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Black Box Explains...Token Ring Cabling

The original Token Ring specifications called for shielded twisted-pair (STP) cable using either a DB9 connector or a unique square connector called the IBM data connector. Later, Token Ring was... more/see it nowadapted to use conventional unshielded twisted-pair (UTP) cable with RJ-45 connectors. The most common kinds of Token Ring cabling in use to day are Type 1 and Type 6 STP as well as Type 3 UTP.

Type 1 shielded twisted-pair (STP) cable is the original wiring for Token Ring. In Type 1 cabling, each wire is constructed of 22 AWG solid copper. Type 1 cable is not as flexible as Type 6 cable and is generally used for long runs in areas where twists and turns are less likely, such as in walls or conduits.

Type 6 Token Ring cable is a lighter, more pliable version of Type 1 cable. It’s constructed of two stranded 26 AWG copper pairs that are surrounded by an overall braided shield. Type 6 cable is commonly used in offices and open areas, and its flexible construction enables it to negotiate multiple twists and turns.

Type 3 or UTP Token Ring cabling uses the same twisted-pair CAT3, CAT5, or CAT5e cabling with RJ-45 connectors as 10BASE-T Ethernet does. Attaching older Type 1 Token Ring to UTP Token Ring requires a balun or adapter. collapse


Black Box Explains...10-GbE, CAT6A, and ANEXT.

The IEEE released the 802.3an 10GBASE-T standard in June 2006. This standard specifies 10-Gbps data transmission over four-pair copper cabling. 10-Gigabit Ethernet (10-GbE) transmission includes up to 37 meters of... more/see it nowCAT6 cable (with installation mitigation techniques), 100 meters of Augmented Category 6 (CAT6A) UTP or F/UTP cable or 100 meters of S/FTP CAT7/Class F cable.

CAT6A is the ANSI/TIA 10-Gigabit Ethernet (10-GbE) over copper standard. Its requirements are covered in ANSI/TIA-568-C.2 (Balanced Twisted-Pair Communications Cabling and Components Standard) published in August 2009. It defines 10-Gigabit data transmission over a 4-connector twisted-pair CAT6A copper cable for a distance of 100 meters.

Category 6A cabling is designed to support next-generation applications, including the transfer of large amounts of data at high speeds, up to 10 Gbps. CAT6A extends electrical specifications to 500 MHz from 250 MHz for CAT6 cabling. CAT6A cables are fully backward compatible with previous categories, including CAT6 and 5e. Category 6A is also designed to support bundled cable installations up to 100 meters and PoE+ low-power implementations. The standard includes the performance parameter, Alien Crosstalk (ANEXT). Because of its higher performance transmission speeds and higher MHz rating, CAT6A cable needs to be tested for external noise outside the cable, which wasn’t a concern with previous cabling categories. CAT6A UTP also has a much larger diameter than previous cables.

Alien crosstalk (ANEXT) is a critical and unique measurement in 10-GbE systems. Crosstalk, measured in 10/100/1000BASE-T systems, is the mixing of signals between wire pairs within a cable. Alien Crosstalk, in 10-GbE systems, is the measurement of the unwanted signal coupling between wire pairs in different and adjacent cables or from one balanced twisted-pair component, channel, or permanent link to another.

The amount of ANEXT depends on a number of factors, including the type of cable, cable jacket, cable length, cable twist density, proximity of adjacent cables, and connectors, and EMI. Patch panels and connecting hardware are also affected by ANEXT.

With Alien Crosstalk, the affected cable is called the victim cable. The surrounding cables are the disturber cables.

There are a number of ways to mitigate the effects of ANEXT in CAT6A runs. According to the standards, ANEXT can be improved by laying CAT6A UTP cable loosely in pathways and raceways with space between the cables. This contrasts to the tightly bundled runs of CAT6/5e cable that we are used to. The tight bundles present a worst-case scenario of six cables around one, thus the center cable would be adversely affected by ANEXT. CAT6A UTP cable needs to be tested for ANEXT. This is a complex and time-consuming process in which all possible wire-pair combinations need to be tested for ANEXT and far-end ANEXT. It can take 50 minutes to test one link in a bundle of 24 CAT 6A UTP cables.

