Ethernet cables have been evolving since the beginning of the Ethernet standard in 1985. Many different categories of Ethernet cable have been developed, and each category has different specifications as far as shielding from electromagnetic interference, data transmission speed, and the possible bandwidth frequency range required to achieve that speed. The standard gauge sizes (AWG) are also differences in the different categories of cable, and this can have end results in both quality and speed.
Category 3 Ethernet cable, also known as Cat3 or station wire, is one of the oldest forms of Ethernet cable still in use today. It is an unshielded twisted pair (UTP) cable that is capable of carrying 10 Mbps of data or voice transmissions. Its maximum possible bandwidth is 16 MHz. Cat3 cable reached the peak of its popularity in the early 1990s, as it was then the industry standard for computer networks. With the debut of the faster Category 5 cable, however, Cat3 fell out of favor. It still can be seen in use in two-line telephone systems and older 10BASE-T Ethernet installations.
Category 5 (Cat5) Ethernet cable is the successor to the earlier Category 3. Like Cat3, Cat5 is a UTP cable, but it is able to carry data at a higher transfer rate. Cat5 cables introduced the 10/100 Mbps speed of the Ethernet, which means that the cables can support either 10 Mbps or 100 Mbps speeds. A 100 Mbps speed is also known as Fast Ethernet, and Cat5 cables were the first Fast Ethernet-capable cables to be introduced. They also can be used for telephone signals and video, in addition to Ethernet data. This category has been superseded by the newer Category 5e cables.
Category 5e (Cat5e) standard is an enhanced version of Cat5 cable, which is optimized to reduce crosstalk, or the unwanted transmission of signals between data channels. This category works for 10/100 Mbps and 1,000 Mbps (Gigabit) Ethernet, and it has become the most widely used category of Ethernet cable available on the market. While Cat5 is common in existing installations, Cat5e has completely replaced it in new installations. While both Cat5 and Cat5e cables contain four twisted pairs of wires, Cat5 only utilizes two of these pairs for Fast Ethernet, while Cat5e uses all four, enabling Gigabit Ethernet speeds. Bandwidth is also increased with Cat5e cables, which can support a maximum bandwidth of 100 MHz. Cat5e cables are backward-compatible with Cat5 cables, and can be used in any modern network installation.
One of the major differences between Category 5e and the newer Category 6 (Cat6) is in transmission performance. While Cat5e cables can handle Gigabit Ethernet speeds, Cat6 cables are certified to handle Gigabit Ethernet with a bandwidth of up to 250 MHz. Cat6 cables have several improvements, including better insulation and thinner wires. These improvements provide a higher signal-to-noise ratio, and are better suited for environments in which there may be higher electromagnetic interference. Some Cat6 cables are available in shielded twisted pair (STP) forms or UTP forms. However, for most applications, a Cat5e cable is adequate for Gigabit Ethernet. The Cat5e is also much less expensive than Cat6 cable. Cat6 cable is also backward-compatible with Cat5 and 5e cables.
Category 6a cable, or augmented Category 6 cable, improves upon the basic Cat6 cable by allowing 10,000 Mbps data transmission rates and effectively doubling the maximum bandwidth to 500 MHz. Category 6a cables are usually available in STP form, and, as a result, must have specialized connectors that ground the cable.
Category 7 cable (Cat7), also known as Class F, is a fully shielded cable that supports speeds of up to 10 Gbps (10,000 Mbps) and bandwidths of up to 600 MHz. Cat7 cables consist of a screened, shielded twisted pair (SSTP) of wires, and the layers of insulation and shielding contained within them are even more extensive than that of Cat6 cables. Because of this shielding, they are thicker, bulkier, and are more difficult to bend. Additionally, each of the shielding layers must be grounded, or else performance may be reduced to the point that there is no improvement over Cat6. In fact, performance may be even worse than Cat5. For this reason, it is very important to understand the type of connectors at the ends of a Cat7 cable.
The following table summarizes the most common types of Ethernet cables, including their maximum data transmission speeds and maximum bandwidths:-
|Category Type||Speed||Detailed Information|
|Category 5||10/100/1000MbE*||Category 5 cable is a currently outdated standard that provides support for up to 100Mhz operation. It can be used for 10/100 Ethernet .|
|Category 5e||10/100/1000MbE||Category 5e cable provides support for frequencies up to 100Mhz. Cat. 5e generally provides the best price for performance.|
|Category 6 is defined up to a frequency of 250Mhz. Allowing 10/100/1000 use with up to 100 meter cable length, along with 10GbE over shorter distances.|
|Cat. 6a or Augmented Category 6 is defined up to 500Mhz. It allows up to 10GbE with a length up to 100m.|
|Category 7 is the informal name for "Class F" cabling defined by a different standards body than Cat. 6a and lower. It supports frequencies up to 600Mhz and may support the upcoming 100GbE standard|