In ADSL network we have 2 routers NE40-8 connected through SDH equipment
Green LED of POS interface is off
To make test conectivity (ping) between two routers ( NE40-8 & NE40-4) we have met problem ( can't establish the STM-1 link ) ,
after many test we have found that the problem was no compatibility in optical fiber between our router and SDH equipment.
In NE40 ( LPU board )in one end use SFP optical module for 155M POS (multi-mode , 1310 nm -2Km-) and the SDH use also the same SFP but the fiber used between them is SINGLE-MODE wich is not compatible with our module ,we have the multi-mode optical fiber but it is to short ,
no compatibility in optical fiber between our router and SDH equipment.
change the optical fiber or the SFP module to be compatible