To virtually eliminate the problem of ANEXT, you can use CAT6A F/UTP cable. The F indicates an outer foil shield encasing four unshielded twisted pairs. This cable is also a good choice when security is an issue because it doesn’t emit signals. In addition, CAT6A F/UTP cable works well in noisy environments with a lot of EMI/RFI.

Installation of CAT6A F/UTP is simpler, too, because the cable features a smaller outside diameter than CAT6A UTP. Its construction makes it easier to pull and more resilient. The cable also has a smaller diameter so you can run more cables in a conduit or pathway, and have greater patch panel port density.

For more information, see the CAT6A F/UTP vs. UTP: What You Need to Know white paper in the Resources section at blackbox.com. collapse


Black Box Explains...MT-RJ fiber optic connectors.

Bringing fiber to the desktop is a great way to provide your users with increased bandwidth. The first step in achieving this goal is to provide an inexpensive fiber optic... more/see it nowsystem that is intuitive to the end user, easy to terminate in the field, and widely supported by equipment manufacturers. MT-RJ could be the answer to all these requirements.

A collaborative effort by leading fiber optic manufacturers, MT-RJ has an intuitive RJ latch that users recognize from copper Category 5 patch cords and traditional telephone cords, and it operates in the same way. The plug and jack are also similar in size to traditional RJ-type connectors.

Field installation, a common concern, is easier because of MT-RJ’s no-polish, no-epoxy, quick-termination design. MT-RJ is available in single- or multimode configurations and is backwards compatible for integration into existing networks. Since MT-RJ has duplex polarity, you don’t have to worry about the polarity reversal that happens with traditional ST type connectors. The TIA/EIA recently voted to accept MT-RJ, indicating wide acceptance of the new design and possible future inclusion in the TIA/EIA 568A standard.

Black Box, the name you trust to keep you up with the latest industry developments, supports this new technology. collapse


Black Box Explains...Category wiring standards

The ABCs of standards
There are two primary organizations dedicated to developing and setting structured cabling standards. In North America, standards are issued by the Telecommunications Industry Association (TIA),... more/see it nowwhich is accredited by the American National Standards Institute (ANSI). The TIA was formed in April 1988 after a merger with the Electronics Industry Association (EIA). That’s why its standards are commonly known as ANSI/TIA/EIA, TIA/EIA, or TIA.

Globally, the organizations that issue standards are the International Electrotechnical Commission (IEC) and the International Organization for Standardization (ISO). Standards are often listed as ISO/IEC. Other organizations include the Canadian Standards Association (CSA), CENELEC (European Committee for Electrotechnical Standardizations), and the Japanese Standards Association (JSA/JSI).

The committees of all these organizations work together and the performance requirements of the standards are very similar. But there is some confusion in terminology.

The TIA cabling components (cables, connecting hardware, and patch cords) are labeled with a ”category.” These components together form a permanent link or channel that is also called a ”category.” The ISO/IEC defines the link and channel requirements with a ”class” designation. But the components are called a ”category.”

The standards
Category 5 (CAT5) —ratified in 1991. It is no longer recognized for use in networking.

Category 5e (CAT5e), ISO/IEC 11801 Class D, ratified in 1999, is designed to support full-duplex, 4-pair transmission in 100-MHz applications. The CAT5e standard introduced the measurement for PS-NEXT, EL-FEXT, and PS-ELFEXT. CAT5e is no longer recognized for new installations. It is commonly used for 1-GbE installations.

Category 6 (CAT6) – Class E has a specified frequency of 250 MHz, significantly improved bandwidth capacity over CAT5e, and easily handles Gigabit Ethernet transmissions. CAT6 supports 1000BASE-T and, depending on the installation, 10GBASE-T (10-GbE).

10-GbE over CAT6 introduces Alien Crosstalk (ANEXT), the unwanted coupling of signals between adjacent pairs and cables. Because ANEXT in CAT6 10-GbE networks is so dependent on installation practices, TIA TSB-155-A and ISO/IEC 24750 qualifies 10-GbE over CAT6 over channels of 121 to 180 feet (37 to 55 meters) and requires it to be 100% tested, which is extremely time consuming. To mitigate ANEXT in CAT6, it is recommended that the cables be unbundled, that the space between cables be increased, and that non-adjacent patch panel ports be used. If CAT6 F/UTP cable is used, mitigation is not necessary and the length limits do not apply. CAT6 is not recommended for new 10-GbE installations.

