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Black Box Explains...The 13W3 connector.

The 13W3 connector, also called a 13C3 or DB13W3 connector, is an unusual connector that combines a 10-pin D-shell with three analog video conductors. It supports very-high-resolution analog video signals... more/see it nowand has been used by Sun Microsystems®, SGI, NeXt, Intergraph, and other manufacturers. Although 13W3 connectors from different manufacturers look the same, they may be pinned differently.

Pinning for a standard Sun® 13W3 connector:
A1: Red
A2: Green/Gray
A3: Blue
1: Ground*
2: Vertical Sync*
3: Sense 2
4: Sense Ground
5: Composite Sync 
6: Horizontal Sync*
7: Ground*
8: Sense 1
9: Sense 0
10: Composite Ground

* Considered obsolete; may not be connected. collapse


Black Box Explains…Liquid cooling.

The trend toward high-density installations with higher-powered CPUs has made heat a critical issue in data centers. Blade servers present a special challenge—a rack of blade servers can dissipate more... more/see it nowthan 25 kW, generating more heat than an electric oven.

Heat-generated problems
The heat generated in today’s high-density data centers can shorten equipment lifespan, negatively affect equipment performance, and cause downtime. Traditional air-cooling methods such as hot/cold aisle arrangements simply can’t keep up with these heat-generating installations. Data center managers often try to compensate for the inefficiency of air cooling by under-populating racks, but this wastes space—an often scarce commodity in modern data centers.

Why liquid
Because of the inherent inefficiencies of air cooling, many data centers have turned to liquid cooling through water or other refrigerants. Liquids have far greater heat transfer properties than air—water is 3400 times more efficient than air—and can cool far greater equipment densities.

Liquid cooling is usually done at the rack level using the airflow from the servers to move the heat to a cooling unit where it’s removed by liquid, neutralizing heat at the source before it enters the room. Liquid cooling may also be done at the component level, where cooling liquid is delivered directly to individual components. Liquid cooling may also arrive in the form of portable units for cooling hot spots.

Liquid cooling options
Types of liquid cooling commonly used in data centers include:

  • Cabinet-door liquid cooling: With this method, cooling units are special cabinet doors that contain sealed tubes filled with chilled liquid. The liquid is circulated through the door to remove heat vented by equipment fans. Because liquid-cooled doors can replace standard cabinet doors, they’re the favored method for retrofitting liquid cooling into existing data centers.
  • Integrated liquid cooling: This consists of a specialized sealed cabinet that has channels for liquid cooling built into it to act as heat exchangers. Fans move hot air past the heat exchangers before sending the cooled air back to the servers. These cabinets are closed systems that release very little heat into the room.
  • Component-based liquid cooling: Some servers are preconfigured with integrated liquid-based cooling modules. After the servers are installed, liquid is circulated through the cooling modules.
  • Immersion cooling: This rather counterintuitive cooling method immerses servers in a non-conductive liquid, which is circulated to cool the servers.
  • Portable liquid cooling: These are small units that operate by blowing air across water-cooled coils. They can usually accept water from any source—including a nearby faucet. They’re generally plumbed with ordinary garden hoses and require no special skills to use. Portable cooling units are intended for emergency cooling rather than as a permanent solution.


Liquid cooling requires a shift in the way you think about cooling. Installation may require that you acquire a new skill set or hire a professional installer. However, the space savings and cost savings gained through liquid cooling more than make up for the inconvenience of installing a new cooling technology.

Not only does liquid cooling enable data centers to operate at far greater densities than conventional air cooling does, it gets rid of the infrastructure associated with air cooling, enabling you to eliminate hot/cold aisles and raised floors. Liquid cooling can support from 25 to 80% more equipment in the same footprint, resulting in significantly lower infrastructure costs.

Add to this the fact that cooling is often the majority of a data center’s operating cost, and it’s plain to see why an investment in the efficiency of liquid cooling goes right to the bottom line. collapse


Black Box Explains...The fully accessorized rack.

After you choose your rack, consider how you’ll set it up and what accessories you might need.

Your rack may need to be secured. A typical rack has about a... more/see it now15"-deep base, providing some stability, but not enough to prevent the rack from tipping if heavy objects are mounted on it. To solve this problem, most rack bases can be bolted to the floor.

