Due to some bundle size restrictions, we are looking at converting some runs over to use bi-directional fiber sfp's (the Cisco version is GLC-BX-D/GLC-BX-U). However a couple of our runs are farther than the spec 6.2 miles. Is anyone aware of a vendor that makes an inline bidirectional amp for this sort of application? I did some digging but either they do not exist or my google fu is weak today.
So you really just want the 20km optics:
GLC-BX-U20
GLC-BX-D20
Most places also make 40km and 80km optics of the same sort.
- Jared
Didn't see those. Thanks. Idiot moment for me.
specifications in lenght are for kids, adults use budgets 
bx-d bx-u form cisco have a budget of 16dBmW (max), power form -3 to -9dBm and sensivity to -19dB. So if the fiber is under -10dB (this means roughly 10/0.25dB per km SM att) you might see the light at 40km, I have a stable link for 37km whith stock bx-d bx-u