Augmented Category 6 (CAT6A) –Class Ea was ratified in February 2008. This standard calls for 10-Gigabit Ethernet data transmission over a 4-pair copper cabling system up to 100 meters. CAT6A extends CAT6 electrical specifications from 250 MHz to 500 MHz. It introduces the ANEXT requirement. It also replaces the term Equal Level Far-End Crosstalk (ELFEXT) with Attenuation to Crosstalk Ratio, Far-End (ACRF) to mesh with ISO terminology. CAT6A provides improved insertion loss over CAT6. It is a good choice for noisy environments with lots of EMI. CAT6A is also well-suited for use with PoE+.

CAT6A UTP cable is significantly larger than CAT6 cable. It features larger conductors, usually 22 AWG, and is designed with more space between the pairs to minimize ANEXT. The outside diameter of CAT6A cable averages 0.29"–0.35" compared to 0.21"–0.24" for CAT6 cable. This reduces the number of cables you can fit in a conduit. At a 40% fill ratio, you can run three CAT6A cables in a 3/4" conduit vs. five CAT6 cables.

CAT6A UTP vs. F/UTP. Although shielded cable has the reputation of being bigger, bulkier, and more difficult to handle and install than unshielded cable, this is not the case with CAT6A F/UTP cable. It is actually easier to handle, requires less space to maintain proper bend radius, and uses smaller conduits, cable trays, and pathways. CAT6A UTP has a larger outside diameter than CAT6A F/UTP cable. This creates a great difference in the fill rate of cabling pathways. An increase in the outside diameter of 0.1", from 0.25" to 0.35" for example, represents a 21% increase in fill volume. In general, CAT6A F/UTP provides a minimum of 35% more fill capacity than CAT6A UTP. In addition, innovations in connector technology have made terminating CAT6A F/UTP actually easier than terminating bulkier CAT6A UTP.

Category 7 (CAT7) –Class F was published in 2002 by the ISO/IEC. It is not a TIA recognized standard and TIA plans to skip over it.

Category 7 specifies minimum performance standards for fully shielded cable (individually shielded pairs surrounded by an overall shield) transmitting data at rates up to 600 MHz. It comes with one of two connector styles: the standard RJ plug and a non-RJ-style plug and socket interface specified in IEC 61076-2-104:2.

Category 7a (CAT7a) –Class Fa (Amendment 1 and 2 to ISO/IEC 11801, 2nd Ed.) is a fully shielded cable that extends frequency from 600 MHz to 1000 MHz.

Category 8 – The TIA decided to skip Category 7 and 7A and go to Category 8. The TR-42.7 subcommittee is establishing specs for a 40-Gbps twisted-pair solution with a 2-GHz frequency. The proposed standard is for use in a two-point channel in a data center at 30 meters. It is expected to be ratified in February 2016. The TR-42.7 subcommittee is also incorporating ISO/IEC Class II cabling performance criteria into the standard. It is expected to be called TIA-568-C.2-1. The difference between Class I and Class II is that Class II allows for three different styles of connectors that are not compatible with one another or with the RJ-45 connector. Class I uses an RJ-45 connector and is backward compatible with components up to Category 6A. collapse


Black Box Explains...Type 1 vs. Type 6 Cable

Type 1 Cable is made of solid wire, typically 22 AWG bare copper. It has braided shielding around each pair. It’s recommended for long runs in walls, conduits, etc.

Type 6... more/see it nowCable is typically made of 26 AWG stranded copper and has one shield around both pairs. It’s lighter and more flexible than Type 1 Cable and has a better “look.” It’s recommended for use in office environments. collapse


Black Box Explains...Breakout-style cables.

With breakout- or fanout-style cables, the fibers are packaged individually. A breakout cable is basically several simplex cables bundled together in one jacket. Breakout cables are suitable for riser and... more/see it nowplenum applications, and conduit runs.

This differs from distribution-style cables where several tight-buffered fibers are bundled under the same jacket.

