NEC UPD98413 User Manual page 93

(2) Receive performance monitoring function
The events in Table 3-15 are detected when the quality of the reception line is monitored. If an event is detected,
the detection is reported to the host by an interrupt signal. The host can identify the type of the event that has
occurred by reading the corresponding register. The interrupt can be masked or unmasked for each event.
B1 error detection
Detects section layer BIP-8 error in receive data. BIP-8 operation is performed on all the frame bits one frame before (data
before frame descramble), and the result of the operation is verified with the value of the B1 byte of the current frame.
B2 error detection
Detects line layer BIP-96 error in receive data. BIP-96 operation is performed on all the bits except the first, second, and third
lines of SOH one frame before (data after frame descramble), and the result of the operation is verified with the value of the B2
byte of the current frame.
B3 error detection
Path layer BIP-8 of the receive data is checked. BIP-8 operation is performed on the STS-12c SPE area one frame before
(data after frame descramble), and the result of the operation is verified against the value of the B3 byte of the current frame.
Line REI detection (Line Remote Error Indication)
Line remote block error information. Line REI is detected when a frame having the M1 byte set to the value of 1 through 96 is
received. 0 and 97 through 255 values are no error. µPD98413 also has an optional mode which is ignored the bit 1(MSB) of
the M1 byte. This mode is set to the M1M bit of MDLOHR register, and 0 and 97 through 127 values are no error in this mode.
The value stored to the M1 byte is the number of interleaved blocks in which an error has been detected as a result of line layer
BIP-8 at the transmission destination (downstream).
Path REI detection (Path Remote Error Indication)
Path remote block error information. Path REI is detected when a frame having bits 1 to 4 of the G1 byte set to the value of 1
through 8 is received. 0 and 9 through 15 values are no error. The value stored to this area is the number of interleaved bit
blocks in which an error has been detected as a result of path layer BIP-8 operation at the transmission destination
(downstream).
CHAPTER 3 FUNCTIONAL OUTLINE
Table 3-15. Causes of Degradation in Line Quality
PRELIMINARY
NEC confidential and Proprietary
93