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The types of network cables employed in any network infrastructure is one of the most important aspects of networking, and it has become increasingly critical with the introduction of newer technologies, such as blade servers, virtualization, network storage devices, wireless access points and more.
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Network services, like file sharing, internet access, network printing, email, ERP systems and more, are all delivered to end users via the network infrastructure, which usually includes switches, fiber optic links and, underpinning it all, unshielded twisted pair (UTP) cabling.
This series will focus on the different types of network cables, such as Ethernet copper cabling specifications, speeds and caveats of each technology.
We'll continue with the expansion of our covered topics to include fiber optic technology and talk about the different fiber optic cables available in the market. Then, we'll jump back into the past by covering various direct cable connections used to transfer data between computers. The last section will cover in detail serial, parallel and USB ports, and their different specifications or versions. Plus, we'll talk about the types of network cables used to connect between these old technology ports.
While many might believe the last section of this series may contain information that is not considered useful -- serial, parallel and USB ports -- you'll be surprised to find out how much of this information will actually come in handy in the future.
All material covered in this series includes detailed diagrams and has been checked to ensure it is as accurate as possible.
Types of network cables: A history
We tend to think of digital communication as a new idea, but in 1844, Samuel Morse sent a message 37 miles -- from Washington, D.C., to Baltimore -- using his new invention, the telegraph. This may seem a far cry from today's computer networks, but the principles remain the same.
Morse code is a type of binary system that uses dots and dashes in different sequences to represent letters and numbers. Modern data networks use ones and zeros to achieve the same result. The big difference is, while the telegraph operators of the mid-19th century could perhaps transmit four or five dots and dashes per second, computers now communicate at speeds of up to 10 Gbps -- or, to put it another way, 10,000,000,000 separate ones and zeros every second.
Although the telegraph and the teletypewriter were the forerunners of data communications, it has only been in the last 35 years that things have really started to speed up. This was borne out of the necessity for computers to communicate at ever-increasing speeds, which has driven the development of faster and faster networking equipment. In the process, higher-specification cables and connecting hardware were required.
Development of new network cable technology
Ethernet was developed in the mid-1970s by Robert Metcalfe and David Boggs at Xerox Corp. at its Palo Alto Research Center in California. In 1979, DEC and Intel joined forces with Xerox to standardize the Ethernet system. The first specification by the three companies, called the Ethernet Blue Book, was released in 1980; it was also known as the DIX standard after the company's initials.
That standard called for speeds of up to 10 Mbps system -- 10 Mbps equals 10 million ones and zeros per second -- and relied on a large coaxial backbone cable running throughout the building, with smaller coax cables tapped off at 2.5-meter intervals to connect to the workstations. The large coax, which was usually yellow, became known as Thick Ethernet, or 10BASE5. In the latter term, the 10 refers to the speed -- 10 Mbps; BASE is used because it is a baseband system -- baseband uses all of its bandwidth for each transmission, as opposed to broadband, which splits the bandwidth into separate channels to use concurrently; and the 5 refers to the system's maximum cable length -- in this case, 500 meters.
In 1983, the IEEE released the official Ethernet standard. It was called IEEE 802.3, after the name of the working group responsible for its development; in 1985, version 2 (IEEE 802.3a) was released. This second version is commonly known as Thin Ethernet or 10Base2; in this case, the maximum length is 185 meters, even though the 2 suggests it should be 200 meters.
Since 1983, various standards have been introduced, and thanks to the evolution and growth of applications and new technologies, we have reached speeds of 10 Gbps, while new standards are being developed to push these limits for copper-based cabling well beyond the 10 Gbps barrier.
Unshielded twisted pair
UTP cable is certainly the most popular type of network cable by far around the world. UTP cable is used not only for networking, but also for the traditional telephone (UTP-CAT1). There are six different types of UTP categories and, depending on what you want to achieve, you would need the appropriate type of network cable. UTP-CAT5e is the most popular UTP cable; it replaced the old coaxial cable that was unable to keep up with the constantly growing need for faster and more reliable networks.
