What does ODUk_PM_BDI indicate?

ODUk_PM_BDI refers to the ODUk PM backward defect indication. It is a monitoring signal used in OTN to indicate that a defect has been detected downstream (toward the transmitter side). When this indication is received, it informs the upstream node of the presence of defects or faults, allowing timely protection switching or troubleshooting. This mechanism supports fault propagation awareness across network segments, essential in maintaining service integrity. HCIP-Transmission details this indicator as part of ODUk performance monitoring (PM) overhead functions to enhance network reliability and fault management.