This is a count of the total number of bytes transmitted by the port in good and bad packets. The count includes the 4 CRC bytes but does not include the preamble or SFD bytes. Bad packets include normal collisions, late collisions, and FIFO underflows. For collisions, all bytes transmitted before the start of the collision as well as the colliding and jam bytes are counted. For FIFO underflows, all bytes actually transmitted are counted.