What does the Spectrum ?SNMP GET_NEXT LOOP DETECTED? alarm mean?

Document ID : KB000057368
Last Modified Date : 14/02/2018
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QUESTION: What does the Spectrum “SNMP GET_NEXT LOOP DETECTED” alarm mean?

 

ANSWER: The Probable Cause for the “SNMP GET_NEXT LOOP DETECTED” alarm states the following:

“Spectrum has attempted to parse through the MIB table and has detected an OID loop.”

This issue occurs when Spectrum is reading a MIB table and detects an instance read previously has been read again.

For example, Spectrum is running a getnext through a table that is indexed “1, 2, 3…”. Spectrum reads instance 1 and then does a getnext to read instance 2 and then does a getnext to read instance 3 and then does a getnext and the table returns instance 1 again. If Spectrum detects the next read is from an instance it has already read, this alarm is triggered and Spectrum will stop reading the table before it gets into a continuous loop reading the table.

The event id associated with alarm is the 0x10c17 event which reads as follows:

 

{d "%w- %d %m-, %Y - %T"} - An infinite loop has been detected in the MIB while reading oid {S 1}. Spectrum will not continue reading the table. (event [{e}])

 

You will notice in the above event, the mib "oid {S 1}" is where the loop was detected and printed in the associated event. As stated in the event, Spectrum will not continue reading the table.

 

The recommended actions as listed in the associated Probable Cause of the alarm are as follows:

 

RECOMMENDED ACTIONS:

1) Ignore this loop unless you suspect it will have a negative impact on other applications that you have running.

2) This is a loop in the MIB structure of the device being modeled. There will be no adverse effects on Spectrum itself as the software has identified this loop.

 

The hardware vendor should also be notified of the loop.