5.1.4 SNMP version preferences
The SNMP protocol itself has evolved over the years from version 1 to version 2(c) and now version 3, with increasing security capabilities (among others). NNMi can handle any or a mix of all versions in your network environment.
The first SNMP response NNMi receives for a particular node determines the communication credentials and SNMP version used by NNMi for communication with that node.
The SNMP version selection for a node plays a role in NNMi accepting traps from that node:
If the source node or source object of the incoming trap has been discovered by NNMi using SNMPv3, NNMi accepts incoming SNMPv1, SNMPv2c, and SNMPv3 traps.
If the source node or source object of the incoming trap has been discovered by NNMi using SNMPv1 or multiple SNMPv2cs, NNMi discards incoming SNMPv3 traps.
If these traps must be received, follow the procedure described in 21.8.1 Configuring NNMi to authenticate SNMPv3 traps for nodes that are either managed by using SNMPv2 or SNMPv1 or that are not discovered.
You specify the minimum level of SNMP version and security settings that are acceptable in each area of your network. The options for the SNMP Minimum Security Level field are as follows:
Community Only (SNMPv1 only)
NNMi attempts to communicate using SNMPv1 with the configured values for community strings, timeouts, and retries. NNMi does not try any SNMPv2c or any SNMPv3 settings.
Community Only (SNMPv1 or v2c)
NNMi attempts to communicate using SNMPv2c with the configured values for community strings, timeouts, and retries. If there is no response to any community string using SNMPv2c, NNMi attempts to communicate using SNMPv1 with the configured values for community strings, timeouts, and retries. NNMi does not try any SNMPv3 settings.
Community
NNMi attempts to communicate using SNMPv2c with the configured values for community strings, timeouts, and retries. If there is no response to any community string using SNMPv2c, NNMi attempts to communicate using SNMPv1 with the configured values for community strings, timeouts, and retries. If none work, NNMi tries SNMPv3.
No Authentication, No Privacy
For users with no authentication and no privacy, NNMi attempts to communicate using SNMPv3 with the configured values for timeouts and retries. If none work, NNMi tries users with authentication and no privacy followed by users with authentication and privacy, if necessary.
Authentication, No Privacy
For users with authentication and no privacy, NNMi attempts to communicate using SNMPv3 with the configured values for timeouts and retries. If none work, NNMi tries users with authentication and privacy.
Authentication, Privacy
For users with authentication and privacy, NNMi attempts to communicate using SNMPv3 with the configured values for timeouts and retries.