3Com 510M-FBP, 5102M-FBP, 5104M-FB1 Choosing a Network Backbone Cabling Structure

3.Use Table 2-7 to determine the worst case loss for the 50/125 fiber cable (2000 meters x 5 dB = 10.0 dB). Add the dB losses to determine total path loss. The total path loss is 11.5 dB.

The 11.5 dB optical loss exceeds the optical power budget of 5.5 dB. Therefore the link will not work and the 10BASE-FB Module Port Status LED will signal a Low Light condition.

Thus, you must use High Power mode. When you use High power (see Table 2-4), the optical power budget of 13.5 dB is sufficient to handle the 11.5 dB path loss.

Choosing a Network Backbone Cabling Structure

Because of fiber's long-distance capabilities and immunity to noise, 3Com strongly recommends using fiber as the backbone. You can choose between two fundamental configuration topologies when connecting your network backbone using 10BASE-FB Modules in an ONline System Concentrator:

❑Star Configuration

❑Serial Configuration

2 - 14 ONline Ethernet 10BASE-FB Module Installation and Operation Guide