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Black Box Explains... GBICs

A Gigabit Interface Converter (GBIC) is a transceiver that converts digital electrical currents to optical signals and back again. GBICs support speeds of 1 Gbps or more and are typically... more/see it nowused as an interface between a high-speed Ethernet or ATM switch and a fiber backbone. GBICs are hot-swappable, so switches don’t need to be powered down for their installation. collapse


Black Box Explains...Media converters.



Media converters interconnect different cable types such as twisted pair, fiber, and coax within an existing network. They are often used to connect newer Ethernet equipment to legacy cabling.... more/see it nowThey can also be used in pairs to insert a fiber segment into copper networks to increase cabling distances and enhance immunity to electromagnetic interference (EMI).


Traditional media converters are purely Layer 1 devices that only convert electrical signals and physical media. They don’t do anything to the data coming through the link so they’re totally transparent to data. These converters have two ports—one port for each media type. Layer 1 media converters only operate at one speed and cannot, for instance, support both 10-Mbps and 100-Mbps Ethernet.


Some media converters are more advanced Layer 2 Ethernet devices that, like traditional media converters, provide Layer 1 electrical and physical conversion. But, unlike traditional media converters, they also provide Layer 2 services—in other words, they’re really switches. This kind of media converter often has more than two ports, enabling you to, for instance, extend two or more copper links across a single fiber link. They also often feature autosensing ports on the copper side, making them useful for linking segments operating at different speeds.


Media converters are available in standalone models that convert between two different media types and in chassis-based models that connect many different media types in a single housing.




Rent an apartment

Standalone converters convert between two media. But, like a small apartment, they can be outgrown. Consider your current and future applications before selecting a media converter. Standalone converters are available in many configurations, including 10BASE-T to multimode or single-mode fiber, 10BASE-T to Thin coax (ThinNet), 10BASE-T to thick coax (standard Ethernet), CDDI to FDDI, and Thin coax to fiber. 100BASE-T and 100BASE-FX models that connect UTP to single- or multimode fiber are also available. With the development of Gigabit Ethernet (1000 Mbps), media converters have been created to make the transition to high-speed networks easier.




...or buy a house.

Chassis-based or modular media converters are normally rackmountable and have slots that house media converter modules. Like a well-planned house, the chassis gives you room to grow. These are used when many Ethernet segments of different media types need to be connected in a central location. Modules are available for the same conversions performed by the standalone converters, and 10BASE-T, 100BASE-TX, 100BASE-FX, and Gigabit modules may also be mixed.

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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...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...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...HDBaseT

HDBaseT is a connectivity standard for distribution of uncompressed HD multimedia content. HDBaseT technology converges full HD digital video, audio, 100BaseT Ethernet, power over cable, and various control signals through... more/see it nowa single LAN cable. This is referred to as 5Play™, a feature set that sets HDBaseT technology above the current standard.

Video
HDBaseT delivers full HD/3D and 2K/4K uncompressed video to a network of devices or to a single device (point-to-point). HDBaseT supports all key HDMI 1.4 features, including EPG, Consumer Electronic Controls (CEC), EDID, and HDCP. The unique video coding scheme ensure the highest video quality at zero latency.

Audio
As with the video, HDBaseT audio is passed through from the HDMI chipset. All standard formats are supported, including Dolby Digital, DTS, Dolby TrueHD, DTS HD-Master Audio.

Ethernet
HDBaseT supports 100Mb Ethernet, which enables communications between electronic devices including televisions, sound systems, computers, and more. Additionally, Ethernet support enables access to any stored multimedia content (such as video or music streaming).

Control
HDBaseT's wide range of control options include CEC, RS-232, and infrared (IR). IP control is enabled through Ethernet channel support.

Power
The same cable that delivers video, audio, Ethernet, and control can deliver up to 100W of DC power. This means users can place equipment where one wants to, not just those locations with an available power source. HDBaseT Architecture
HDBaseT sends video, audio, Ethernet, and control from the source to the display, but only transfers 100Mb of data from display to source (Ethernet and control data). The asymmetric nature of HDBaseT is based on a digital signal processing (DSP) engine and an application front end (AFE) architecture.

HDBaseT uses a proprietary version of Pulse Amplitude Modulation (PAM) technology, where digital data is represented as a coding scheme using different levels of DC voltage at high rates. This special coding provides a better transfer quality to some kinds of data without the need to "pay" the protecting overhead for the video content, which consumes most of the bandwidth. HDBaseT PAM technology enables the 5Play feature-set to be maintained over a single 330-foot (100 m) CAT cable without the electrical characteristics of the wire affecting performance.

