
Issue Description
Q:
Check POS interface state with "display interface pos" command and there is B1, B2 and B3 under SDH error, what is their meaning?

Handling Process
A:
For the output of display interface pos, there is B1, B2 and B3 under SDH error. e.g.
<NE80E>displsy interface pos 1/0/0
Pos1/0/0 current state : UP
Line protocol current state : UP
..........
SDH error:
section layer: B1 463371
line layer: B2 29095741 REI 220764795
path layer: B3 1208277
..........
B1: bit interleaved parity order 8, BIP-8
B2: multiplex section BIP-24. Except RSOH, parity check before scramble and it is used for bit error monitoring of multiplex monitoring.
REI: Remote Error Indication
B3: channel BIP-8. B3 is to monitor error performance of VC4 transmission in STM-N, namely, error performance of 140mb/s signal in STM―N. It is similar to B1 and B2. B3 has BIP―8 check for VC4 frame.