5).

For the configuration shown in Figure 2-1 to work, ensure the fiber equivalent distance between transceiver A and transceiver B is less than 4200 meters. As the calculation illustrates, 1560 meters remain for expansion in this configuration.

Designing and Expanding the Network 2 - 9