Snmpcollecotor - Availability and Reachability differences.
What is difference and how are these calculated ?
Both Availability and Reachability are generated using the sysUpTime returned from the device. How each of these uses sysUpTime is slightly different.
Compares the sysUpTime to the time since the last poll. If sysUpTime > time since the last poll, then it returns 100 as QoS data, it means device is up in between 2 polls.
If it's less, it returns 0 as QoS data, it means that device is restarted in between 2 polls.
If polling to the target device is not successful by any reason, it simply does not generate any QoS data.
If sysUpTime of the target device is accessible, it simply returns 100 as QoS data.
If polling to the target device is not successful by any reason, or if it simply does not return a sysUpTime, then it shows 0 as QoS data as soon as the device can not be contacted.
It simply means that the device is not reachable in the poll.
The difference in the way these use sysUpTime means that it's possible for some graphs to appear mismatched.