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Black Box Explains... Fan-out kits.

Furcating is the process of adding protective tubing to each fiber within a loose-tube cable. It can be a headache-inducing task if you don’t have the right tools. If you... more/see it nowbend the cable or buffer tubes past their recommended bend radius, or if you allow them to kink, you’ll end up with substandard cable connections and splices that can break down over time. And, if the cable is outdoors, it can become exposed to the elements. The end result: a damaged cable without optimal transmission performance.

That’s why a fan-out kit is an absolute must during furcation. These kits enable you to branch out the fragile fiber strands from a buffer tube into protective tubing so you can add a connector. And, you can do it without using splicing hardware, trays, and pigtails.

To separate the fibers, use the kit’s fan-out assembly, which is color-coded to match the fiber color scheme. The assembly protects the cable’s bend radius. It also eliminates excessive strain on the fibers by isolating them from tensile forces.

Several types of fan-out kits are available for both indoor and outdoor cross-connects. The outdoor kits include components that compensate for wider temperature fluctuations. Some kits are used to terminate loose-tube cables with 6 or 12 fibers per buffer tube. Others enable you to furcate and terminate more than 200 loose-tube cable fibers, sealing the cable sheath and providing a moisture barrier at the point of termination. These kits require no additional hardware.

Although it’s recommended that you terminate loose-tube cable at a patch panel, that might not always be possible. For this, there are “spider“ type fan-out kits, which affix a stronger tubing to the bare fiber. The tubing is typically multilayered, consisting of a FEP inner tube that holds the individual fiber, an aramid yarn strength member, and an outer protective PVC jacket. Once you strip back the cable jacket, you thread the fibers into the fan-out inserts. collapse


Black Box Explains... Guidelines for choosing fiber optic cable.


Fiber optic cable is becoming one of the fastest-growing transmission mediums for both new cabling installations and upgrades, including backbone, horizontal, and even desktop applications. It’s favored for applications that... more/see it nowneed high bandwidth, long distances, and complete immunity to electrical interference.

It’s ideal for high-data-rate systems such as Gigabit Ethernet, FDDI, multimedia, ATM, SONET, Fibre Channel, or any other network that requires the transfer of large, bandwidth-consuming data files, particularly over long distances.

Fiber offers the following advantages:

Greater bandwidth—Because fiber provides far greater bandwidth than copper and has proven performance at rates up to 10 Gbps, it gives network designers future-proofing capabilities as network speeds and requirements increase.

Also, fiber optic cable can carry more information with greater fidelity than copper wire. That’s why the telephone networks use fiber and many CATV companies are converting to fiber.

Low attenuation and greater distance—Because the fiber optic signal is made of light, very little signal loss occurs during transmission, and data can move at higher speeds and greater distances. Fiber does not have the 100-meter (328-ft.) distance limitation of unshielded twisted-pair copper (without a booster). Fiber distances can range from 300 meters (984.2 ft.) to 40 kilometers (24.8 mi.), depending on the style of cable, wavelength, and network. (Fiber distances are typically measured in metric units.) Because fiber signals need less boosting than copper ones do, the cable performs better.

Security—Your data is safe with fiber cable. It doesn’t radiate signals and is extremely difficult to tap. If the cable is tapped, it’s very easy to monitor because the cable leaks light, causing the entire system to fail. If an attempt is made to break the physical security of your fiber system, you’ll know it.

Fiber networks also enable you to put all your electronics and hardware in one central location, instead of having wiring closets with equipment throughout the building.

Immunity and reliability—Fiber provides extremely reliable data transmission. It’s completely immune to many environmental factors that affect copper cable. The core is made of glass, which is an insulator, so no electric current can flow through. It’s immune to electromagnetic interference and radio-frequency interference (EMI/RFI), crosstalk, impedance problems, and more. You can run fiber cable next to industrial equipment without worry. Fiber is also less susceptible to temperature fluctuations than copper and can be submerged in water.

Design—Fiber is lightweight, thin, and more durable than copper cable. Plus, fiber optic cable has pulling specifications that are up to 10 times greater than copper cable’s. Its small size makes it easier to handle, and it takes up much less space in cabling ducts. Although fiber is still more difficult to terminate than copper, advancements in connectors are making termination easier. In addition, fiber is actually easier to test than copper cable.

Migration—The proliferation and lower costs of media converters are making copper to fiber migration much easier. The converters provide seamless links and enable the use of existing hardware. Fiber can be incorporated into networks in planned upgrades.

