The network details are:
10 SDH 15454 nodes, SW 7.0, STM-16, SNCP Ring.
One node connected to LAN, and BITS1 and the rest via RS-DCC and line timing.
Created a STM-16 circuit from node with BITS clock that goes thru all other nodes and terminates back on source node.
Test set connected and configured with recovered timing and SDH VC4-16C signal to source STM-16 LR card. Destination STM-16 LR has a fiber loopback(w/10dB attenuator).
On some days Test set shows tx/Rx SDH signal error free (have seen 2 days running error free). Repeating same test again, get B3 errors ( 1 to 10 per day, or 1 each 5 minutes).
Then again 1 to 2 days error free!!!
Any idea what could be causing this other than fiber (All fiber including connectors on the STM-16 cardS are clean).
Can bad or improper grounding of nodes cause B3 errors in this form?