We recently experienced an issue with two of our Expressway (paired) whereas Prognosis was detecting frequent Zone Status alerts ("Warning" with cause of "ystems Unreachable" and ZonePeer Status alerts ("Failed" with a cause of "No Reponse from system"). These occurred over a period of serveral days, hourly at times. We failed to find any issues or impact on the two associated Expressway devices and engaged Cisco TAC for further investigation. They too, were unable to find any trace of why these zone related alarms were being detected, including while they were still occurruing. TAC has asked if we could provide them with more details as to how and where Prognosis is capturing this zone and zone peer status information. I know this is being done by https query or webscrape, but are you able to provide details as to what in particular Prognosis is calling on for information on the zones and zone peers, inparticular zone status and error cause? The condition has since cleared on it's own, but we are trying to get a better understanding of how to troubleshoot in the event of a re-occurence.
Prognosis retrieves those zone status and zone cause metrics directly from the Expressway web interface using the "web gatherer" component in Prognosis that can read in metrics from web pages via http.
The Server Performance dashboard in Prognosis should help to identify which resources are stretched leading up to when the "no response" and "unreachable" alerts occur. Below image shows how to select that Prognosis dashboard.