The following tables assist you in obtaining this information:
❑Table 2-3- Lists the optical power budget for the 10BASE-FB Module
❑Table 2-6- List typical losses for connector and splice insertion loss
❑Table 2-7- Lists typical losses for various fiber cables
Calculating Maximum Link Distance
To calculate the maximum link distance allowed:
1.Determine the optical power budget for the 10BASE-FB port (Table 2-3).
2.Subtract the optical power loss due to patch panels and splices (Table 2-6) from the optical power budget for the 10BASE-FB port.
3.Subtract the dB loss/km rating of the fiber cable (Table 2-7) from the remainder of step 2. If the result is greater than 0, the link distance is valid.
4.If the device connecting to the 10BASE-FB Module does not have the same optical budget as the 10BASE-FB Module, you must also calculate the maximum link distance for the connecting device.
Determining Link Budget
To ensure link integrity, you should plan for worst case losses through the end-to-end optical connection. The optical power budget represents a worst case that assumes the transmitter is transmitting at the low end of its range. When possible, 3Com recommends using Normal power.
Designing and Expanding the Network 2 - 7
