Port statistics and errors such as Received Fragments, CRC Error, Collisions, and normal port statistics such as packets and bytes received and transmitted can be reset to zero from the command line interface (CLI) serial port or through a Telnet session using the administrator password. Counters cannot be reset from the Web interface.
To effectively diagnose network problems these statistics may indicate, reset a port's statistics counters to zero and record the time of the reset so that the rate of a given statistic can be determined over a specified time period. For example, zero the port counter using the appropriate clear command and record the time Five minutes later use the appropriate show command to view the new value of the counter. This will give you an error rate. In general, the errors reported over a period of time should be very low in number (which can be due to occasional electromagnetic interference), or zero indicating the port is not at fault, however additional readings may need to be taken over a longer period of time to get a better sample. If a counter has a continuous rate of errors such as CRC errors, this may be due to a bad cable or faulty port.
The following are definitions of the Errors to watch for: