Cat 3 cable was only capable of carrying data at speeds of up to 10 megabits per second. Cat 5 cable has replaced cat 3 cable, as it supports data at speeds of 100 mbps or more. Cat 5e is enhanced cat 5 cable. It supports 1000 mbps. Therefore, it is replacing ordinary cat 5 cable. The category number is stamped on the outer sheath of cable, which allows you to identify a length of cable as being cat 3, cat 5, or cat 5e.