Mobile operator made connection between MGW (third vendor) and BSC (third vendor) through
Huawei SDH equipment (OSN3500V1R7). 6-SQ1-2 port was connected to BSC, 7-SQ1-1 port was connected
to MGW. I set cross-connection 1-63 VC12 between those ports.
Enginners of BSC and MGW said that only (1-12)xVC12 to normal state, other were in down.
At OSN3500 present alarms: J0_MM, HP_TIM
We set outloop at 6-SQ1-2 port, at BSC all VC12 became normal,
set inloop at 7-SQ1-1 port, at BSC all VC12 became normal again.
Then set outloop at 7-SQ1-1 port, at MGW all VC12 became normal,
set inloop at 6-SQ1-2 port, at MGW all VC12 became normal.
Connected BSC with MGW directly through patch cords and remove OSN from scheme.
Find that the same 12xVC12 were normal, other in down state. It means that our equipment
didn't cause this trouble and problems laid in third vendor equipment.
BSC, MGW engineers compared some settings at their equipment and find that (13-63)xVC12
had different even parity - at MGW there were: (1-12)xVC12 "CRC-4" checking and
for (13-63)xVC12 - "double frame" checking. And at BSC (1-63)xVC12 use "CRC-4".
After all settings were set as "CRC-4" all services became normal. Connect BSC and MGW through OSN
all services still in normal.
Firstly, check alarms with J0, J1, J2, C2 bytes in Huawei and third vendor equipment.
Set J0, J1, J2 bytes to be recived - disable and all alarms cleared. But service at (13-63)xVC12
still didn't work.
Switch our UXCS boards working/protection, services still down.
third vendor engineers supposed that problems in our cross-connection.
During interconnection with other equipment, firstly connect other vendor equipments directly and may be you can find that problem situated in non-Huawei equipment. If you can not connect them directly, use loopbacks to find the problem place.