Designing and Expanding the Network 2 -23
Figure 2-8. Sample Configuration Distance Calculation
To determine if your network c onfiguration is legal:
1. Use 4200 m as the maximum network diameter for a pure fiber
network as defined by the 802.3 specification.
2. Calculate the equivalent dis tances for each concentrator, and
subtract the total from 4200 (see figures for deta il s).
3. Subtract all cable lengths between the two transceivers and if the
result is greater than zero, the co nfiguration is within legal Ethernet
limits (Rule 5).
For the configuration shown in Figure 2-8 to work, ensure the fiber
equivalent distance between Transceiver A and Transceiver B is less than
4200 meters. As shown in the calculati on, there are still 1510 meters left for
expansion in this configuration . Therefore, this configuration is legal.