You also need to decide how to accommodate standalone equipment, which is not actually rackmounted or bolted to the rack. You can place small devices on a cantilevered shelf such as the RM001, however, you should place heavier items such as monitors on a center-weight shelf such as the RM377.

Small extras, such as Patch Panel Hinge Kits, can make your job easier. These hinges enable you to access the back of a patch panel simply by swinging it out from the rack. They’re particularly useful for racks in hard-to-reach areas.

If you need to mount both 19" and 23" equipment in the same rack, use a 23" rack with 23"-to-19" Rackmount Adapters to fit the 19" devices.

For a neater appearance, you can cover unused spaces in a rack with Filler Panels.

Cable management is also an important consideration. Our Horizontal and Vertical Cable Managers help you to route cables along the sides of racks, between racks, and to the rackmounted equipment. collapse


Black Box Explains...Component video.

Traditional Composite video standards—NTSC, PAL, or SECAM—combine luminance (brightness), chrominance (color), blanking pulses, sync pulses, and color burst information into a single signal.

Another video standard—S-Video—separates luminance from chrominance to provide... more/see it nowsome improvement in video quality.

But there’s a new kind of video called Component video appearing in many high-end video devices such as TVs and DVD players. Component video is an advanced digital format that separates chrominance, luminance, and synchronization into separate signals. It provides images with higher resolution and better color quality than either traditional Composite video or S-Video. There are two kinds of Component video: Y-Cb-Cr and Y-Pb-Pr. Y-Cb-Cr is often used by high-end DVD players. HDTV decoders typically use the Y-Pb-Pr Component video signal.

Many of today’s high-end video devices such as plasma televisions and DVD players actually have three sets of video connectors: Composite, S-Video, and Component. The easiest way to improve picture quality on your high-end TV is to simply connect it using the Component video connectors rather than the Composite or S-Video connectors. Using the Component video connection enables your TV to make use of the full range of video signals provided by your DVD player or cable box, giving you a sharper image and truer colors.

To use the Component video built into your video devices, all you need is the right cable. A Component video cable has three color-coded BNC connections at each end. For best image quality, choose a high-quality cable with adequate shielding and gold-plated connectors. collapse


Black Box Explains...Why media converters need SNMP.

The number of Ethernet switches and fiber optic segments being added to Ethernet networks keeps increasing. And as long as most Ethernet switches are only available with 10BASE-T and 100BASE-TX... more/see it nowinterfaces, media converters will remain in demand.

Until now, a failure on the network could go unnoticed. Once a failure was detected, it could take a long time to isolate it, especially if a technician had to be sent to the site. But media converters with SNMP eliminate some of the guesswork.

With SNMP, the IS manager can detect a failure, isolate it to a specific port, and determine what hardware is required to repair it. A technician can then be sent directly to the right place to fix faulty hardware or repair a broken cable.

SNMP enables you to set up alarms or traps when a link is down. You can turn features on and off from a central terminal, so there’s no need to leave your desk. You can also monitor power supplies and replace them without interrupting service. SNMP management reduces the time and money it takes to get your network up and running again. The users on your network will notice—and appreciate—the improved service and reliability. collapse


Black Box Explains...Dry contacts.

A dry contact, also called a volt-free contact, is a relay contact that does not supply voltage. The relay energizes or de-energizes when a change to its input has occurred.... more/see it nowIn other words, a dry contact simply detects whether or not an input switch is open or closed.

The dry contacts in the ServSensor Contact provide a simple two-wire interface that can be easily adapted to third-party sensors and devices. Because you define what the open or closed condition means, dry contacts are infinitely adaptable.

Use dry contacts to monitor alarms such as fire alarms, burglar alarms, and alarms on power systems such as UPSs. A very common use for dry contacts is to detect whether a cabinet door is open or closed. collapse


Black Box Explains...Type 1 vs. Type 6 Cable

Type 1 Cable is made of solid wire, typically 22 AWG bare copper. It has braided shielding around each pair. It’s recommended for long runs in walls, conduits, etc.

