Do you know your CATs? You may be curious if this is an article about our feline friends. Unfortunately, I am referring to a rather humdrum topic of network cables but an essential part of the IT world. It is easy to forget that the backbone and the heart of most data communication still relies on network cables even nowadays with wireless devices. Old-fashion yet reliable network cables still carry the heavy burden of connecting devices across most businesses.
For most, who have worked on computers or those who have plugged in a computer at one point, may be familiar with white, blue, and among other color spectrum of cables protruding out from your PC and leading to router or modem. These colorful lines are referred to ‘Ethernet’ cables and are the common cables used to connect modem, router, or LAN (Local Area Network) to another computer (via NIC – Network Interface Card). Although the network cables are not distinguishable to most (other than the exterior sleeve colors), not all Ethernet cables are equal. Let's take a high level view at some of the basic differentiators between the Ethernet cables.
The original Ethernet cable was designed to simply communicate between machines or devices through a single cable. The idea was to allow devices to talk to each other while having the flexibility to unplug and re-plug the connected devices without any special configuration to the actual network. This brilliant concept and innovation was the product of Mr. Robert (Bob) Metcalfe who was working for PARC (Palo Alto Research Center) under the Xerox company in 1973. The project developed with the goal of communicating laser printers (a Xerox invention) across a simple network.
So why was the technology named ‘Ethernet’? Ether is actually an Old French term from Latin which means ‘upper pure, bright air.’ It is believed to be a passive yet omnipresent. At the time, Mr. Metcalfe and his team thought the network idea was fascinating and similar to the Ether concept, thus the team decided to call their new invention ‘ether network’ or Ethernet.
The Missing CATs
As device network activity among businesses and even personal space took shape, a standardization of the Ethernet cable was form in 1985. Since the standardization of the cables, there have been numerous variation of the cables but the core technology is amazingly still the same as it was when invented in the early 1970s. Only variation and noticeable changes are the increase in data transmission speed, improved electromagnetic interference insulation, and robust bandwidth. The cables are differentiated as ‘category’ or CAT for short. The standardization recognizes the Ethernet cables as CAT3, CAT4, CAT5, CAT5e, CAT6, CAT6a, and CAT7.
If you caught on, CAT1 and CAT2 are not listed or recognized as part of the standards. TIA (Telecommunication Industry Association) decided to exclude CAT1 and CAT2 as they were not used for data communication (rather mostly for voice circuits). Thus TIA and the industry defines different categories of cables starting with CAT3 and up.
So what differentiates the cables? Let’s take a quick peek at each category.
Category 3 cable or CAT3 is the trail blazer of the computer data communication link/cabling. It became the standard and widely used during the early 1990s. This was the first dedicated data cable mass marketed although it still has voice communication capability. It is an unshielded twisted pair (UTP) cable that was capable of 10 Mbps of data transmission. Surprisingly CAT3 cables are still in use today for two-line telephone communications and limited functions.
Category 4 or CAT4 cables became available in the early to mid 1990s but was short lived due to quickly adopted and available CAT5 (see next paragraph). It was capable of faster speed (16 Mbps) compared to CAT3 and used the same UTP. It was mostly used in commercial buildings during the mid 1990s and has small installed based for aging office buildings. CAT4 is sometimes not listed as part of the standards due to its short lived usage in the industry.
Category 5 or CAT5 became the most popular and widely used Ethernet cable to date. CAT5 is a UTP cable and considered Fast Ethernet cable (up to 100Mpbs). In addition, CAT5 cables introduced the 10/100 Mbps speed to the Ethernet, which means that the cables can support either 10 Mbps or 100 Mbps speeds. This range allowed first backward compatibility which contributed to its popularity. With the rise of video transmissions and personal computers during the mid to late 1990s, CAT5 is and was the most commonly used Ethernet cable in the industry. CAT5 slowly deprecated in 2001.
The Category 5e or CAT5e, is an ‘enhanced’ version of CAT5 cable. CAT5e allows reduction of crosstalk or unwanted transmission of signals between data channels. In addition to the reduction in interference, CAT5 was first to have capability of the Gigabit Ethernet (1,000 Mbps). Bandwidth also increased with Cat5e cables, which can support a maximum bandwidth of 100 MHz. While CAT5 is still commonly used, CAT5e is the official successor. Similar to CAT5, CAT5e cables are backward compatible.
CAT6 was the first to be a ‘certified’ Gigabit Ethernet cable standard. While CAT5e is ‘capable,’ CAT6 was officially certified and approved for Gigabit speed with 250 MHz bandwidth. In addition to the certification, CAT6 cables are made with extra insulation and shielding to eliminate interference. CAT6 is also backward compatible.
Category 6a cable, or ‘augmented’ CAT6a, is an improved version of the CAT6 cable. CAT6e increases the speed by allowing 10,000 Mbps data transmission rates and also increasing bandwidth to 500 MHz (double compared to basic CAT6). However, CAT6e requires special handling ground connectors. Thus, is mostly used at large institution or companies requiring the increased speed and bandwidth.
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. Due to extra shielding, there are some limitation on flexibility and installation. However, the much improved speed and bandwidth capabilities are far reaching. CAT7 is a future proof network capable if one so desires. At least until its successor comes along.
While Ethernet cables may look similar from the outside, each set of cables of categories offer varying scale of capabilities from speed, bandwidth and insulation. Most cable manufacturer will have the category type stamped on the sleeves (that look like the expiration date on your milk carton). It will be subtle, but it is there if carefully examined. In any event, it is important to know which category of cables are the right fit for your needs. If value is of keen interest, you may want to invest in the readily available and proven CAT5e or CAT6. But if you are looking for the latest and greatest with means to future proof your network infrastructure, CAT7 may be worth a look. The key take away is that not all cables are the same among the litter of CATs aforementioned. So review, assess, and test your CATs as it will be part of your family for extended period of time. Meow.