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Black Box Explains...Insertion loss.

Insertion loss is a power loss that results from inserting a component into a previously continuous path or creating a splice in it. It is measured by the amount of... more/see it nowpower received before and after the insertion.

In copper cable, insertion loss measures electrical power lost from the beginning of the run to the end.

In fiber cable, insertion loss (also called optical loss) measures the amount of light lost from beginning to end. Light can be lost many ways: absorption, diffusion, scattering, dispersion, and more. It can also be from poor connections and splices in which the fibers don’t align properly.

Light loss is measured in decibels (dBs), which indicate relative power. A loss of 10 dB means a tenfold reduction in power.

Light strength can be measured with optical power meters, optical loss test sets, and other test sets that send a known light source through the fiber and measure its strength on the other end. collapse

Black Box Explains... Multiplatform cabling environments.

When using a ServSwitch™ with multiple computer platforms, choosing which peripherals to use to control your diverse group of CPUs can be confusing. Because of the wide variation in connector... more/see it nowtypes and compatibilities, there is a hierarchy to follow when choosing your “user station“ keyboard, monitor, and mouse.

1. If you have at least one Sun® computer in your application, you should use a Sun keyboard and mouse to control your CPUs.

2. If you have a mixture of PCs and Mac® computers, use your PC-style keyboard and mouse to control your CPUs. collapse

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

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

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

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

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

Black Box Explains... Standard and ThinNet Ethernet cabling.

The Ethernet standard supports 10-, 100-, and 1000-Mbps speeds. It supports both half- and full-duplex configurations over twisted-pair and fiber cable, as well as half-duplex over coax cable.

However, the Thick... more/see it nowand ThinNet Ethernet standards support only 10-Mbps speeds.

Standard (Thick) Ethernet (10BASE5)
• Uses “Thick” coax cable with N-type connectors for a backbone and a transceiver cable with 15-pin connectors from the transceiver to the network interface card.
• The maximum number of segments is five, but only three can have computers attached. The others are for network extension.
• The maximum length of one segment is 500 meters.
• The maximum total length of all segments is 2500 meters.
• The maximum length of one transceiver cable is 50 meters.
• The minimum distance between transceivers is 2.5 meters.
• No more than 100 transceiver connections per segment are allowed. A repeater counts as a station for both segments.

Thin Ethernet (ThinNet) (10BASE2)
• Uses “Thin” coax cable (RG-58A/U or RG-58C/U).
• The maximum length of one segment is 185 meters.
• The maximum number of segments is five.
• The maximum total length of all segments is 925 meters.
• The minimum distance between T-connectors is 0.5 meters.
• No more than 30 connections per segment are allowed.
• T-connectors must be plugged directly into each device. collapse

Black Box Explains…Sizing a UPS

The power delivered by a UPS is usually expressed both in volt-amps (VA) and watts. There’s often confusion about what the difference is between these figures and how to use... more/see it nowthem to select a UPS.

VA is power voltage multiplied by amps. For instance, a device that draws 5 amps of 120-volt power has a VA of 600. Watts is a measure of the actual power used by the device. VA and watts may be the same. The formula for watts is often expressed as:

Watts = Volts x Amps

This formula would lead you to believe that a measurement of VA is equal to watts, and it’s true for DC power. AC power, however, can get complicated. Some AC devices have a VA that’s higher than watts. VA is the power a device seems to be consuming, while watts is the power it actually uses.

This requires an adjustment called a power factor, which is the ratio of watts to VA.

AC Watts = Volts x Amps x Power Factor


Watts/VA = Power Factor

Simple AC devices, such as light bulbs, typically have a power factor of 100% (which may also be expressed as 1), meaning that watts are equal to VA like they are with DC devices. Computers have had a much lower power factor, traditionally in the 60–70% range. This meant that only part of the power going into the computer was being used to do useful work.

Today, however, because of Energy Star requirements, virtually all computing devices are power factor corrected and have a power factor of more than 90%.

Which brings us around to how to use this information to select a UPS. The capacity of a UPS is defined as both VA and watts. Both should be above the power requirements of the connected equipment.

Because of the computers that had a low power factor, UPSs typically had a VA that was much higher than watts, for instance, 500 VA/300 watts. In this case, if you use the UPS with a power factor corrected device that requires 450 VA/400 watts, the UPS won’t provide enough wattage to support the device.