Type 6... more/see it nowCable is typically made of 26 AWG stranded copper and has one shield around both pairs. It’s lighter and more flexible than Type 1 Cable and has a better “look.” It’s recommended for use in office environments. collapse


Black Box Explains...Advanced printer switches.

Matrix—A matrix switch is a switch with a keypad for selecting one of many input ports to connect to any one of many output ports.

Port-Contention—A port-contention switch is an... more/see it nowautomatic electronic switch that can be serial or parallel. It has multiple input ports but only one output port. The switch monitors all ports simultaneously. When a port receives data, it prints and all the other ports have to wait.

Scanning—A scanning switch is like a port-contention switch, but it scans ports one at a time to find one that’s sending data.

Code-Operated—Code-operated switches receive a code (data string) from a PC or terminal to select a port.

Matrix Code-Operated—This matrix version of the code-operated switch can be an any-port to any-port switch. This means than any port on the switch can attach to any other port or any two or more ports can make a simultaneous link and transfer data. collapse


Black Box Explains...Microphone positioning.

Proper microphone positioning is especially important to take advantage of noise canceling microphones, which reject background noise.

For optimum performance, position the microphone one finger width away from your lower lip.


Black Box Explains...T1 and E1.

If you manage a heavy-traffic data network and demand high bandwidth for high speeds, you need digital super-fast T1 or E1.

Both T1 and E1 are foundations of global communications. Developed... more/see it nowmore than 35 years ago and commercially available since 1983, T1 and E1 go virtually anywhere phone lines go, but they’re much faster. T1, used primarily in the U.S., sends data up to 1.544 Mbps; E1, used primarily in Europe, supports speeds to 2.048 Mbps. No matter where you need to connect—North, South, or Central America, Europe, or the Pacific Rim—T1 and E1 can get your data there fast!

T1 and E1 are versatile, too. Drive a private, point-to-point line; provide corporate access to the Internet; enable inbound access to your Web Server—even support a voice/data/fax/video WAN that extends halfway around the world! T1 and E1 are typically used for:
• Accessing public Frame Relay networks or Public Switched Telephone Networks (PSTNs) for voice or fax.
• Merging voice and data traffic. A single T1 or E1 line can support voice and data simultaneously.
• Making super-fast LAN connections. Today’s faster Ethernet speeds require the very high throughput provided by one or more T1 or E1 lines.
• Sending bandwidth-intensive data such as CAD/CAM, MRI, CAT-scan images, and other large files.

Scaling T1
Basic T1 service supplies a bandwidth of 1.536 Mbps. However, many of today’s applications demand much more bandwidth. Or perhaps you only need a portion of the 1.536 Mbps that T1 supplies. One of T1’s best features is that it can be scaled up or down to provide just the right amount of bandwidth for any application.

A T1 channel consists of 24 64-kbps DS0 (Digital Signal [Zero]) subchannels that combine to provide 1.536 Mbps throughput. Because they enable you to combine T1 lines or to use only part of a T1, DS0s make T1 a very flexible standard.

If you don’t need 1.536 Mbps, your T1 service provider can rent you a portion of a T1 line, called Fractional T1. For instance, you can contract for half a T1 line—768 kbps—and get the use of DS0s 1–12. The service provider is then free to sell DS0s 13–24 to another customer.

If you require more than 1.536 Mbps, two or more T1 lines can be combined to provide very-high-speed throughput. The next step up from T1 is T1C; it offers two T1 lines multiplexed together for a total throughput of 3.152 on 48 DS0s. Or consider T2 and get 6.312 Mbps over 96 DS0s by multiplexing four T1 lines together to form one high-speed connection.

Moving up the scale of high-speed T1 services is T3. T3 is 28 T1 lines multiplexed together for a blazing throughput of 44.736 Mbps, consisting of 672 DS0s, each of which supports 64 kbps.

Finally there’s T4. It consists of 4032 64-kbps DS0 subchannels for a whopping 274.176 Mbps of bandwidth—that’s 168 times the size of a single T1 line!

These various levels of T1 service can by implemented simulta-neously within a large enterprise network. Of course, this has the potential to become somewhat overwhelming from a management standpoint. But as long as you keep track of DS0s, you always know exactly how much bandwidth you have at your disposal.

T1’s cousin, E1, can also have multiple lines merged to provide greater throughput. collapse

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