After the MPLS network is deployed and the service is up and running, it's important to monitor performance. Nodes can become faulted or congested, which can have a direct impact on the underlying services. Because this in turn can affect the conformance to SLAs by the SP, resulting in possible financial penalties, performance monitoring is increasingly important. Performance data can be acquired in a number of ways:
Polling MIB objects
Receiving threshold crossing events (for example, counters that reach preset levels)
Real-time collection via trend analysis of selected managed objects
Similar to accounting, performance data is of interest to both the NMS and OSS layers.