EXFO FTB-800 Series for FTB-1 - Manual (Page 435)

Test Functions
NetBlazer 425
OH - SONET/SDH

B2
1
: BIP-8
SONET: The BIP-8 (Bit-Interleaved Parity) byte provides line error
monitoring. The byte is calculated by performing a routine even-parity
check over all bits of the LOH and the STS-1 frame capacity of the
previous frame of a composite signal (STS-1 to STS-n). Note that the
SOH is not used to calculate the parity check.
SDH: The MS BIP-N*24 (Bit-Interleaved Parity) byte provides line error
monitoring. The byte is calculated by performing a routine even-parity
check over all bits of the MSOH and the STM-N frame of the previous
STM-N frame. Note that the RSOH is not used to calculate the parity
check.

K1
1
and K2
1
: Automatic Protection Switching (APS): The K1 and K2
bytes communicate APS between two LTE.

D4
1
through D12
1
: Data Communications Channel (DCC): The D4
through D12 bytes provide a 576 Kbit/s data communications channel
between two LTEs for administration, monitoring and other
communications.

S1/Z1 (SONET)
S1
1
: Synchronization Status: The S1 byte is used to carry the
synchronization status of the SONET device.
Z1: Growth. This byte is located in the second STS-1 through STS-n
frame of a composite signal (STS-1 #2, STS-1 #3, up to STS-1 #N of a
OC-N (N>3) signal).

S1 (SDH)
1 : Synchronization Status. Bits 5 to 8 of the S1 byte are used to
carry the synchronization messages of the SDH device.
1. This byte is only defined for the first STS-1/STM-1 frame of a composite signal.