Performance degradation

Learn about some possible reasons for performance degradation on a directly attached local console connection involving the communications port.

The most likely reason for performance degradation is that the communication port is not running a buffered UART (Universal Asynchronous Receive/Transmit serial port chip). This can be verified in the Advanced settings for the serial port. You must verify the buffered UART is selected, and that the Receive Buffer setting is not set to the right-most setting.

If this attempt does not help and you suspect that there is a possibility that the PC might truly not have the buffered UART, slow the connection down between the PC and server. Depending on the operating system, you might have to change the registry, the DUN object, or the telephone book entry, or all three.

The problem with the unbuffered UART is that the high-speed connection inputs data to the UART faster than it can handle, which causes missed packets of data resulting in a 30-second retry. This can occur randomly, but becomes persistent. The slower speed reduces the exposure to an overrun of data and therefore, no more 30-second retries.