This design of the breakout cable adds strength to the cable, although that makes it larger and more expensive than distribution-style cables.

Because each fiber is individually reinforced, you can divide the cable into individual fiber lines. This enables quick connector termination, and eliminates the need for patch panels.

Breakout cable can also be more economical because it requires much less labor to terminate.

You may want to choose a cable that has more fibers than you actually need in case of breakage during termination or for future expansion. collapse


Black Box Explains…CAT6A UTP vs. F/UTP.

CAT6A is currently the cable of choice for future-proofing cabling installations and for 10-GbE networks.

There are two types of CAT6A cable, unshielded (UTP) and shielded (F/UTP). F/UTP denotes foiled/unshielded... more/see it nowtwisted pair and consists of four unshielded twisted pairs encased in an overall foil shield. This is not to be confused with an S/FTP (screened/foiled twisted pair) cable, which has four individually shielded twisted pairs encased in an overall braided shield.

CAT6A UTP
CAT6A UTP is constructed in a certain way to help eliminate crosstalk and ANEXT. (ANEXT is the measurement of the signal coupling between wire pairs in different and adjacent cables.) This includes larger conductors (23 AWG minimum), tighter twists, an extra internal airspace, an internal separator between the pairs, and a thicker outer jacket. These features also increase the outer diameter of the cable, typically to .35 inches in diameter, up from .25 inches for CAT6 cable. This increased diameter creates a greater distance between pairs in adjacent links, thus reducing the between-channel signal coupling. But CAT6A UTP cable is still affected by ANEXT.

According to the standards, ANEXT can be improved by laying CAT6A UTP cable loosely in pathways and raceways with space between the cables. This contrasts to the tightly bundled runs of CAT6/5e cable we are used to. The tight bundles present a worst-case scenario of six cables around one, thus the center cable would be adversely affected by ANEXT. Testing for ANEXT is a complex and time-consuming process where all possible wire-pair combinations are checked. It can take up to 50 minutes to test one link in a bundle of 24 CAT6A UTP cables.

CAT6A F/UTP
CAT6A F/UTP denotes foiled/unshielded twisted pairs and consists of four unshielded twisted pairs encased in an overall foil shield. ANEXT, and the time needed to test for it, can be greatly reduced, if not eliminated completely, by using CAT6A F/UTP. The foil shield acts as a barrier preventing external EMI/RFI from coupling onto the twisted pairs. It also prevents data signals from leaking out of the cable, making the cable more difficult to tap and better for secure installations. Studies also have shown that CAT6A F/UTP cable provides significantly more headroom (as much as 20 dB) than CAT6A UTP in 10-GbE over copper systems.

Bigger isn't always better.
CAT6A UTP cable has an overall allowable diameter of 0.354 inches. CAT6A F/UTP cable has an average outside diameter of 0.265–0.30 inches. That’s smaller than the smallest CAT6A UTP cable. An increase in the outside diameter (O.D.) of 0.1 inch, from 0.25 inches to 0.35 inches for example, represents a 21% increase in fill volume. In general, CAT6A F/UTP cable provides a minimum of 35% more fill capacity that CAT6A UTP cable.

Also because of its large diameter, CAT6A UTP requires a larger bend radius, more pathways, less dense patch panel connections, and extensive ANEXT testing.

CAT6A F/UTP cable is actually easier to handle, requires less bend radius, and uses smaller pathways. In addition, innovations in connector technology has made terminating CAT6A F/UTP cable simpler. In terms of grounding, the requirements for both UTP and F/UTP cable fall under TIA/EIA J-STD-607-A Commercial Building Grounding (Earthing) and Bonding Requirements for Telecommunications.

The advantages of CAT6A F/UTP vs. UTP
In summary, there are a number of advantages of using CAT6A F/UTP over CAT6A UTP in 10-GbE networks.

1. Shielding eliminates ANEXT and EMI/RFI problems and testing.
2. Data line security is enhanced because of shielding.
3. Lighter, slimmer cable provides higher port density.
4. Smaller outside diameter cable is easier to handle and reduces installation costs.
5. Shielded cable uses less space in conduits.

