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Black Box Explains...Shielded vs. unshielded cable.

The environment determines whether cable should be shielded or unshielded.

Shielding is the sheath surrounding and protecting the cable wires from electromagnetic leakage and interference. Sources of this electromagnetic activity... more/see it now(EMI)—commonly referred to as noise—include elevator motors, fluorescent lights, generators, air conditioners, and photocopiers. To protect data in areas with high EMI, choose a shielded cable.

Foil is the most basic cable shield, but a copper-braid shield provides more protection. Shielding also protects cables from rodent damage. Use a foil-shielded cable in busy office or retail environments. For industrial environments, you might want to choose a copper-braid shield.

For quiet office environments, choose unshielded cable. collapse


Black Box Explains...SCSI-1, SCSI-2, SCSI-3, and SCSI-5.

There are standards…and there are standards applied in real-world applications. This Black Box Explains illustrates how SCSI is interpreted by many SCSI manufacturers. Think of these as common SCSI connector... more/see it nowtypes, not as firm SCSI specifications. Notice, for instance, there’s a SCSI-5, which isn’t listed among the other approved and proposed specifications. However, for advanced SCSI multiport applications, SCSI-5 is often the connector of choice.

SCSI-1
Supports transfer rates up to 5 MBps and seven SCSI devices on an 8-bit bus. The most common connector is the Centronics® 50 or a DB50. A Micro Ribbon 50 is also used for internal connections. SCSI-1 equipment, such as controllers, can also have Burndy 60 or 68 connectors.

SCSI-2
SCSI-2 introduced optional 16- and 32-bit buses called “Wide SCSI.“ Transfer rate is normally 10 MBps but SCSI-2 can go up to 40 MBps with Wide and Fast SCSI. SCSI-2 usually features a Micro D 50-pin connector with thumbclips. It’s also known as Mini 50 or Micro DB50. A Micro Ribbon 60 connector may also be used for internal connections.

SCSI-3
Found in many high-end systems, SCSI-3 commonly uses a Micro D 68-pin connector with thumbscrews. It’s also known as Mini 68. The most common bus width is 16 bits with transfer rates of 20 MBps.

SCSI-5
SCSI-5 is also called a Very High-Density Connector Interface (VHDCI) or 0.8-mm connector. It’s similar to the SCSI-3 MD68 connector in that it has 68 pins, but it has a much smaller footprint. SCSI-5 is designed for SCSI-5, next-generation SCSI connections. Manufacturers are integrating this 0.8-mm design into controller cards. It’s also the connector of choice for advanced SCSI multiport applications. Up to four channels can be accommodated in one card slot. Connections are easier where space is limited. collapse


Black Box Explains... SCSI termination

Passive termination
This is the oldest method of termination. A passive terminator sits on the bus to minimize reflections at the end of the cable. Passive terminators simply provide impedance close... more/see it nowto that of the cable. The terminator is “passive” because it doesn’t do any work to regulate power for termination; it relies on the interface card to provide steady power.

Active termination
This is a more stable form of terminating SCSI cables. Active terminators control the impedance at the end of the SCSI bus by using a voltage regulator, not just the power supplied by the interface card.

Forced-perfect termination
Of all SCSI terminators, this is the most complex. A cable with a forced-perfect terminator can actually change its impedance to compensate for variations along the bus. Forced-perfect terminators force the impedance of the cable to match each device through diode switching and biasing. collapse


Fiber optic cable construction and types.

Multimode vs. single-mode
Multimode cable has a large-diameter core and multiple pathways of light. It is most commonly available in two core sizes: 50-micron and 62.5-micron.

Multimode fiber optic cable can... more/see it nowbe used for most general data and voice fiber applications such as adding segments to an existing network, and in smaller applications such as alarm systems and bringing fiber to the desktop. Both multimode cable cores use either LED or laser light sources.

Multimode 50-micron cable is recommended for premise applications?(backbone, horizontal, and intrabuilding connections). It should be considered for any new construction and for installations because it provides longer link lengths and/or higher speeds, particularly in the 850-nm wavelength, than 62.5-micron cable does.

