Introduction
Prime fails to add a WLC or unable to add Controller in WCS
Scenario 1
WLC 5508 8.0.115 fails when add to prime 2.2: Unable to collect details neighbor device using Cisco Discovery Protocol. Posible cause :
SNMP request timed out. Verify device credentials and SNMP response speed from device. The SNMP credentials are corrects.
Capturing packets we see that the WLC responds snmp requests but prime does not know how interpret the responses and re-order them.
Solution
User resolved it by changing "Maximum VarBinds per Get PDU" from 30 to 15 in Administration > Settings > System Settings > SNMP Settings.
Scenario 2
I use WCS v6.0.132.0 to manage my 4402 and 2106 controller both running version 6.0.182.0
When I try to add another 2106 over DM-VPN it fails with the following errors:
”No response from device, check SNMP communities, version or network for issues”
If I move the new 2106 controller to LAN with same config there is no problem.
I found this note in the in “Cisco Wireless Control System Configuration Guide, Release 6.0”
“Note If you are adding a controller into WCS across a GRE link using IPsec or a lower MTU link with multiple fragments, you may need to adjust the MaxVar Binds PerPDU. If it is set too high, the controller may fail to be added into WCS. To adjust the MaxVarBindsPerPDU setting, do the following:
1) Stop WCS.
2) Go to the location of the Open SnmpParameters.properties file on the server that is running WCS.
3) Edit MaxVarBindsPerPDU to 50 or lower.
4) Restart WCS.”
On my system I have the “SnmpParameters.properties” file is located //WCS6.0.132.0\webnms\classes\com\cisco\server\resources
But I don’t have “MaxVarBindsPerPDU” settings in the file.
Beside some # explanations text, the only settings I have in the “SnmpParameters.properties” file is:
DebugEnabled false
SerializeRequests true
MaxRepetitions 10
MaxRetryTimeout 60
WlanTimeoutMsecsPerAP 50
I have tried to add “MaxVarBindsPerPDU” settings, but it have no effect.
Solution
User resolved the issue by changing the “Maximum VarBinds per Get PDU” from 30 to 20 and “Maximum VarBinds per Set PDU” from 50 to 20.
More Information
If you are adding a controller into Prime Infrastructure across a GRE link using IPsec or a lower MTU link with multiple fragments, you might need to adjust the Maximum VarBinds per Get PDU and Maximum VarBinds per Set PDU. If it is set too high, the controller might fail to be added into Prime Infrastructure. To adjust the Maximum VarBinds per Get PDU or Maximum VarBinds per Set PDU, do the following: Stop Prime Infrastructure, choose Administration > Settings > SNMP Settings, and edit the Maximum VarBinds per Get PDU and Maximum VarBinds per Set PDU values to 50 or lower.
If you reduce the Maximum VarBinds per Get PDU or Maximum VarBinds per Set PDU value, applying the configurations to the device might fail.
Source
