Correlated alarms

Overview

The NFM-P generates a correlated alarm when a fault condition on one object causes an alarm condition on another object. For example, if a port goes down, an alarm is generated for the port, which is the affected object. Each service that uses the port generates an alarm. The alarm information for the affected object includes the correlated alarms.

The NFM-P automatically promotes the severity of correlating alarms to match the severity of correlated alarms. For example, if a major correlating port alarm has one or more critical correlated service alarms, the NFM-P changes the severity of the correlated port alarm to critical. The correlating alarm cannot have a severity that is lower than the severity of the correlated alarms. However, the severity that is defined by a specific alarm policy takes precedence over the correlated severity. The NFM-P does not lower the severity of correlating alarms when correlated alarms are cleared.

Note: Alarm correlation does not affect the severity of HIP alarms, or alarms that originate from an external EM system.

When the event that initiates an affected object alarm is resolved and the alarm clears, the correlated alarms also clear. If a correlated alarm does not clear after the affected object alarm clears, the source of the correlated alarm is an event other than the initiating event. In this case, the alarm correlation is removed and the alarm is displayed in the dynamic alarm list.

Service and transport alarm correlation

The NFM-P provides limited service and transport alarm correlation. When an LSP goes out of service, the NFM-P generates an alarm for the LSP and a correlated alarm for each LSP path that is a child object of the LSP. The LSP alarm is listed as an aggregated alarm for each SDP that uses the LSP. An NFM-P operator can use the aggregated LSP alarm for SDP troubleshooting.

There may not be a direct relationship between an LSP and the SDPs that use the LSP. For example, when LDP over RSVP is the transport mechanism, the NFM-P does not correlate SDP alarms with LSP alarms.