What type of errors cause the Catalyst 3900 to switch to store-and-forward?
A. The decision to transition between cut-thru and store-and-forward when a port is configured for “auto” is based on the percentage of errored frames to all frames seen on that port during the sampling interval. Errored frames are: • Frames with CRC errors • Aborted frames • Frames that are too short At the end of a sampling interval, a calculation is done to determine the percentage of these errored frames to all frames seen on the port. If the resulting percentage is greater than the “error high threshold”, the port goes to store-and-forward mode. If the percentage is lower than the “error low threshold”, the port goes to cut-thru mode. The sampling interval, the error high threshold, and the error low threshold are all configurable on the Port Configuration panel.