Standards—TIA/EIA standards are bringing fiber closer to the desktop. TIA/EIA-785, ratified in 2001, provides a cost-effective migration path from 10-Mbps Ethernet to 100-Mbps Fast Ethernet over fiber (100BASE-SX). An addendum to the standard eliminates limitations in transceiver designs. In addition, in June 2002, the IEEE approved a 10-Gigabit Ethernet (10-GbE) standard.

Costs—The cost for fiber cable, components, and hardware is steadily decreasing. Installation costs for fiber are higher than copper because of the skill needed for terminations. Overall, fiber is more expensive than copper in the short run, but it may actually be less expensive in the long run. Fiber typically costs less to maintain, has much less downtime, and requires less networking hardware. And fiber eliminates the need to recable for higher network performance.

Types of fiber cable and standards.

Multimode, 50- and 62.5-micron cable—Multimode cable has a large-diameter core and multiple pathways of light. It comes in two core sizes: 50-micron and 62.5-micron.

Multimode fiber optic cable can be used for most general data and voice fiber applications, such as bringing fiber to the desktop, adding segments to an existing network, and in smaller applications such as alarm systems. Both 50- and 62.5-micron cable feature the same cladding diameter of 125 microns, but 50-micron fiber cable features a smaller core (the light-carrying portion of the fiber).

Although both can be used in the same way, 50-micron cable is recommended for premise applications (backbone, horizontal, and intrabuilding connections) and should be considered for any new construction and installations. Both also use either LED or laser light sources. The big difference between the two is that 50-micron cable provides longer link lengths and/or higher speeds, particularly in the 850-nm wavelength.

Single-mode, 8–10-micron cable—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. Consequently, single-mode cable is typically used 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 for up to twice the throughput of multimode fiber. collapse


Black Box Explains...DIN rail usage.

DIN rail is an industry-standard metal rail, usually installed inside an electrical enclosure, which serves as a mount for small electrical devices specially designed for use with DIN rails. These... more/see it nowdevices snap right onto the rails, sometimes requiring a set screw, and are then wired together.

Many different devices are available for mounting on DIN rails: terminal blocks, interface converters, media converter switches, repeaters, surge protectors, PLCs, fuses, or power supplies, just to name a few.

DIN rails are a space-saving way to accommodate components. And because DIN rail devices are so easy to install, replace, maintain, and inspect, this is an exceptionally convenient system that has become very popular in recent years.

A standard DIN rail is 35 mm wide with raised-lip edges, its dimensions outlined by the Deutsche Institut für Normung, a German standardization body. Rails are generally available in aluminum or steel and may be cut for installation. Depending on the requirements of the mounted components, the rail may need to be grounded. collapse


Black Box Explains...KVM tray technology.

KVM tray technology. What we do that others don’t.
From the solid construction of our KVM trays, to unique features like LEDs on the ?front panel and integrated KVM switching, Black Box’s... more/see it nowKVM trays are miles ahead of the competition.

Nothing reduces clutter in a server room like KVM trays that are 1- or 2U high, and ?mount in a cabinet or rack. Here are some of the features that set our KVM trays apart.

TFT LCD support.
This type of monitor uses thin-film transistor (TFT) technology to improve image quality, resulting in higher resolutions, better image contrast, and addressability. All our KVM trays support TFT LCD panel monitors.

Viewing angles.
The screens on our KVM trays are viewable from nearly any angle. Because of the size of our screens, from 15" to 19", viewing angles vary from 140° x 120° all the way up to 160° x 160°, so you don’t always have to be standing directly in front of the monitor to see what’s happening on it.

Universal rail.
Our ServTray Complete family of KVM trays (KVT417A-R2, etc.) has adjustable length instead of a variety of rear bracket sites. This universal rail rear bracket size fits racks with depths of 23.7" (60.2 cm) to 45.3" (115 cm). This simplifies ordering for you!

Dual rail technology.
This KVM tray technology enables the monitor drawer and the keyboard/mouse drawer to move independently of each other. It makes it easy to leave the monitor visible even when a server cabinet is closed and the keyboard/mouse drawer is fully retracted. Black Box has added switching controls to the monitor bezel that can be used to control an attached switch without pulling open the keyboard/mouse drawer for even more space-saving benefits.

Additionally, the dual rails provide a great monitoring environment without disturbing your cooling system.

You asked for it.
Our latest KVM trays, the ServView V KVM Drawer and ServView V KVM Drawer with Widescreen (KVT517A, etc.) were designed based on feedback we have received from some of our customers.

