3Com 5104M-FL1 installation and operation guide 10BASE-FB Fiber Backbone, 10BASE-FL to-the-Desk

❑Incoming signal from Transceiver A to the 10BASE-T Module = 420 m.

❑Outgoing signal from the 10BASE-T Module to Transceiver B = 165 m (420 m + 165 m = 585 m).

4.Subtract all cable lengths between the two transceivers (calculate copper length the same way you do for fiber). In this example, the total cable distance equals 1725 meters.

If the result from step 4 is greater than zero, the configuration is within legal Ethernet limits (Rule 5).

The calculation in this example shows that 770 meters remain for expansion in this configuration. Therefore, this configuration is legal.

10BASE-FB Fiber Backbone, 10BASE-FL to-the-Desk

Use the information in this section when designing your network using 10BASE-FB fiber as the network backbone and 10BASE-FL Modules for to-the-desk connectivity. This section assumes that the backbone is comprised of 3Com fiber products, such as the ONline Ethernet Fiber Module or ONline Ethernet 10BASE-FB Module. 3Com Ethernet Fiber modules and transceivers conform to the IEEE 10BASE-F standard.

The rules that apply to building this type of network have been covered in the previous sections. The following two additional rules apply when using ONline Ethernet Fiber Modules:

1.The equivalent fiber distance for the Fiber Module and the Port-Switching Fiber Module is:

–140 meters for signals that externally enter the module

–50 meters for signals that internally enter the module through the ONline Concentrator backplane

Designing and Expanding the Network 2 - 23