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Black Box Explains...How fiber is insulated for use in harsh environments.

Fiber optic cable not only gives you immunity to interference and greater signal security, but it’s also constructed to insulate the fiber’s core from the stress associated with use in... more/see it nowharsh environments.

The core is a very delicate channel that’s used to transport data signals from an optical transmitter to an optical receiver. To help reinforce the core, absorb shock, and provide extra protection against cable bends, fiber cable contains a coating of acrylate plastic.

In an environment free from the stress of external forces such as temperature, bends, and splices, fiber optic cable can transmit light pulses with minimal attenuation. And although there will always be some attenuation from external forces and other conditions, there are two methods of cable construction to help isolate the core: loose-tube and tight-buffer construction.

In a loose-tube construction, the fiber core literally floats within a plastic gel-filled sleeve. Surrounded by this protective layer, the core is insulated from temperature extremes, as well as from damaging external forces such as cutting and crushing.

In a tight-core construction, the plastic extrusion method is used to apply a protective coating directly over the fiber coating. This helps the cable withstand even greater crushing forces. But while the tight-buffer design offers greater protection from core breakage, it’s more susceptible to stress from temperature variations. Conversely, while it’s more flexible than loose-tube cable, the tight-buffer design offers less protection from sharp bends or twists. collapse


Black Box Explains...Connectors.



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Black Box Explains...RS-232.

RS-232, also known as RS-232C and TIA/EIA-232-E, is a group of electrical, functional, and mechanical specifications for serial interfaces between computers, terminals, and peripherals. The RS-232 standard was developed by... more/see it nowthe Electrical Industries Association (EIA), and defines requirements for connecting data communications equipment (DCE)—modems, converters, etc.—and data terminal equipment (DTE)—computers, controllers, etc.) devices. RS-232 transmits data at speeds up to 115 Kbps and over distances up to 50 feet (15.2 m).

The standard, which is functionally equivalent to ITU V.24/V.28, specifies the workings of the interface, circuitry, and connector pinning. Both sync and async binary data transmission fall under RS-232. Although RS-232 is sometimes still used to transmit data from PCs to peripheral devices, the most common uses today are for network console ports and for industrial devices.

Even though RS-232 is a “standard,” you can’t necessarily expect seamless communication between two RS-232 devices. Why? Because different devices have different circuitry or pinning, and different wires may be designated to perform different functions.

The typical RS-232 connector is DB25, but some PCs and other data communication devices have DB9 connectors and many newer devices have RJ-45 RS-232 ports. To connect 9-pin PC ports or RJ-45 to devices with 25-pin connectors, you will require a simple adapter cable. 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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Black Box Explains...Category 6.

Category 6 (CAT6)–Class E has a specified frequency of 250 MHz, significantly improved bandwidth capacity over CAT5e, and easily handles Gigabit Ethernet transmissions. In recent years, it has been the... more/see it nowcable of choice for new structured cabling systems. CAT6 supports 1000BASE-T and, depending on the installation, 10GBASE-T (10-GbE).

10-GbE over CAT6 introduces the problem of 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, TSB-155 qualifies 10-GbE over CAT6 up to 55 meters and requires it to be 100% tested. To mitigate ANEXT in CAT6, it is recommended that you unbundle the cables and increase the separation between the cables.

You can always contact Black Box Tech Support to answer your cabling questions. Our techs can recommend cable testers and steer you in the right direction when you’re installing new cabling. And the advice is FREE! collapse


Black Box Explains...What to look for in a channel solution.


Channel solution. You hear the term a lot these days to describe complete copper or fiber cabling systems. But what exactly is a channel solution and what are its benefits?... more/see it now

A definition.
A channel solution is a cabling system from the data center to the desktop where every cable, jack, and patch panel is designed to work together and give you consistent end-to-end performance when compared with the EIA/TIA requirements.

Its benefits.
A channel solution is beneficial because you have some assurance that your cabling components will perform as specified. Without that assurance, one part may not be doing its job, so your entire system may not be performing up to standard, which is a problem — especially if you rely on bandwidth-heavy links for video and voice.

What to look for.
There are a lot of channel solutions advertised on the Internet and elsewhere. So what exactly should you be looking for?

For one, make sure it’s a fully tested, guaranteed channel solution. The facts show an inferior cabling system can cause up to 70 percent of network downtime — even though it usually represents only 5 percent of an initial network investment. So don’t risk widespread failure by skimping on a system that doesn’t offer guaranteed channel performance. You need to make sure the products are engineered to meet or go beyond the key measurements for CAT5e or CAT6 performance.

And, sure, they may be designed to work together, but does the supplier absolutely guarantee how well they perform as part of a channel — end to end? Don’t just rely on what the supplier says. They may claim their products meet CAT5e or CAT6 requirements, but the proof is in the performance. Start by asking if the channel solution is independently tested and certified by a reputable third party. There are a lot of suppliers out there who don’t have the trademarked ETL approval logo, for example.

What ETL Verified means.
The ETL logo certifies that a channel solution has been found to be in compliance with recognized standards. To ensure consistent top quality, Black Box participates in independent third-party testing by InterTek Testing Services/ETL Semko, Inc. Once a quarter, an Intertek inspector visits Black Box and randomly selects cable and cabling products for testing.

The GigaTrue® CAT6 and GigaBase® CAT5e Solid Bulk Cable are ETL Verified at the component level to verify that they conform to the applicable industry standards. The GigaTrue® CAT6 and GigaBase® CAT5e Channels, consisting of bulk cable, patch cable, jacks, patch panels, and wiring blocks, are tested and verified according to industry standards in a LAN environment under InterTek’s Cabling System Channel Verification Program. For the latest test results, contact our FREE Tech Support. collapse

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