Although UPSs intended for enterprise use now normally have a high power factor, consumer-grade UPSs still typically have a lower power factor—sometimes even under 60%. When using these UPSs, size them by watts, not VA, to ensure that they can support connected equipment.

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...Super Dynamic II.

This proprietary processing technology developed by Panasonic® eliminates backlighting problems commonly seen with security camera systems. It gives you clear images regardless of the lighting situation and a dynamic range... more/see it nowthat’s 64 times greater than that offered by conventional video cameras.
Super Dynamic II™ accomplishes this by using a double-speed, charge-coupled device (CCD). It takes two pictures in the time
it takes for a conventional CCD to capture one. The first Super Dynamic II picture is a long exposure (1⁄60th of a second) that captures a scene’s dark areas; the second is a short exposure (from 1⁄1000th to 1⁄4000th of a second) that captures the scene’s bright areas. Super Dynamic II then combines the best quality signals from the two images and outputs them as a Composite analog image.
The technology’s enhanced Digital Signal Processing (DSP) circuitry corrects gradation to give you proper black level references so black areas within a scene appear black—not washed-out shades of gray. It also enables images with high contrast to be seen on the screen.
What’s more, Super Dynamic II technology provides exceptional sensitivity (0.8 lux using an F1.4 lens), enabling the camera to capture vivid details and color even in low-light applications. collapse

Black Box Explains...Media converters that are really switches.

A media converter is a device that converts from one media type to another, for instance, from twisted pair to fiber to take advantage of fiber’s greater range. A traditional... more/see it nowmedia converter is a two-port Layer 1 device that performs a simple conversion of only the physical interface. It’s transparent to data and doesn't “see” or manipulate data in any way.

An Ethernet switch can also convert one media type to another, but it also creates a separate collision domain for each switch port, so that each packet is routed only to the destination device, rather than around to multiple devices on a network segment. Because switches are “smarter” than traditional media converters, they enable additional features such as multiple ports and copper ports that autosense for speed and duplex.

Switches are beginning to replace traditional 2-port media converters, leading to some fuzziness in terminology. Small 4- or 6-port Ethernet switches are very commonly called media converters. In fact, anytime you see a “Layer 2” media converter or a media converter with more than two ports, it’s really a small Ethernet switch. 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...Beyond T1—other standards for high-speed circuits.

While there are many applications for basic T1 rate service (1.536 Mbps), some applications require much more bandwidth. One of the most attractive features of T1 is the number of... more/see it nowoptions available to accommodate these kinds of demands. The important thing to remember is that all of these higher-speed services operate with the same consistent framing formats as the standard T1 service.

T1 is a high-speed service with a clock speed of 1.544 Mbps. It’s made up of 24 64-kbps DS0 (Digital-Signal [zero]) subchannels that together can support throughput rates of up to 1.536 Mbps. But there are higher levels of T1 service that are also available. For instance, T1C service doubles the T1 rate. It supports 3.152 Mbps with a total of 48 DS0s for top-speed applications. In a T1C environment, two T1 lines are combined into one using a special T1 mux.

The next-highest level of service is called T2. It offers 6.312 Mbps over 96 DS0s by multi-plexing 4 T1 lines into a single high-speed line.

The next two levels of service are exponentially larger than T2. A high-speed T3 trunk line is 28 times larger than a standard T1 line. T3 brings 44.736 Mbps to a customer site via 672 DS0s. This tremendous capacity is made possible by multiplexing 28 T1 lines or combina?tions of T2 and T1 lines.

Finally, T4 service offers a bandwidth potential of 274.176 Mbps, made up of 4032 64-kbps DS0 subchannels. At 168 times the size of a standard 1.544-Mbps line, T4 service dwarfs T1. The physical connections require multiplexing 6 T3 lines or 168 T1 lines into a single high-speed trunk.

With so many incredibly high-speed T-level service options available, system administrators have great flexibility to configure their operations for maximum efficiency and economy.

It’s important to remember that these various levels of T1 services can be implemented simultaneously within a particularly large enterprise to support complex network configurations.

Of course, this kind of application has the potential to become somewhat overwhelming from a management standpoint. However, as long as you keep track of the individual DS0s, you should always be able to accurately gauge how much available bandwidth you have at your disposal. collapse

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