# Interfaces FAQ

## Frequently Asked Questions

**1. Based on what condition are interfaces listed as subinterfaces?**

Subinterfaces are listed based on two criteria:

1. When two or more IP Addresses have the same ifIndex in the same device. (You can check it in ipAdEntifIndex (.1.3.6.1.2.1.4.20.1.2) in RFC1213-MIB)
2. When two or more interfaces have the same IP address in the same device or different devices.

**2. Why are interfaces not rediscovered in my device?**

- Check whether the SNMP Credential is passed in the device.
- Check whether the ifTable returns an output in the MIB browser (Both Standalone and in OpManager).
- Check whether the SNMP service is running on the device.
- Check whether the device is up and running at the moment.
- Check whether the SNMP port is blocked.
- Check whether the communication between the monitoring agent and OpManager is intact or not, in case of agent-monitored device.
- Check whether the agent service is running in the end server, in case of agent-monitored device.

**3. Why is there no data collection at my interfaces?**

- Check whether the SNMP Credential is passed in the device.
- Check whether the ifTable returns an output in the MIB browser (Both Standalone and in OpManager).
- Check if the parent device is down, unmanaged, or in the dependent unavailable status.
- Check if the interfaces are unmanaged.
- Check if it is a subinterface.
- Check if the interface has been decommissioned in the environment or if the ifIndex is not valid.
- Check whether the interface counter has been changed from 32-bit to 64-bit.
- Check whether the Interface MIB has not been implemented in the device.
- Check whether the interfaces have been moved to idle/disabled status by Data Collection Manager (DCM).
- Check whether the communication between the monitoring agent and OpManager is intact or not, in case of agent-monitored device.
- Check whether the agent service is running in the end server, in case of agent-monitored device.

Know more about the [common data collection errors](https://www.manageengine.com/network-monitoring/kb/common-data-collection-errors.html#interface).

**4. Why are the interface traffic values displayed as zero?**

Check ifInOctects (.1.3.6.1.2.1.2.2.1.10) and ifOutOctects (.1.3.6.1.2.1.2.2.1.16) for the specified interface in the MIB Browser (RFC1213-MIB).

**5. Why do traffic values differ from the real-time interface values in my interface graphs?**

Traffic values are different in these Interface Graphs because data collection happened at a different time. When you check real-time traffic during the interface's next poll, you may find that the real-time traffic values and the interface graph values are the same.

**6. Why is there no data in my interface-related reports when there is data collection at my interfaces?**

Interface-related reports are based on an hourly table. You can check these reports after an hour from when these interfaces were added.