VeEX MPA User Manual page 505

MPA_e_manual_D07-00-129P_RevA00
Protocol Tabs
The B3 byte of the Higher-Order Path Overhead is used to detect parity errors at the
Higher-Order Path layer of the incoming SDH signal. A B3 error is also known as a
Higher-Order Path BIP-8.
B3 errors are only reported by SDH equipment at each end of a SDH path. This broad
reporting means that an error may exist anywhere in the SDH path. The causes of a B3
error are similar to those attributed to B1 and B2 errors (faulty transmit and receive
equipment, a low receive signal, or dirty fibers) with the additional element of faulty Path
Terminating Equipment.
The first step in troubleshooting a B3 error is to look for B1 or B2 errors along the SDH
Higher-Order Path. If these errors exist, then there may be a problem with fibers or the
transmit or receive equipment along the SDH path. If these errors are not present, then
there may be a problem with the Path Terminating Equipment.
Related Topics:
Unit reports Loss of Signal (LOS)
What causes a B1 error?
What causes a B2 error?
What causes a B3 error?
What causes an AIS alarm?
What causes an RDI alarm?
How to Insert Errors
How to Insert Alarms
What Causes an AIS Alarm?
An Alarm Indication Signal (AIS) is an alarm sent to downstream network elements
(NE). It indicates that a defect has been reported by an upstream NE. If an NE has an
alarm condition, such as a Loss of Signal (LOS), Loss of Frame (LOF), or Loss of
Pointer (LOP), it generates an AIS to alert downstream NEs of an upstream failure.
The MPA supports the detection and transmission of Multiplex Section AIS (MS-AIS)
and STS Administrative Unit AIS (AU-AIS) alarms.
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