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Black Box Explains... SC and ST connectors.

The SC Connector features a molded body and a push-pull locking system. It’s perfect for the office, CATV, and telephone applications.

The ST® Connector uses a bayonet locking system. Its... more/see it nowceramic ferrule ensures high performance. collapse


Black Box Explains...Choosing cabinets and racks.



Why cabinets? Why racks?


A cabinet is an enclosure with a door (or doors); a rack is an open frame. There are several things you... more/see it nowshould consider when you’re deciding whether you need an enclosed cabinet or a rack.


First, what equipment will you be putting in it? The extra stability of a cabinet might be important if you’re installing large, heavy equipment like servers. But if you need frequent access to all sides of the equipment, an open rack might be more convenient. And if your equipment needs a lot of ventilation, you’ll have to be more careful about the air supply if you enclose it in a cabinet.


Second, in what environment will you be installing it? If the environment is open or dusty, for example, you might need the extra protection of an enclosed cabinet. On the other hand, a rack might be perfectly adequate in a well-maintained data center.


Don’t neglect aesthetics. Will customers or clients see your installation? A cabinet with a door looks much neater than an open rack. When you’re trying to create a professional image, everything counts.


Finally, there’s security. An enclosed cabinet can be locked with a simple lock and key.


On the other hand, there are advantages to open racks, too. It’s easier to get at all sides of the equipment. But you’ll have to take other steps to keep the equipment secure-keeping it in a locked room, for example.


Both cabinets and racks come in all sizes and in many different installation styles. Some are freestanding; some are designed to be mounted on a wall. Others sit on the floor but attach to the wall for more stability.


If you need to set up your installation in a hurry, you can order a preassembled cabinet. You’re ready to load your equipment as soon as the cabinet arrives.


Choosing the right server cabinet.

Consider this quick checklist of features when choosing a server cabinet:

  • High-volume airflow. The requirements for additional airflow increase as more servers are mounted in a cabinet. Additionally, manufacturers are making servers narrower to increase available space. But with more servers in the same amount of space, heat buildup is frequently a problem.
  • Extra depth to accommodate newer, deeper servers.
  • Adjustable rails.
  • Rails with M6 square holes. Although 10-32 tapped and drilled holes are sometimes still required, newer hardware has M6 square holes. Know which type of mounting equipment you’ll need.
  • Front and/or rear accessibility.
NEMA 12 certification.

The National Electrical Manufacturers’ Association (NEMA) specifies guidelines for cabinet certifications. NEMA 12 cabinets are constructed for indoor use to provide protection against certain contaminants that might come in contact with the enclosed equipment. The NEMA 12 designation means a particular cabinet has met the guidelines, which include protection against falling dirt, circulating dust, lint, fibers, and dripping or splashing liquids. Protection against oil and coolant seepage is also a prerequisite for NEMA 12 certification.


Organizations with mission-critical equipment benefit from a NEMA 12 cabinet. Certain environments put equipment at a higher risk than others. For example, equipment in industrial plants is subject to varying degrees of extreme temperature. Even office buildings generate lots of dust and moisture, which is detrimental to equipment. NEMA 12 enclosures help to ensure that your operation suffers from as little downtime as possible.


Choosing the right rack.

Before you choose a rack, you have to determine what equipment you need to house. This list can include CPUs, monitors, keyboards, modems, servers, switches, hubs, routers, and UPSs. Consider the size and weight of all your equipment as well. The rack must be large and strong enough to hold everything you have now, and you’ll also want to leave extra room for growth.

Most racks are designed to hold equipment that’s 19" (48.3 cm) wide. But height and depth may vary from rack to rack. Common rack heights range from 39" (99.1 cm) to 87" (221 cm).


Another measurement you should know about is the rack unit. One rack unit, abbreviated as U, equals 1.75" (4.4 cm). A rack that is 20U, for example, has 20 rack spaces for equipment, or is 35" high (88.9 cm).


Understanding cabinet and rack measurements.

The main component of a cabinet or rack is a set of vertical rails with mounting holes to which you attach your equipment or shelves. When you consider the width or height of the rack, clarify whether they are inside or outside dimensions.

