Determining what OID is being read

Question

Hi All!

Sorry, if the question has been asked before, but I could not find it in the doc,in the online help or doing a search of the forums.

In Orion Network Performance, version 7.7, I am trying to figure out how it calculates the various values. Particularly, I am interested in finding out what OIDs are read. I was told that it uses the Host Resource MIB, but obviously many of the values displayed are calculated and not part of the MIB (at least as far as I can see).

Also we are getting values that do no appear to make sense, so it would be helpful to know what OIDs are being read. Where can I find out which OID are being used.

Any help is greatly appreaciated.

Regards,

Jim Mohr

BK · Answer

The Host CPU poller will first try to poll the processor utilization using the Host Resource MIBs hrProcessorLoad  (1.3.6.1.2.1.25.3.3.1.2) column.  If the MIB is supported, then the column is read (one row for each reported CPU) and the values averaged.  If hrProcessorLoad is not supported, then Net-SNMP MIB variable, ssCpuIdle (1.3.6.1.4.1.2021.11.11.0) is tried.  If a response is received, the value is subtracted from 100 and saved as the CPU load.  A flag is then set marking this host as a Net SNMP Agent.

Next Memory is polled. If the node responded to the Host Resource MIB, hrMemorySize (1.3.6.1.2.1.25.2.2.0) is polled and used as the Total Physical Memory Size.  Finally, the hrSWRunPerfMem (1.3.6.1.2.1.25.5.1.1.2) column is retrieved and the amount of RAM being used by each process is added together to determine the used memory.  This will result in memory utilization greater than 100% if you have paged RAM out to disk.  By allowing the utilization to be larger than 100%, an administrator can measurement of how much the RAM is overcommitted.

If Net-SNMP was detected, then memTotalSwap(1.3.6.1.4.1.2021.4.3.0),  memAvailSwap (1.3.6.1.4.1.2021.4.4.0), memTotalReal (1.3.6.1.4.1.2021.4.5.0), memAvailReal (1.3.6.1.4.1.2021.4.6.0) are polled.  Used Memory is calculated as memTotalSwap – memAvailSwap + memTotalReal – memAvailReal.  For Total Physical Memory Size, the value of memTotalReal is used.

Hope this helps.

BK
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