On the front panel of the tray, there is an LED panel, which helps you locate the ?drawer when it’s closed in a darkened data center. The tray only takes up 1U of rack space, and it features the dual rail technology described earlier.

We added front-panel controls for switching, so if you choose a model with an embedded KVM switch, you can use the buttons on the monitor bezel without pulling out the keyboard. Additionally, the top of the keyboard tray features a hideaway connection for USB wireless devices, such as RF- or Bluetooth® supported keyboards and mice. You can wirelessly access your attached targets, even without opening the cabinet door!

Another feature is the front-panel USB port, which provides crash cart access. If your keyboard or GlidePoint® mouse quit on you, simply use this port to attach a passthrough pointing device.

Finally, the widescreen version supports 1920 x 1080 resolutions and DVI connections — two firsts in the data center. 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


Black Box Explains...Coax connectors.

The BNC (Bayonet-Neill-Concelman) connector is the most commonly used coax connector. This large ”bayonet“ connector features a slotted outer conductor and an inner plastic dielectric, and it offers easy connection... more/see it nowand disconnection. After insertion, the plug is turned, tightening the pins in the socket. It is widely used in video and Radio Frequency (RF) applications up to 2.4 GHz. It is also common in 10BASE2 Ethernet networks, on cable interconnections, network cards, and test equipment.

The TNC connector is a threaded version of the BNC connector. It works in frequencies up to 12 GHz. It‘s commonly used in cellular telephone RF/antenna applications.

The N connector is a larger, threaded connector that was designed in the 1940s for military systems operating at less than 5 GHz. In the 1960s, improvements raised performance to 12 GHz. The connector features an internal gasket and is hand tightened. It is common on 2.4-GHz antennas.

The UHF connector looks like a coarse-threaded, big center-conductor version of the N connector. It was developed in the 1930s. It is suitable for use up to 200–300 MHz and generally offers nonconstant impedance.

The F connector is most often used in cable and satellite TV and antenna applications; and it performs well at high frequencies. The connector has a 3/8–32 coupling thread. Some F connectors are also available in a screw-on style.

The SMA (Subminiature A) connector is one of the most common RF/microwave connectors. This small, threaded connector is used on small cables that won’t be connected and disconnected often. It’s designed for use to 12.4 GHz, but works well at 18, and sometimes even up to 24 GHz. This connector is often used in avionics, radar, and microwave communications.

The SMC (Subminiature C) connector is a small, screw-on version of the SMA. It uses a 10–32 threaded interface and can be used in frequencies up to 10 GHz. This connector is used primarily in microwave environments.

The SMB (Subminiature B) connector is a small version of the SMC connector. It was developed in the 1960s and features a snap-on coupling for fast connections. It features a self-centering outer spring and overlapping dielectric. It is rated from 2–4 GHZ, but can possibly work up to 10 GHz.

The MCX (Micro Coax) connector is a coax RF connector developed in the 1980s. It has a snap-on interface and uses the same inner contact and insulator as the SMB connector but is 30% smaller. It can be used in broadband applications up to 6 GHz. collapse


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


Black Box Explains...SFP, SFP+, and XFP transceivers.

SFP, SFP+, and XFP are all terms for a type of transceiver that plugs into a special port on a switch or other network device to convert the port to... more/see it nowa copper or fiber interface. These compact transceivers replace the older, bulkier GBIC interface. Although these devices are available in copper, their most common use is to add fiber ports. Fiber options include multimode and single-mode fiber in a variety of wavelengths covering distances of up to 120 kilometers (about 75 miles), as well as WDM fiber, which uses two separate wavelengths to both send and receive data on a single fiber strand.

SFPs support speeds up to 4.25 Gbps and are generally used for Fast Ethernet or Gigabit Ethernet applications. The expanded SFP standard, SFP+, supports speeds of 10 Gbps or higher over fiber. XFP is a separate standard that also supports 10-Gbps speeds. The primary difference between SFP+ and the slightly older XFP standard is that SFP+ moves the chip for clock and data recovery into a line card on the host device. This makes an SFP+ smaller than an XFP, enabling greater port density.

Because all these compact transcievers are hot-swappable, there’s no need to shut down a switch to swap out a module—it’s easy to change interfaces on the fly for upgrades and maintenance.

Another characteristic shared by this group of transcievers is that they’re OSI Layer 1 devices—they’re transparent to data and do not examine or alter data in any way. Although they’re primarily used with Ethernet, they’re also compatible with uncommon or legacy standards such as Fibre Channel, ATM, SONET, or Token Ring.