The first measurement you need to know is the width between the rails. The most common size is 19 inches with hole-to-hole centers measuring 18.3 inches. But there are also 23-inch and 24-inch cabinets and racks. Most rackmount equipment is made to fit 19-inch rails but can be adapted to fit wider rails.


After the width, the most important specification is the number of rack units, abbreviated “U.” It’s a measurement of vertical space available on the rails. Because the width is standard, the amount of vertical space is what determines how much equipment you can actually install. Remember that this measurement of usable vertical space is smaller than the external height of the cabinet or rack.


One rack unit (1U) is 1.75 inches of usable vertical space. So, for example, a rackmount device that’s 2U high will take up 3.5 inches of rack space. A rack that’s 20U high will have 35 inches of usable space.

Because both racks and the equipment that fit in them are usually measured in rack units, it’s easy to figure out how much equipment you can fit in a given cabinet or rack.



Do you need a fan?

Even if your cabinet or rack is in a climate-controlled room, the equipment in it can generate a lot of heat. You may want to consider adding a fan to help keep your equipment from overheating. It’s especially important to have adequate ventilation in an enclosed cabinet.


Getting power to your equipment.

Unless you want to live in a forest of extension cords, you’ll need one or more power strips. Some cabinets come with power strips built in.


If you need to order a power strip, consider which kind will be best for your installation. Rackmount power strips come in versions that mount either vertically or horizontally. Some have outlets that are spaced widely to accommodate transformer blocks-a useful feature if your equipment uses bulky power transformers.


Surge protection is another important issue. Some power strips have built-in surge protection; some don’t. With all the money you have invested in rackmount equipment, you’ll certainly want to make sure it’s protected.


Any mission-critical equipment should also be connected to an uninterruptible power supply (UPS). A UPS keeps your equipment from crashing during a brief blackout or brownout and gives you enough time to shut down everything properly in an extended power outage. You can choose a rackmount UPS for the most critical equipment, or you can plug the whole rack into a standalone UPS.


Managing the cables.

Your equipment may look very tidy when it’s neatly stacked in a cabinet. But you still have an opportunity to make a mess once you start connecting it all. Unless you’re very careful with your cables, you can create a rat’s nest you’ll never be able to sort out.


There are many cabinet and rack accessories that can simplify cable organization. We have Cable Management Guides, Rackmount Cable Raceways, Horizontal Covered Organizers, Vertical Cable Organizers, Horizontal Wire Ring Panels, and Cable Manager Hangers-all designed to help you manage your cables more easily.


Plotting your connections in advance helps you to decide how to organize the cables. Knowing where the connectors are on your equipment tells you where it’s most efficient to run cables horizontally and where it’s better to run them vertically.

The important thing is to have a plan. Most network problems are in the cabling, so if you let your cables get away from you now, you’re sure to pay for it down the road.


Asking for help.

When you’re setting up a cabinet or rack, you have a lot of different factors to consider. Black Box Tech Support is always happy to help you figure out what you need and how to put it together. For cabinets and racks solutions, call our Connectivity Group at 724-746-5500, press 1, 2, 2.

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SHDSL, VDSL, VDSL2, ADSL, and SDSL.

xDSL, a term that encompasses the broad range of digital subscriber line (DSL) services, offers a low-cost, high-speed data transport option for both individuals and businesses, particularly in areas without... more/see it nowaccess to cable Internet.

xDSL provides data transmission over copper lines, using the local loop, the existing outside-plant telephone cable network that runs right to your home or office. DSL technology is relatively cheap and reliable.

SHDSL can be used effectively in enterprise LAN applications. When interconnecting sites on a corporate campus, buildings and network devices often lie beyond the reach of a standard Ethernet segment. Now you can use existing copper network infrastructure to connect remote LANS across longer distances and at higher speeds than previously thought possible.

There are various forms of DSL technologies, all of which face distance issues. The quality of the signals goes down with increasing distance. The most common will be examined here, including SHDSL, ADSL, and SDSL.

SHDSL (also known as G.SHDSL) (Single-Pair, High-Speed Digital Subscriber Line) transmits data at much higher speeds than older versions of DSL. It enables faster transmission and connections to the Internet over regular copper telephone lines than traditional voice modems can provide. Support of symmetrical data rates makes SHDSL a popular choice for businesses for PBXs, private networks, web hosting, and other services.