Characteristics of UTP categories
The characteristics of UTP are very good and make it easy to work with, install, expand and troubleshoot. Now, we are going to look at the different wiring schemes available for UTP, how to create a straight-through UTP cable, rules for safe operation and a lot of other interesting information.
So, let's have a quick look at each of the UTP categories available today:
These categories specify the type of copper wire -- most telephone and network wire is copper -- and jacks. The number (1, 3, 5 and so on) refers to the revision of the specification and, in practical terms, to the number of twists inside the wire -- i.e., to the quality of connection in a jack.
CAT1 is typically used for telephone wire. This type of wire is not capable of supporting computer network traffic and is not twisted. CAT1 is also used by telco companies providing Integrated Services Digital Network and public switched telephone network services. In such cases, the wiring between the customer's site and the telco's network is performed using CAT1-type cable.
CAT2, CAT3, CAT4, CAT5/5e, CAT6 and CAT7 are network wire specifications. These types of wires can support computer network and telephone traffic. CAT2 is used mostly for token ring networks and supports speeds up to 4 Mbps. For higher network speeds -- 100 Mbps or higher -- CAT5e must be used. For the almost-extinct 10 Mbps speed requirements, CAT3 will suffice.
CAT3, CAT4 and CAT5 cables are four pairs of twisted copper wires; CAT5 has more twists per inch than CAT3. Therefore, CAT5 can run at higher speeds and greater lengths. The twist effect of each pair in the cables ensures any interference presented or picked up on one cable is cancelled by the cable's partner that twists around the initial cable. CAT3 and CAT4 are both used for token ring networks -- where CAT3 can provide support of a maximum 10 Mbps, while CAT4 pushed the limit up to 16 Mbps. Both categories have a limit of 100 meters.
The more popular CAT5 wire is now replaced by the CAT5e specification that provides improved crosstalk specification, allowing it to support speeds of up to 1 Gbps. CAT5e is the most widely used type of network cabling specification worldwide, and unlike the category cables that follow, it is very forgiving when the cable termination and deployment guidelines are not met.
CAT6 wire was originally designed to support Gigabit Ethernet, although there are standards that will allow gigabit transmission over CAT5e wire. It is similar to CAT5e wire, but contains a physical separator between the four pairs to further reduce electromagnetic interference. CAT6 is able to support speeds of 1 Gbps for lengths of up to 100 meters, and 10 Gbps is also supported for lengths of up to 55 meters.
Today, most new cabling installations use CAT6 as a standard; however, it is important to note that all cabling components -- jacks, patch panels, patch cords and the like -- must be CAT6-certified, and extra caution must be given to the proper termination of the cable ends.
In 2009, CAT6A was introduced as a higher specification cable, offering better immunization from crosstalk and electromagnetic interference.
Organizations performing installations using CAT6 cabling should request a thorough test report, using a certified cable analyzer, to ensure the installation has been performed according to CAT6 guidelines and standards.
CAT7 is a newer copper cable specification designed to support speeds of 10 Gbps at lengths of up to 100 meters. To achieve this, the cable features four individually shielded pairs, plus an additional cable shield to protect the signals from crosstalk and electromagnetic interference.
Due to the extremely high data rates, all components used throughout the installation of a CAT7 network cabling infrastructure must be CAT7-certified. This includes patch panels, patch cords, jacks and RJ-45 connectors. The absence of CAT7-certified components will degrade overall performance and thus lead to the failure of any CAT7 certification tests -- for example, using a cable analyzer -- since CAT7 performance standards are most likely not to be met. Today, CAT7 is usually used in data centers for backbone connections between servers, network switches and storage devices.
Cabling series, lesson 2: Straight-through UTP cables
Cabling series, lesson 3: CAT5 UTP crossover cable
Cabling series, lesson 4: 10Base-T/2/5/F/35 - Ethernet
Dig Deeper on Ethernet
Chris Partsenidis asks:
Which types of networking cable does your organization use?
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