10BASE-FL Fiber Optic Network
2-2
Network Requirements
The link segment can be tested with a fiber optic attenuation test set that is adjusted for an 850 nm
wave length. This verifies that the signal loss in a cable is within an acceptable level:
•
13.0 dB or less for a 50/125 micron fiber-optic cable segment
•
16.0 dB or less for a 62.5/125 micron fiber-optic cable segment
•
19.0 dB or less for a 100/140 micron fiber-optic cable segment
When determining the maximum fiber optic cable length, the fiber optic budget and total network
propagation delay should be calculated and taken into consideration before fiber runs are
incorporated in any network design. Fiber optic budget is the combination of the optical loss due to
the fiber optic cable, in-line splices, and fiber optic connectors. Propagation delay is the amount of
time it takes a packet to travel the distance from the sending device to the receiving device and
back to the sending device.
If the system budgets are met, the maximum allowable fiber optic length is 2 km (6562 feet).
However, IEEE 802.3 FOIRL (Fiber Optic Inter-Repeater Link) specifications allow for a
maximum of 1 kilometer (3281 feet).
