EXFO FTB-800 Series for FTB-1 - Manual (Page 290)

Test Results
280 FTB-700G/800 Series
Alarms/Errors

RDI-L (Remote Defect Indication - Line) - SONET
MS-RDI (Multiplex Section - Remote Defect Indication) - SDH
RX: Bits 6, 7, and 8 of the K2 byte contain the “110” pattern in five
consecutive frames.
TX: Generates a “110” pattern for the bits 6, 7 and 8 of the K2 byte.
Errors

FAS-S (Frame Alignment Signal - Section) - SONET
RS-FAS (Regeneration Section - Frame Alignment Signal) - SDH
RX: At least one A1 or A2 byte of the FAS word is in error.

B1 (BIP-8, Bit-Interleave Parity - 8 bits)
RX: Indicates a Section (SONET) / Regeneration Section (SDH) parity
error by performing a routine even-parity check over all frames of the
previous STS-n/STM-n signal (located in the first STS-1/STM-1 of an
STS-n/STM-n signal).

B2 (BIP-8, Bit-Interleave Parity - 8 bits)
RX:

SONET: Indicates a Line parity error by performing an even-parity
check over all bits of the LOH and SPE of the previous frame
(located in every STS-1 of an STS-n signal).

SDH: Indicates a Multiplex Section parity error by performing an
even-parity check over all bits (except those in the RSOH bytes) of
the previous frame of a STM-N signal.

REI-L (Remote Error Indicator - Line) - SONET
MS-REI (Multiplex Section - Remote Error Indicator) - SDH
RX: The M0, M1, or the combination of both M0 and M1 bytes indicate
that one or more BIP violations have been detected. Refer to M0 or
M1/Z2 (SONET) on page 426 for more information. For OC-192, also
refer to REI-L Computation Method on page 215.