I would suggest double checking the actual bandwidth of that interface.
My guess is the actual bandwidth is larger than 1gbps and Orion THINKS it is 1gps. If this is the case, you can manually adjust the bandwidth of the interface in Orion.
first i'd like to thank you for your reply.
for the bandwidth it's for sure 1Gbps (more exactly 7*STM1) no way to be more so that's why i couldn't understand this graph yet.
thanks in advance