It’s great that Check_MK can warn when a network interface / switch port lowers its interface speed, as this probably indicates a broken cable. However, I don’t quite see the advantage of warning on a higher interface speed than was expected. This is especially true when the stored/expected speed is 0, since this probably means the port was down and that probably caused a critical state for the check anyway.
So in addition to the “Ignore speed” option, I would love to have an “Ignore higher speed” option, which ideally even stores the higher speed so that it is the expected speed in future check executions.