Ratified as a standard in 2001, SHDSL combines ADSL and SDSL features for communications over two or four (multiplexed) copper wires. SHDSL provides symmetrical upstream and downstream transmission with rates ranging from 192 kbps to 2.3 Mbps. As a departure from older DSL services designed to provide higher downstream speeds, SHDSL specified higher upstream rates, too. Higher transmission rates of 384 kbps to 4.6 Mbps can be achieved using two to four copper pairs. The distance varies according to the loop rate and noise conditions.

For higher-bandwidth symmetric links, newer G.SHDSL devices for 4-wire applications support 10-Mbps rates at distances up to 1.3 miles (2 km). Equipment for 2-wire deployments can transmit up to 5.7 Mbps at the same distance.

SHDSL (G.SHDSL) is the first DSL standard to be developed from the ground up and to be approved by the International Telecommunication Union (ITU) as a standard for symmetrical digital subscriber lines. It incorporates features of other DSL technologies, such as ADSL and SDS, and is specified in the ITU recommendation G.991.2.

Also approved in 2001, VDSL (Very High Bitrate DSL) as a DSL service allows for downstream/upstream rates up to 52 Mbps/16 Mbps. Extenders for local networks boast 100-Mbps/60-Mbps speeds when communicating at distances up to 500 feet (152.4 m) over a single voice-grade twisted pair. As a broadband solution, VDSL enables the simultaneous transmission of voice, data, and video, including HDTV, video on demand, and high-quality videoconferencing. Depending on the application, you can set VDSL to run symmetrically or asymmetrically.

VDSL2 (Very High Bitrate DSL 2), standardized in 2006, provides a higher bandwidth (up to 30 MHz) and higher symmetrical speeds than VDSL, enabling its use for Triple Play services (data, video, voice) at longer distances. While VDSL2 supports upstream/downstream rates similar to VDSL, at longer distances, the speeds don’t fall off as much as those transmitted with ordinary VDSL equipment.

ADSL (Asymmetric DSL) provides transmission speeds ranging from downstream/upstream rates of 9 Mbps/640 kbps over a relatively short distance to 1.544 Mbps/16 kbps as far away as 18,000 feet. The former speeds are more suited to a business, the latter more to the computing needs of a residential customer.

More bandwidth is usually required for downstream transmissions, such as receiving data from a host computer or downloading multimedia files. ADSL’s asymmetrical nature provides more than sufficient bandwidth for these applications.

The lopsided nature of ADSL is what makes it most likely to be used for high-speed Internet access. And the various speed/distance options available within this range are one more point in ADSL’s favor. Like most DSL services standardized by ANSI as T1.413, ADSL enables you to lease and pay for only the bandwidth you need.

SDSL (Symmetric DSL) represents the two-wire version of HDSL—which is actually symmetric DSL, albeit a four-wire version. SDSL is also known within ANSI as HDSL2.

Essentially offering the same capabilities as HDSL, SDSL offers T1 rates (1.544 Mbps) at ranges up to 10,000 feet and is primarily designed for business applications.

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Black Box Explains...How a line driver operates.

Driving data? Better check the transmission.

Line drivers can operate in any of four transmission modes: 4-wire full-duplex, 2-wire full-duplex, 4-wire half-duplex, and 2-wire half-duplex. In fact, most models support more... more/see it nowthan one type of operation.

So how do you know which line driver to use in your application?

The deal with duplexing.
First you must decide if you need half- or full-duplex transmission. In half-duplex transmission, voice or data signals are transmitted in only one direction at a time, In full-duplex operation, voice or data signals are transmitted in both directions at the same time. In both scenarios, the communications path support the full data rate.

The entire bandwidth is available for your transmission in half-duplex mode. In full-duplex mode, however, the bandwidth must be split in two because data travels in both directions simultaneously.

Two wires or not two wires? That is the question.
The second consideration you have is the type of twisted-pair cable you need to complete your data transmissions. Generally you need twisted-pair cable with either two or four wires. Often the type of cabling that’s already installed in a building dictates what kind of a line driver you use. For example, if two twisted pairs of UTP cabling are available, you can use a line driver that operates in 4-wire applications, such as the Short-Haul Modem-B Async or the Line Driver-Dual Handshake models. Otherwise, you might choose a line driver that works for 2-wire applications, such as the Short-Haul Modem-B 2W or the Async 2-Wire Short-Haul Modem.

If you have the capabilities to support both 2- and 4-wire operation in half- or full-duplex mode, we even offer line drivers that support all four types of operation.

As always, if you’re still unsure which operational mode will work for your particular applications, consult our Technical Support experts and they’ll help you make your decision. collapse

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