Multimode cable commonly has an orange or aqua jacket; single-mode has yellow. Other colors are available for various applications and for identification purposes.

Single-mode cable has a small (8–10-micron) glass core and only one pathway of light. With only a single wavelength of light passing through its core, single-mode cable realigns the light toward the center of the core instead of simply bouncing it off the edge of the core as multimode does.

Single-mode cable provides 50 times more distance than multimode cable does. Consequently, single-mode cable is typically used in high-bandwidth applications and in long-haul network connections spread out over extended areas, including cable television and campus backbone applications. Telcos use it for connections between switching offices. Single-mode cable also provides higher bandwidth, so you can use a pair of single-mode fiber strands full-duplex at more than twice the throughput of multimode fiber.

Construction
Fiber optic cable consists of a core, cladding, coating, buffer strengthening fibers, and cable jacket.

The core is the physical medium that transports optical data signals from an attached light source to a receiving device. It is a single continuous strand of glass or plastic that’s measured (in microns) by the size of its outer diameter.

All fiber optic cable is sized according to its core’s outer diameter. The two multimode sizes most commonly available are 50 and 62.5 microns. Single-mode cores are generally less than 9 microns.

The cladding is a thin layer that surrounds the fiber core and serves as a boundary that contains the light waves and causes the refraction, enabling data to travel throughout the length of the fiber segment.

The coating is a layer of plastic that surrounds the core and cladding to reinforce the fiber core, help absorb shocks, and provide extra protection against excessive cable bends. These coatings are measured in microns (µ); the coating is 250µ and the buffer is 900µ.

Strengthening fibers help protect the core against crushing forces and excessive tension during installation. This material is generally Kevlar® yarn strands within the cable jacket.

The cable jacket is the outer layer of any cable. Most fiber optic cables have an orange jacket, although some types can have black, yellow, aqua or other color jackets. Various colors can be used to designate different applications within a network.

Simplex vs. duplex patch cables
Multimode and single-mode patch cables can be simplex or duplex.

Simplex has one fiber, while duplex zipcord has two fibers joined with a thin web. Simplex (also known as single strand) and duplex zipcord cables are tight-buffered and jacketed, with Kevlar strength members.

Because simplex fiber optic cable consists of only one fiber link, you should use it for applications that only require one-way data transfer. For instance, an interstate trucking scale that sends the weight of the truck to a monitoring station or an oil line monitor that sends data about oil flow to a central location.

Use duplex multimode or single-mode fiber optic cable for applications that require simultaneous, bidirectional data transfer. Workstations, fiber switches and servers, Ethernet switches, backbone ports, and similar hardware require duplex cable.

PVC (riser) vs. plenum-rated
PVC cable (also called riser-rated cable even though not all PVC cable is riser-rated) features an outer polyvinyl chloride jacket that gives off toxic fumes when it burns. It can be used for horizontal and vertical runs, but only if the building features a contained ventilation system. Plenum can replace PVC, but PVC cannot be used in plenum spaces.

“Riser-rated” means that the jacket is fire-resistant. However, it can still give off noxious fumes when overheated. The cable carries an OFNR rating and is not for use in plenums.

Plenum-jacketed cables have FEP, such as Teflon®, which emits less toxic fumes when it burns. A plenum is a space within the building designed for the movement of environmental air. In most office buildings, the space above the ceiling is used for the HVAC air return. If cable goes through that space, it must be “plenum-rated.”

Distribution-style vs. breakout-style
Distribution-style cables have several tight-buffered fibers bundled under the same jacket with Kevlar or fiberglass rod reinforcement. These cables are small in size and are typically used within a building for short, dry conduit runs, in either riser or plenum applications. The fibers can be directly terminated, but because the fibers are not individually reinforced, these cables need to be terminated inside a patch panel, junction box, fiber enclosure, or cabinet.

Breakout-style cables are made of several simplex cables bundled together, making a strong design that is larger than distribution cables. Breakout cables are suitable for riser and plenum applications.

Loose-tube vs. tight-buffered
Both loose-tube and tight-buffered cables contain some type of strengthening member, such as aramid yarn, stainless steel wire strands, or even gel-filled sleeves. But each is designed for very different environments.

