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

Therefore, for each pair of ONline Fiber Modules that a signal passes through, there is a fiber equivalent distance of 190 meters (140 m + 50 m = 190 m). In addition, a signal making a round trip through the module (that is, entering a port externally and exiting through another port on the same module) counts as 190 meters of fiber equivalent distance.

2.Do not count the ONline Ethernet Fiber Module and the ONline Ethernet Port-Switching Fiber Module as repeaters when determining the maximum number of repeaters in your network. These are repeater-less devices.

Example: Fiber Backbone, 10BASE-FL to-the-Desk

Use the following example to determine if the 10BASE-FL transceivers are within legal Ethernet limits. First identify the two transceivers that are likely to be the greatest distance apart in Figure 2-8. In this case, they are 10BASE-FL transceivers A and B

.

Concentrator A

Fiber Module

10BASE-FL

10BASE-FL Module

450 m

A

Concentrator B

1. Maximum

4200 m

Diameter

2. FL

330 m + 230 m

10BASE-FL

Modules

= 560 m

Equivalent Distance

1000 m

10BASE-FL Module

75 m

B

3. Fiber 50 m+190 m+140 m

Modules

= 380 m

Equivalent Distance

500 m

4. Cable Distance

2025 m

Concentrator C

(450 m + 1000 m +

10BASE-FL

500 m + 75 m)

C

Remaining

50 m Fiber Module

Distance

1235 m

Figure 2-8. Sample Fiber Backbone, 10BASE-FL to-the-Desk Configuration

2 - 24 ONline Ethernet 10BASE-FL Installation and Operation Guide