Access Transport network servers network network network Figure 20.8 Network operations center. consolidated from distributed systems. The requirement of NOC to have a holistic view of the network makes data consolidation a critical activity. Analysis: Filtering of records and correlation of records are components in data analysis. From the large amount of data that gets consolidated, relevant information has to be captured by filtering out unnecessary infor- mation. When a trunk shows a trouble state, the basic debugging approach involves a check on the status of its associated nodes like the related links or the link interface units. Fixing the link might bring the trunk back to service. So trouble scenarios need to be analyzed against different patterns that can cause the event. The data also need to be correlated to get relevant information. For example, when the connection between a media gateway and a MSC in the network goes down when a new module is loaded in the media gateway, there are various events that are generated during this scenario. The MSC will generate logs showing connection time out, link down, and SO on and the media gateway in addition to connection logs will show the log with the module, which caused it to go down. So different OSS/BSS Functions logs needs to be filtered and correlated to identify the actual problem that needs to be fixed. Corrective action and maintenance: When analysis of data identifies a trou- ble condition that can be mapped to a predefined corrective action, then an event handling module will execute the steps to complete the corrective action. For the above example of media gateway failure during a new module load, the event or action handler will trigger the command on the media gateway to perform a module replace or fallback to the old module/load. An administrator can also execute commands to take corrective action for a trouble condition. Service providers aim in having minimal manual interven- tion for fixing trouble conditions. The actions can involve repair, 