AltostratusGTM - Metric Timers
Can someone that is really familiar with GTM LS metrics help me understand the difference between these configuration settings. Their descriptions and default seconds seems to overlap/conflict.
Paths TTL - 2400s - number of seconds GTM considers path data valid
Inactive Path TTL - 604800s - number of seconds path remains in GTM cache after last access
Metrics Caching - 3600s - number of seconds which GTM dumps path and other metrics data
Inactive LDNS cache TTL - 2419200s - numer of seconds that inactive LDNS remains in GTM
If we were to go by descriptions alone and take an example metric of RTT. Path TTL would seem to say how long the RTTs are valid for consideration in LB determination - so 2400s by default. However, after the path TTL timer, the RTTs would remain on the GTM cache for which? the inactive path ttl like it says, so until the 604800 expires? If the answer is yes, then the inactive path ttl value would seem to never come into play because of the other setting - Metrics Caching - which says that all path metrics will be removed from BGP after 3600s. So, we would never reach the inactive path TTL time because the metric-cache would be removed way before the inactive paths ttl. So, the inactive paths ttl would seem irrelevant/redundant as it would seem to never be used because of the metric-caching timer would be reached way before.
