Impact analysis has two components:
Impact correlation is the process by which alarm conditions are identified as being explained by a root cause. For example, a line failure in SONET/SDH may cause many path-level alarms. The Optical Transport Manager Analysis Server identifies events corresponding to these alarms as impacts of the underlying root cause.
Impact notification identifies those end-to-end circuits that are affected when underlying connections are down. There are no network alarms directly associated with the end-to-end connections that would otherwise indicate their operational status.