We found that data collection was not happening for many of the links. On checking Real Time
Performance on the interfaces on which the link was created we could see that RTP also was not working. The packets sent by the device for collecting data were captured for further analysis. On analyzing the packets we could see that device was returning NULL value and so giving the error NO SUCH NAME. Also we could see that the SNMP Version was SNMPV1 which is the reason Why device is giving NULL value and data collection was not happening.
For current solution SNMPCollectorDm has been restarted and data collection was happening fine.
On checking the SNMP version in which the device is added in U2000 it was seen that the device
Was added using SNMPV2c only. But on capturing packets it was showing as SNMPV1.On
Further analysis we found that the device was initially added using SNMPV1 and later the version
Was changed to SNMPV2c.But SNMPCollectorDm missed the notification topology has sent on
SNMP version change. So in memory it was still SNMPV1.
Its frequency very rarely, only when device SNMP version is changed. Due to this, causes data collection to stop of wrong SNMP version used.