Loose-tube cable is specifically designed for harsh outdoor environments. It protects the fiber core, cladding, and coating by enclosing everything within semi-rigid protective sleeves or tubes. Many loose-tube cables also have a water-resistant gel that surrounds the fibers. This gel helps protect them from moisture, so the cables are great for harsh, high-humidity environments where water or condensation can be a problem. The gel-filled tubes can also expand and contract with temperature changes. Gel-filled loose-tube cable is not the best choice for indoor applications.

Tight-buffered cable, in contrast, is optimized for indoor applications. Because it’s sturdier than loose-tube cable, it’s best suited for moderate-length LAN/WAN connections, or long indoor runs. It’s easier to install as well, because there’s no messy gel to clean up and it doesn’t require a fan-out kit for splicing or termination.

Indoor/outdoor cable
Indoor/outdoor cable uses dry-block technology to seal ruptures against moisture seepage and gel-filled buffer tubes to halt moisture migration. Comprised of a ripcord, core binder, a flame-retardant layer, overcoat, aramid yarn, and an outer jacket, it is designed for aerial, duct, tray, and riser applications.

Interlocking armored cable
This fiber cable is jacketed in aluminum interlocking armor so it can be run just about anywhere in a building. Ideal for harsh environments, it is rugged and rodent resistant. No conduit is needed, so it’s a labor- and money-saving alternative to using innerducts for fiber cable runs.

Outside-plant cable is used in direct burials. It delivers optimum performance in extreme conditions and is terminated within 50 feet of a building entrance. It blocks water and is rodent-resistant.

Interlocking armored cable is lightweight and flexible but also extraordinarily strong. It is ideal for out-of-the-way premise links.

Laser-optimized 10-Gigabit cable
Laser-optimized multimode fiber cable assemblies differ from standard multimode cable assemblies because they have graded refractive index profile fiber optic cable in each assembly. This means that the refractive index of the core glass decreases toward the outer cladding, so the paths of light towards the outer edge of the fiber travel quicker than the other paths. This increase in speed equalizes the travel time for both short and long light paths, ensuring accurate information transmission and receipt over much greater distances, up to 300 meters at 10 Gbps.

Laser-optimized multimode fiber cable is ideal for premise networking applications that include long distances. It is usually aqua colored.

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DisplayPort cable.

DisplayPort is a digital video interface that was designed by the Video Electronics Standards Association (VESA) in 2006 and has been produced since 2008. It’s incredibly versatile, with the capability... more/see it nowto deliver digital video, audio, bidirectional communications, and accessory power over a single connector.

DisplayPort cables are targeted at the computer world rather than at consumer electronics. DisplayPort is used to connect digital audio/video computers, displays, monitors, projectors, HDTVs, splitters, extenders, and other devices that support resolutions up to 4K and beyond. Unlike HDMI, however, DisplayPort is an open standard with no royalties.

With the proper adapters, DisplayPort cable can carry DVI and HDMI signals, although this doesn’t work the other way around—DVI and HDMI cable can’t carry DisplayPort. Because DisplayPort can provide power to attached devices, DisplayPort to HDMI or DVI adapters don’t need a separate power supply.

DisplayPort supports cable lengths of up to 15 meters with maximum resolutions at cable lengths up to 3 meters. Bidirectional signaling enables DisplayPort to both send and receive data from an attached device.

DisplayPort v1.1: 10.8 Gbps over a 2-meter cable.

DisplayPort v1.2: 21.6 Gbps (4K). DisplayPort v1.2 also enables you to daisychain up to four monitors with only a single output cable. It also offers the future promise of DisplayPort Hubs that would operate much like a USB hub.

DisplayPort v1.3: 2.4 Gbps. (5K)

The standard DisplayPort connector is very compact and features latches that don’t add to the connector’s size. Unlike HDMI, a DisplayPort connector is easily lockable with a pinch-down locking hood, so it can't be easily dislodged. However, a quick squeeze of the connector releases the latch.

