The following are a list of known issues seen with eHealth 6.3.2.x when using RPM to monitor Juniper devices.
(RPM = Real-Time Performance)
Jitter Definition for Juniper RPM Differs
Juniper RPM defines jitter as the difference between the maximum response time and the minimum response time for a group of pings (Jitter = Maximum Response Time). This jitter measurement may differ from that calculated by other devices.
Juniper RPM May Record Microsecond Response Times as 0
Juniper RPM records timestamps at the application layer. Therefore, response times include both network delay and router OS delay. This OS delay can add up to 20 milliseconds per router. Since NTP is only accurate within milliseconds, Juniper RPM may record microsecond response times as 0, since the delay time is less than the accuracy of the NTP
Juniper Routers and Destination Element Must Use Same NTP Server
For Juniper RPM to record one-way data (jitter-in and jitter-out) for a response path, the Juniper router and the destination element must use the same Network Time Protocol (NTP) server. If the source and destination elements do not use the same NTP server, RPM records round-trip data for that path.