Ethernet can send and receive signals using only 2 pairs (4 cores) of twin-stranded wires as the transmission medium. There are three standards in fast Ethernet using twisted pair as the transmission medium: 100base-tx, 100base-t2 and 100base-t4. Where: the 100base-t4 standard requires the use of all 4 pairs of lines for signal transmission, and the other two standards only require 2 pairs of lines. The 100 base-tx standard is the most popular in fast Ethernet, so when you buy a 100 Megabyte network of twin-stranded lines, don't use just two pairs of twin-stranded lines for a bit of a bargain. Three, four, five, and more than five types of twine are defined as four pairs in the U.S. cable standard (AWG), and all four pairs are required for communication in gigabit Ethernet. Therefore, there should be four pairs of wires in the standard five cables.