The Mini DisplayPort (MiniDP or mDP) is a miniatured version of the DisplayPort interface. It carries both digital and analog computer video and audio signals. Apple® introduced the Mini DisplayPort connector in 2008 and it is now on all new Mac® computers. It is also being used in newer PC notebooks. This small form factor connector fully supports the VESA DisplayPort protocol. It is particularly useful on systems where space is at a premium, such as laptops, or to support multiple connectors on reduced height add-in cards.

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Black Box Explains...Cable management.

Corporate networks are complex systems of PCs, servers, printers, and the devices that connect them. Getting everything to work in harmony requires bundles of cables, and managing all those cables... more/see it nowfrom inside a telecommunications closet can be a daunting task. To connect cable bundles to rackmounted equipment (like patch panels, hubs, switches, or routers), you need to direct the bundles overhead, vertically, and horizontally.

A popular choice for overhead cable routing is a ladder rack. Ladder racks come in many varieties. They can run along a wall supported by brackets or they can be installed overhead and supported by a threaded rod. Ladder racks can support large cable bundles neatly and safely. Because bundles lie flat on a ladder rack, cables aren’t subjected to harsh bends. You can run ladder racks directly to the top of most standard telecommunications racks that conform to TIA/EIA standards.

Use vertical cable managers to route cable bundles along the sides of a rack. These “cable troughs” as they’re sometimes called can be single sided—or double sided to route cable bundles to the rear of equipment and to the ports on the front as well. Vertical cable managers usually come with some type of protection for the cable, such as grommeted holes to protect the cable jacket or a cover that may clip on or act as a door.

Horizontal cable managers are usually a series of rings that directs cables in an orderly fashion toward the ports of hubs, switches, and patch panels. collapse


Black Box Explains… Category 7/Class F.


Category 7/Class F (ISO/IEC 11801:2002) specifies a frequency range of 1–600 MHz over 100 meters of fully shielded twisted-pair cabling. It encompasses four individually shielded pairs inside an overall shield,... more/see it nowcalled Shielded/Foiled Twisted Pair (S/FTP) or Foiled/ Foiled Twisted Pair (F/FTP). There is a pending class Fa, based on the use of S/FTP cable to 1000 MHz. It can support 10GBASE-T transmissions.

With both types of cable, each twisted pair is enclosed in foil. In S/FTP cable, all four pairs are encased in an overall metal braid. In F/FTP, the four pairs are encased in foil.

Category 7/Class F cable can be terminated with two interface designs as specified in IEC 6063-7-7 and IEC 61076-3-104. One is an RJ-45 compatible GG-45 connector. The other is the more common TERA connector, which was launched in 1999.

Category 7/Class F is backwards compatible with traditional CAT6 and CAT5 cable, but it has far more stringent specifications for crosstalk and system noise. The fully shielded cable virtually eliminates crosstalk between the pairs. In addition, the cable is noise resistant, which makes the Category 7/Class F systems ideal for high EMI areas, such as industrial and medical imaging facilities.
Category 7/Class F cable can also increase security by preventing the emission of data signals from the cable to nearby areas. collapse


Black Box Explains...The MPO connector.

MPO stands for multifiber push-on connector. It is a connector for multifiber ribbon cable that generally contains 6, 8, 12, or 24 fibers. It is defined by IEC-61754-7 and TIA-604-5-D,... more/see it nowalso known as FOCIS 5. The MPO connector, combined with lightweight ribbon cable, represents a huge technological advance over traditional multifiber cables. It’s lighter, more compact, easier to install, and less expensive.

A single MPO connector replaces up to 12, 24, or 36 standard connectors. This very high density means lower space requirements and reduced costs for your installation. Traditional, tight-buffered multifiber cable needs to have each fiber individually terminated by a skilled technician. But MPO fiber optic cable, which carries multiple fibers, comes preterminated. Just plug it in and you’re ready to go.

MPO connectors feature an intuitive push-pull latching sleeve mechanism with an audible click upon connection and are easy to use. The MPO connector is similar to the MT-RJ connector. The MPO’s ferrule surface of 2.45 x 6.40 mm is slightly bigger than the MT-RJ’s, and the latching mechanism works with a sliding sleeve latch rather than a push-in latch.

