[c-nsp] Cisco SFP

[Anderson Levi]

Hi,

I want to buy Cisco's gigabit SFPs for a network rollout and I've realised,
from the info I've gathered on the website, that there's a leap from the <
10km range (GLC-LH-SM) to the < 70km range (GLC-ZX-SM). The distance I have
in mind falls in between 10km and 70km.

What are the implications of using a GLC-ZX-SM module to light a stretch of
20 - 30km? Would I need to add an attenuator, given that 20km is well below
the 70km limit?

Any info would be helpful. Thanks.