Formats for SFP, SFP+, and XFP transceivers have been standardized by multisource agreements (MSAs) between manufacturers, so physical dimensions, connectors, and signaling are consistent and interchangeable. Be aware though that some major manufacturers, notably Cisco, sell network devices with slots that lock out transceivers from other vendors. collapse


Black Box Explains... Buffers

A buffer (also called a spooler or a cache) is a temporary storage device used to share printers and compensate for a difference in speed and data flow between two... more/see it nowdevices. Buffers use RAM (Random-Access Memory) to take in data and hold it until the receiving device handles it.

A buffer serving a computer can be installed either internally or externally. Internal computer buffers are common in the forms of keyboard inputs, data caches, and video memory. An external buffer is usually used for printing.

An external buffer downloads jobs to the printer, freeing the computer so you can get back to work sooner.

A print buffer’s ports can be serial, parallel, or serial and parallel. Because a buffer’s ports operate independently of each other, a buffer also can be made to perform serial-to-parallel or parallel-to-serial conversion or to change the word structure and/or serial data rate (baud rate) of the data.

While most buffers are FIFO (First In, First Out), some advanced units can function as random-access buffers. For most serial buffers, hardware flow control is required, but some also support software (X-ON/X-OFF) control. Most buffers support printing of multiple copies of a document, provided the buffer has enough memory to store the entire print job. collapse


Black Box Explains...Power over Ethernet (PoE).

What is PoE?
The seemingly universal network connection, twisted-pair Ethernet cable, has another role to play, providing electrical power to low-wattage electrical devices. Power over Ethernet (PoE) was ratified by the... more/see it nowInstitute of Electrical and Electronic Engineers (IEEE) in June 2000 as the 802.3af-2003 standard. It defines the specifications for low-level power delivery—roughly 13 watts at 48 VDC—over twisted-pair Ethernet cable to PoE-enabled devices such as IP telephones, wireless access points, Web cameras, and audio speakers.

Recently, the basic 802.3af standard was joined by the IEEE 802.3at PoE standard (also called PoE+ or PoE plus), ratified on September 11, 2009, which supplies up to 25 watts to larger, more power-hungry devices. 802.3at is backwards compatible with 802.3af.

How does PoE work?
The way it works is simple. Ethernet cable that meets CAT5 (or better) standards consists of four twisted pairs of cable, and PoE sends power over these pairs to PoE-enabled devices. In one method, two wire pairs are used to transmit data, and the remaining two pairs are used for power. In the other method, power and data are sent over the same pair.

When the same pair is used for both power and data, the power and data transmissions don’t interfere with each other. Because electricity and data function at opposite ends of the frequency spectrum, they can travel over the same cable. Electricity has a low frequency of 60 Hz or less, and data transmissions have frequencies that can range from 10 million to 100 million Hz.

Basic structure.
There are two types of devices involved in PoE configurations: Power Sourcing Equipment (PSE) and Powered Devices (PD).

PSEs, which include end-span and mid-span devices, provide power to PDs over the Ethernet cable. An end-span device is often a PoE-enabled network switch that’s designed to supply power directly to the cable from each port. The setup would look something like this:

End-span device → Ethernet with power

A mid-span device is inserted between a non-PoE device and the network, and it supplies power from that juncture. Here is a rough schematic of that setup:

Non-PoE switch → Ethernet without PoE → Mid-span device → Ethernet with power

Power injectors, a third type of PSE, supply power to a specific point on the network while the other network segments remain without power.

PDs are pieces of equipment like surveillance cameras, sensors, wireless access points, and any other devices that operate on PoE.

PoE applications and benefits.

  • Use one set of twisted-pair wires for both data and low-wattage appliances.
  • In addition to the applications noted above, PoE also works well for video surveillance, building management, retail video kiosks, smart signs, vending machines, and retail point-of-information systems.
  • Save money by eliminating the need to run electrical wiring.
  • Easily move an appliance with minimal disruption.
  • If your LAN is protected from power failure by a UPS, the PoE devices connected to your LAN are also protected from power failure.

  • PoE Standards PoE
    IEEE 802.3 af
    PoE IEEE 802.3 at
    Power available at powered device 12.95 W 25.5
    Maximum power delivered 15.40 W 34.20
    Voltage range at powred source 44.0-57.0 V 50.0-57.0 V
    Voltage range at powred device 37.0-57.0 42.5-57.0 V
    Maximum current 350 mA 600 mA
    Maximum cable resistance 20 ohms 12.5 ohms
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