6.4.5 Evaluating the auto-discovery rules (Rule-based discovery only)
If you see unexpected discovery results, re-evaluate the auto-discovery rules.
When NNMi discovery finds an address hint, it uses the first matching rule to determine whether to create a node. If no rules are matched, NNMi discovery discards the hint. The ordering number for auto-discovery rules determines the order in which the auto-discovery rule configuration settings are applied.
For each auto-discovery rule, check the following settings:
Discover Matching Nodes must be enabled for auto-discovery to occur for the rule.
Verify that the following settings are correct for the type of nodes you want discovered for the rule:
- Discover Any SNMP Device
- Discover Non-SNMP Devices
Remember that only routers and switches are discovered by default and non-SNMP nodes are not discovered. If Discover Any SNMP Device is enabled, NNMi discovers all SNMP devices. If Discover Non-SNMP Devices is enabled, NNMi also discovers non-SNMP devices. Enabling these settings without considering your environment can result in NNMi discovering more nodes than intended.
- Organization of this subsection
(1) IP address ranges
The IP address of a discovery hint must match an Include in rule entry in the IP address range list. If there are no included IP address ranges in an auto-discovery rule, then all address hints are considered a match. (For this case, see 6.3.1 Tips for configuring auto-discovery rules.) Additionally, the hint must not match any entry marked Ignored by rule. If all checks successfully match, this rule's configuration is used for handling the hint.
If there is no discovery of some devices you expected to discover, check your configured IP ranges to ensure that the IP addresses for those devices are included in a range and not ignored by a rule with a lower ordering number.
If you are discovering more devices than you want, modify the include ranges or add ignored ranges for the IP addresses of the devices that you do not want discovered. Also, determine if Discover Any SNMP Device is enabled.
(2) System object ID ranges
The system object ID (OID) from a discovery hint must match an Include in rule entry in the system object ID ranges list. If there are no included system object ID ranges in an auto-discovery rule, then all object IDs are considered a match. Additionally, the OID must not match any entry marked Ignored by rule. If all checks successfully match, this rule's configuration is used for handling the hint.
Use the system object ID ranges to either expand auto-discovery to include more than the default routers and switches, or to exclude specific routers and switches.
Each node must match both the IP address range and the system object ID range specified before it is discovered and added to the topology database.