Dear Pix, good evening!
About our experiment and results:
Three times we repeated that experiment (different MFSs, different types of BSCs, etc). But all the same – we had no success. Alcatel’s magic is much more complicated 🙂 So we’re waiting answer and help from our TAC.
While it is silence we also have been trying to analyze this problem by ourselves. I’ve noticed one thing – that abnormal TBF drop due to BSS correlates perfectly with counter P103 (“Number of GCH frames badly received by the MFS (due to a bad CRC)” Whenever the EGCH layer detects that a GCH frame has not been correctly decoded in the MFS (due a bad CRC) ).
The difference between values of this counter for “normal” BSCs and for those BSCs with high TBF drop is not times or hundreds, it’s thousands (pictures in NPO are astonishing). I don’t know now either it is a hint which could help to analyze this problem or it’s only an obvious consequence 🙂 I understand what CRC is and what is its purpose, but I can’t find any details about the process of its calculations, which could help us to understand how to solve our problem, especially – about it’s calculation for packet data…
Now we’re elaborating two propositions: one – rebooting MFSs and other – deactivating CRC check for one or two BSCs…..
Maybe we’ll be lucky :))))))
I’ll share the results.