To diagnose a fault or error condition on a routing platform, you need relevant information about the state of the platform. You can derive state information from event notifications. Event notifications are system log messages and Simple Network Management Protocol (SNMP) traps. A JUNOS software process called the event process (eventd) receives event notifications—henceforth simply called events— from other JUNOS software processes.
Timely diagnosis and intervention can correct error conditions and keep the routing platform in operation. After the eventd process receives events, event policies instruct the eventd process to select specific events, correlate the events, and perform a set of actions. These actions can either help you diagnose a fault or take corrective action. For example, the eventd process can upload routing platform files to a given destination and issue operational mode commands.
Events can originate as SNMP traps or system log messages. The event process receives event messages from other JUNOS processes, such as the routing protocol process (rpd) and the management process (mgd). Depending on the custom event policy you configure, eventd listens for specific events and in response to these events might create log file, invoke a JUNOS command, or invoke an event script. When an event script is invoked, event details are passed to the event script in the form of XML inputs.
Figure 11 shows how the event process (eventd) interacts with other JUNOS software processes.
Figure 11: Eventd Process Interaction with Other JUNOS Software Processes
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