VeEX MPA, User Manual

Page: 799 / 842

Term Definitions
799
Administrative Unit - Loss of Pointer (SDH only). In the Quick Status LEDs area, an
alarm LED indicating a consecutive number of invalid pointers or NDFs were received
on the AU.
B
B1 byte
RS Bit interleaved parity code (BIP-8) byte. This is a parity code (even parity) used to
check for transmission errors over a Regenerator Section. Its value is calculated over all
bits of the previous STM-N frame after scrambling, and then placed in the B1 byte of
STM-1 before scrambling. Therefore, this byte is defined only for STM-1 number 1 of an
STM-N signal.
B2 byte
Multiplex Section (MS) bit interleaved parity code (MS BIP-8). This bit interleaved parity
N x 24 code is used to determine if a transmission error has occurred over a multiplex
section. It's even parity and is calculated overall bits of the MS Overhead and the STM-
N frame of the previous STM-N frame before scrambling. The value is placed in the
three B2 bytes of the MS Overhead before scrambling. These bytes are provided for all
STM-1 signals in STM-N signals.
B3 byte
Path bit interleaved parity code (Path BIP-8) byte. This is a parity code (even) used to
determine if a transmission error has occurred over a path. Its value is calculated over
all the bits of the previous Virtual Container before scrambling and placed in the B3 byte
of the current frame.
B1 ERR
B1 Error. Indicates an error in the SONET frame. B1 errors are parity errors. The B1
byte carries the parity information, so a B1 error is a Section error that applies not only
to the Section OH, but the entire frame. Any error in the frame will result in a B1 error. A
B1 error is also known as a Section BIP-8.
B2 ERR
B2 Error. A B2 error is also known as a Line BIP-8. Indicates the number of parity errors
detected at the Line layer of the incoming SONET signal. This is calculated over the
Line OH, Path OH, and payload of each STS-1.
B3 ERR
MPA_e_manual_D07-00-129P_RevA00