If auto-negotiation fails, your system can match the line speed of its link partner.
However, the adapter cannot sense the duplex mode. The system will use the default setting of half duplex, which can result in a duplex mismatch.
Here is an example of duplex mismatch.
Your System i™ platform, configured for full duplex, is connecting to a hub configured for half duplex. Your system begins sending information to the hub, which is waiting to receive. When the receive line is clear, the hub then begins transmission back to your system. During this transmission, your system receives the incoming data and (if it has data ready) begins transmitting to the hub. Because the hub is half duplex, it sees this unexpected receipt of data and cancels the transmission in progress. This is called a collision. A duplex mismatch problem might be reported as a failure-to-connect error, or it might cause a more subtle performance problem due to intermittent canceled frames.
Related concepts
Duplex mode Auto-negotiation