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Re: snmpconf PM MIB issue #6 CLOSED - counter32Delta and counterRate



Hi Bob,

Thank you for the speedy response.

> I'm not talking about counter wraps -- I'm talking
> about discontinuities as they're defined in SMI.

Ah hah!  Was lost in counter wrappin' land.  Now I understand.

> Back in the beginning (actually before I became
> involved with SNMP, so somebody can correct me if
> I'm getting this wrong), the only discontinuity
> event recognized for a counter was reset of the
> SNMP agent.  So a manager was supposed to retrieve
> sysUpTime along with counter values, and determine
> that there had not been an agent reset before
> doing a delta calculation.
> 
> Later, it was realized that counters could undergo
> discontinuities even when the entire SNMP agent
> did not have a reset.  Examples include subagent
> reset, resource reconfiguration, and resource
> deactivation/reactivation.  So additional objects
> were added to MIBs, to store the time at which a
> specific counter or set of counters last
> experienced a discontinuity.  Managers are
> supposed to check these discontinuity objects
> (as well as sysUpTime) before doing a delta
> calculation.  I'm just looking for some similar
> validation, before a script does a delta
> calculation, that the resulting delta value will
> be valid.

I don't know how you can do this automagically, given that it
does require MIB knowledge.  If your policy script is going to
depend upon a counter that might be affected by this kind of
discontinuity, then I think you're just going to have to code
around it.  Perhaps, though, Steve has some thoughts.

Cheers,

--
David Partain                  David.Partain@ericsson.com
Ericsson Radio Systems AB      Tel:    +46 13 28 41 44
Research and Innovation        Fax:    +46 13 28 75 67
P.O. Box 1248                  http://linlab.ericsson.se/~epkpart
SE-581 12  Linköping, Sweden