First of all I wanted to take a moment to explain what this message means as it is one of the comman issue's with 6500s:
This message just means that the SNMP queue is full and hence some packets are being dropped.
Depending on the amount of data being polled, this is completely expected since SNMP is very low priority as it is just a monitoring tool.
If too much SNMP traffic is building up, the device will drop these packets over any other more important data such as routing-switching traffic.
Here are some basic steps to troubleshoot this issue:
1. There are known issues reported on 6500s. I have seen a lot of issue with 6500s and the CISCO-FLASH-MIB. A common workaround is to do a view to exclude this MIB.
This is easy to do, the commands are the following:
snmp-server view public-view ciscoFlashMIB excluded
snmp-server view public-view ciscoSwitchEngineMIB excluded
Now you have to remove your current community and have update them as per the view (change the <removed> with the community string configured)
no snmp-server community <removed> view public-view RO
no snmp-server community <removed> RO
snmp-server community <removed> view public-view RO
snmp-server community <removed> view public-view RO
2. Besides the common issues with the CISCO-FLASH-MIB is saw bugs such as CSCte66495 .
You can access the bug details at the link below:
http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCte66495
Even though the bug description does not directly mentions the "%SNMP-3-INPUT_QFULL_ERR" message, but the issue is related to the error message. So, in many cases it is been observed that after upgrading to a fixed version, or implemented the workaround the "%SNMP-3-INPUT_QFULL_ERR” disappeared.
3. Another bug that seems to be related to this message is CSCtn19200 .
Bug details can be seen below:
http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCtn19200
4. To be more certain of what exactly is the problem, we would have to
collect a 'show stacks <snmp-engine pid>' output, but based on the evidence I believe the best course of action is to either upgrade to the IOS versions that contains the fix for the bugs I mentioned or implement the workaround.
