This counts B1 section-layer BIP-8 parity errors detected on this SONET/SDH port since the last counter reset. Because B1 errors are detected at the section layer, the lowest SONET/SDH overhead layer, a rising count here on this specific port usually points to a physical-layer or regenerator-level problem closest to the port itself, before the signal even reaches the line or path layers. A steadily increasing pportBipSectionErrors on this port with clean line and path BIP counters would isolate a fault to the immediate section between this port and the nearest regenerator or first hop.