For more information, see the CAT6A F/UTP vs. UTP: What You Need to Know white paper in the Resources section at blackbox.com. collapse


Black Box Explains...SCSI Ultra2 and LVD (Low-Voltage Differential).

Small Computer Systems Interface (SCSI), pronounced “scuzzy,” has been the dominant technology used to connect computers and high-speed peripherals since the 1980s. SCSI technology is constantly evolving to accommodate increased... more/see it nowbandwidth needs. One of the more recent developments is Ultra2 SCSI.

Because Ultra2 SCSI is backward compatible, it works with all legacy equipment. Ultra2 doubles the possible bandwidth on the bus from 40 to 80 MBps! Just as importantly, Ultra2 supports distances up to 12 meters (39.3 ft.) for a multiple-device configuration. Ultra2 uses Low-voltage Differential (LVD) techniques to transfer data at faster rates with fewer errors. Don’t confuse Ultra2 with LVD. Ultra2 is a data-transfer method; LVD is the signaling technique used to transfer the data.

Cables are very important when designing or upgrading a system to take advantage of Ultra2 SCSI. Cables and connectors must be of high quality and they should come from a reputable manufacturer to prevent crosstalk and minimize signal radiation. BLACK BOX® Ultra2 LVD cables are constructed of the finest-quality components to provide your system with the maximum protection and highest possible data-transfer rates. collapse


Black Box Explains...USB.

The Universal Serial Bus (USB) hardware (plug-and-play) standard makes connecting peripherals to your computer easy. USB 1.1, introduced in 1995, is the original USB standard. It has two data rates:... more/see it now12 Mbps and 1.5 Mbps. USB 2.0, or Hi-Speed USB 2.0, was released in 2000. It increased the peripheral-to-PC speed from 12 Mbps to 480 Mbps, or 40 times faster than USB 1.1. This increase in bandwidth enabled the use of peripherals requiring higher throughput, such as CD/DVD burners, scanners, digital cameras, and video equipment. It is backward-compatible with USB 1.1.

The newest USB standard, USB 3.0 (or SuperSpeed USB), (2008) provides vast improvements over USB 2.0. It promises speeds up to 4.8 Gbps, nearly ten times that of USB 2.0. USB 3.0 has the flat USB Type A plug, but inside there is an extra set of connectors and the edge of the plug is blue instead of white. The Type B plug looks different with an extra set of connectors.

USB 3.0 adds a physical bus running in parallel with the existing 2.0 bus. USB 3.0 cable contains nine wires, four wire pairs plus a ground. It has two more data pairs than USB 2.0, which has one pair for data and one pair for power. The extra pairs enable USB 3.0 to support bidirectional async, full-duplex data transfer instead of USB 2.0’s half-duplex polling method.

USB 3.0 provides 50% more power than USB 2.0 (150 mA vs 100 mA) to unconfigured devices and up to 80% more power (900 mA vs 500 mA) to configured devices. Also, USB 3.0 conserves more power when compared to USB 2.0, which uses power when the cable isn’t being used. collapse


Black Box Explains... Speaker wire gauge.

Wire gauge (often shown as AWG, for American Wire Gauge) is a measure of the thickness of the wire. The more a wire is drawn or sized, the smaller its... more/see it nowdiameter will be. The lower the wire gauge, the thicker the wire.

For example, a 24 AWG wire is thinner than a 14 AWG wire. A lower AWG means longer transmission distance and better integrity. As a rule of thumb, power loss decreases as the wire size increases.

When it comes to choosing speaker cable, consider a few factors: distance, the type of system and amplifier you have, the frequencies of the signals being handled, and any specifications that the speaker manufacturer recommends.

For most home applications where you simply need to run cable from your stereo to speakers in the same room—or even behind the walls to other rooms—16 AWG cable is usually fine.

If you’re considering runs of more than 40 feet (12.1 m), consider using 14 AWG or even 12 AWG cable. They both offer better transmission and less resistance over longer distances. You should probably choose 12 AWG cable for high-end audio systems with higher power output or for low-frequency subwoofers. As a rule of thumb, power loss decreases as the wire size increases.

To terminate your cable, choose gold connectors. Because gold resists oxidation over time, gold connectors wear better and offer better peformance than other connectors do. collapse

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