The MPO connector can be either male or female. You can tell the male connector by the two alignment pins protruding from the end of the ferrule. The MPO ferrule is generally flat for multimode applications and angled for single-mode applications.

MPO connectors are also commonly called MTP® connectors, which is a registered trademark of US Conec. The MTP connector is an MPO connector engineered with particular enhancements to improve optical and mechanical performance. The two connectors are compatible. 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...USB.

What is USB?
Universal Serial Bus (USB) is a royalty-free bus specification developed in the 1990s by leading manufacturers in the PC and telephony industries to support plug-and-play peripheral connections. USB... more/see it nowhas standardized how peripherals, such as keyboards, disk drivers, cameras, printers, and hubs) are connected to computers.

USB offers increased bandwidth, isochronous and asynchronous data transfer, and lower cost than older input/output ports. Designed to consolidate the cable clutter associated with multiple peripherals and ports, USB supports all types of computer- and telephone-related devices.

Universal Serial Bus (USB) USB detects and configures the new devices instantly.
Before USB, adding peripherals required skill. You had to open your computer to install a card, set DIP switches, and make IRQ settings. Now you can connect digital printers, recorders, backup drives, and other devices in seconds. USB detects and configures the new devices instantly.

Benefits of USB.
• USB is “universal.” Almost every device today has a USB port of some type.
• Convenient plug-and-play connections. No powering down. No rebooting.
• Power. USB supplies power so you don’t have to worry about adding power. The A socket supplies the power.
• Speed. USB is fast and getting faster. The original USB 1.0 had a data rate of 1.5 Mbps. USB 3.0 has a data rate of 4.8 Gbps.

USB Standards

USB 1.1
USB 1.1, introduced in 1995, is the original USB standard. It has two data rates: 12 Mbps (Full-Speed) for devices such as disk drives that need high-speed throughput and 1.5 Mbps (Low-Speed) for devices such as joysticks that need much lower bandwidth.

USB 2.0
In 2002, USB 2.0, (High-Speed) was introduced. This version is backward-compatible with USB 1.1. It increases the speed of the peripheral to PC connection from 12 Mbps to 480 Mbps, or 40 times faster than USB 1.1.

This increase in bandwidth enhances the use of external peripherals that require high throughput, such as printers, cameras, video equipment, and more. USB 2.0 supports demanding applications, such as Web publishing, in which multiple high-speed devices run simultaneously.

USB 3.0
USB 3.0 (SuperSpeed) (2008) provides vast improvements over USB 2.0. USB 3.0 has speeds up to 5 Gbps, nearly ten times that of USB 2.0. USB 3.0 adds a physical bus running in parallel with the existing 2.0 bus.

USB 3.0 is designed to be backward compatible with USB 2.0.

USB 3.0 Connector
USB 3.0 has a 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. Type A plugs from USB 3.0 and 2.0 are designed to interoperate. USB 3.0 Type B plugs are larger than USB 2.0 plugs. USB 2.0 Type B plugs can be inserted into USB 3.0 receptacles, but the opposite is not possible.

USB 3.0 Cable
The 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 asynchronous, full-duplex data transfer instead of USB 2.0’s half-duplex polling method.

USB 3.0 Power
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. It also conserves power too compared to USB 2.0, which uses power when the cable isn’t being used.

USB 3.1
Released in 2013, is called SuperSpeed USB 10 Gbps. There are three main differentiators to USB 3.1. It doubles the data rate from 5 Gbps to 10 Gbps. It will use the new, under-development Type C connector, which is far smaller and designed for use with everything from laptops to mobile phones. The Type C connector is being touted as a single-cable solution for audio, video, data, and power. It will also have a reversible plug orientation. Lastly, will have bidirectional power delivery of up to 100 watts and power auto-negotiation. It is backward compatible with USB 3.0 and 2.0, but an adapter is needed for the physical connection.

Transmission Rates
USB 3.0: 4.8 Gbps
USB 2.0: 480 Mbps
USB 1.1: 12 Mbps

Cable Length/Node
5 meters (3 meters for 3.0 devices requiring higher speeds).
Devices/bus: 127
Tier/bus: 5
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