How does “Attenuation” affect the maximum reach of a network?

Attenuation is the loss of light signal as it travels through the fiber, measured in dB/km.

International Benchmarks: High-quality G.652.D fiber should have an attenuation of ≤ 0.35 dB at 1310nm and ≤ 0.22 dB at 1550nm. Minimizing attenuation is critical for reducing the number of expensive optical repeaters in long-distance links.