Reducing the fiber attenuation is an efficient way to improve the system capacity and transmission distance.With the arrival of 100 G

400G communication system

thenew requirements are put forward in term of the fiber attenuation.Any progressesof even 0.01dB/ km improvement are critical to the system.However

in the current optic fiber cable specification

the maximum attenuation of a single fiber after cabling has been as a metrics

which has not effectively reflected advancement in fiber attenuation.The paper introduces the necessity of specifying link design attenuation value

and applying link design attenuation valuein network design.The reasons for cabled fiber attenuation variationare reviewed.The link design attenuation valuefor optic fiber cable linkscalculated by Monte Carlo method can provide useful guidance to estimate the linked attenuation in system design with an acceptable degree of conservatism desired by network designersare also discussed.