Detect and predict duplex mismatches in NPM
One of the most common causes of performance issues on 10/100 or 100/1000 Mbit Ethernet links occurs when one port on the link operates at half-duplex while the other port operates at full-duplex.
- Log into the SolarWinds platform Web Console.
- Go to the node details view for the parent node of the interface you want to check for duplex problems.
- Consult the Possible Duplex Mismatches widget. If there are no errors, the widget is hidden.
The widget lists all duplex interfaces on the node, the percentage of transmit and receive errors, and the neighboring node and interface. If the neighboring interface or node is not monitored, the appropriate columns are empty.
The last column displays the duplex mode issue - Mismatch, or Unknown.
To be able to detect duplex mismatches, your nodes need to meet the following requirements:
- The nodes must be monitored.
- The nodes must be in the up state during the discovery.
- The nodes must support topology and be interconnected.
- Duplex of both devices must be identified as full or half.
The widget shows all duplex mismatches, not only 100% duplex mismatches. These are reported on by the Duplex Mismatch alert.
Possible Duplex Mismatch
If at least one of the link interfaces has the duplex mode defined as half or full, the widget helps you identify possible mismatches.
Possible duplex mismatches are visible in the duplex mode column as the Unknown duplex mode. They are identified in the following cases:
- If the switch port reports more than 0.5% receive or transmit errors.
- If the switch port reports CRC errors.
- If the switch port reports Late Collision errors.
How do I resolve mismatches?
To resolve a duplex mismatch, make sure your hardware is working, and unify the duplex mode configuration on neighboring interfaces.
Troubleshoot duplex mismatches
The Possible Duplex Mismatches does not display on Node Details view
If the widget does not display on the node details view, there might be a performance issue due to the amount of interfaces and topology connections. Check the following logs for mismatch information:
The Possible Duplex Mismatches widget does not display percentage of errors
- No statistical data for these interfaces.
- A performance issue connected with getting statistic information for the widget.