Optical Transport Manager for PDH describes the failures diagnosed for each low-order element in the SDH network. Optical Transport Manager for PDH cross-correlates with Optical Transport Manager for SONET/SDH to calculate which root-cause problems are causing symptomatic events and creates notifications for the problem origin. The Optical Transport Manager uses the relationships in the topology to calculate the impact that a root-cause problem in one element has on the elements and services that are connected to, or depend on it.

When the Optical Transport Manager receives alarms that relate to connections to elements that it does not manage, the Optical Transport Manager performs special analysis to determine if a problem has occurred in the connected network. This is described in “Diagnosis of external failure” on page 80.

Protection Schemes on page 95 provides For detailed information about the protection schemes supported by the Optical Transport Manager.