Ethernet is a set of standards for the physical aspects of networks. The standards mention several types of cable, but the most commonly used cable in Ethernet networks is called Unshielded Twisted Pair. Because it is so frequently used in Ethernet networks, UTP is often referred to as "Ethernet cable." The manufacture of UTP cables follow standards that categorise them. These categories of UTP cables are indicated by a "Cat" number. Cat 5 and Cat 6 UTP cables are widely used in Ethernet networks.
Any company can manufacture cable. However, buyers need to know the capabilities of different types of cable, and so neutral standards were created as a shorthand for a list of specifications. These specifications are produced by the Telecommunications Industry Alliance. So far, the TIA has defined seven categories of UTP cable. There are Cat 1 to Cat 5, Cat 5e and Cat 6. Cat 5 and Cat 5e are encountered more frequently in current network implementations. Cat 6 is a newer cable type offering better performance and so is expected to become more common than Cat 5 and Cat 5e.
Unshielded Twisted Pair contains four pairs of wires. The two wires of each pair are twisted around each other for the entire length of the cable. Each pair is the positive and negative path of a complete circuit. The opposite charge of each protects the wires from interference. Because the wires are tightly packed each pair is wound at a different rate. This reduces the incidence of the pairs passing charge between each other. Both Cat 5 and Cat 6 UTP have exactly the same configuration.
The rate at which the pairs are twisted varies the cost of the wire. Winding the pairs with more frequent turns uses more wire. More tightly wound wires, however, are able to carry data faster and further because they have less impedance and susceptibility to interference. This is the key difference between Cat 5 and Cat 6 UTP cable. The Cat 6 cable has more turns, which costs more, but gives better performance. The two varieties of Cat 5 cable enable a throughput of 100 Megabits per second or 1,000 Megabits per second if four pairs of the bundle are employed instead of the usual two pairs. Cat 6 cable gives a throughput of 1,000 Megabits per second with two pairs but has greater potential for future improvement.
Use for Ethernet
Ethernet standards advance performance with each passing year and each new specification. The greater performance means that the latest high speed Gigabit Ethernet specifications cannot be achieved with Cat 5 cable, or its variant, Cat 5e. Ethernet standards have been well served by Cat 5 cable so far, but its performance barriers have been reached. This is why the passing years will see Cat 6 implementations outnumber Cat 5 usage.