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Cold aisle containment.

Cold aisle containment (CAC) is a cooling method that increases cooling efficiency and reduces energy costs in data centers.

This cooling method relies on the fact that most network equipment... more/see it nowand servers are designed to cool themselves by drawing air in through the front and exhausting it out the rear. To implement cold aisle containment, rows of cabinets or racks are arranged facing each other to form aisles, and cool air is routed between the rows. Equipment takes the cool air in at the front of the cabinet and exhausts it out the back into the room.

To keep cool air from mixing with warm air, row ends are closed off with an air-flow barrier. This barrier can range from makeshift arrangements of plastic strips to doors made expressly for this purpose.

Because cold aisle containment concentrates cool air at the front of equipment where it’s most needed, it’s an exceptionally effective cooling method. Cold aisle containment significantly reduces energy costs, lowering power bills as well as reducing data centers’ carbon footprints. 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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    Black Box Explains...Remote access.

    Remote access is the ability to access a network, a personal computer, a server, or other device from a distance for the purpose of controlling it or to access data.... more/see it nowToday, remote access is usually accomplished over the Internet, although a local IP network, telephone lines, cellular service, or leased lines may also be used. With today’s ubiquitous Internet availability, remote access is increasingly popular and often results in significant cost savings by enabling greater network access and reducing travel to remote sites. Remote access is a very general term that covers a wide range of applications from telecommuting to resetting a distant server. Here are just a few of the applications that fall under the remote access umbrella:

    Remote network access
    A common use for remote access is to provide corporate network access to employees who work at home or are in sales or other traveling positions. This kind of remote access typically uses IPsec VPN tunnels to authenticate and secure connections.

    Remote desktop access
    Remote desktop access enables users to access a computer remotely from another computer and take control of it as if it were local. This kind of remote control requires that special software—which is included with most operating systems—be installed and enabled. It’s often used by those who travel frequently to access their “home” computer, and by network administrators for remote server access. This remote access method has some inherent security concerns and is usually incompatible with firewalls, so it’s important to be aware of its limitations and use adequate security precautions.

    Remote KVM access
    A common application in organizations that maintain servers across multiple sites is server administration through an IP-enabled KVM switch. These IP-addressable switches support one or more servers and have an integral Web server, enabling users to access them over the Internet through a Web browser. Because they’re intended for Internet use, these switches offer authentication and encryption for secure connections.

    Remote power management
    Anyone who’s ever had to get out of bed in the middle of the night to go switch a server off and back on again to reset it can appreciate the convenience of remote power management. Remote power managers have a wide range of capabilities ranging from simple power switching to reboot a device to sophisticated power monitoring, reporting, and management functions.

    Remote environmental security monitoring
    Remote environmental and security monitoring over the Internet is increasingly popular, largely because of the cost savings of using existing network infrastructure rather than a proprietary security system. This application requires IP-addressable hubs that support a variety of sensors ranging from temperature and humidity to power monitors. Some models even support surveillance cameras. 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...Choosing a cabinet.

    Understanding cabinet and rack measurements.
    The main component of a cabinet is a set of vertical rails with mounting holes to which you attach your equipment or shelves. When you consider... more/see it nowthe width or height of a cabinet, clarify whether the dimensions are inside or outside.

    The first measurement you need to know is the width of the rails. The most common size is 19 inches with hole-to-hole centers measuring 18.3 inches. 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 for wider rails.

    After width, the most important specification is the number of rack units, abbreviated as “U.” It’s a measurement of space available to mount equipment. Because cabinet width is standard, the amount of space is what determines how much equipment you can actually install. Remember, this is an internal measurement of usable space and is smaller than an external measure of the cabinet or rack.

    One rack unit (1U) is 1.75 inches of usable space and is usually, but not always, measured vertically. So, for example, a rackmount device that’s 2U high takes up 3.5 inches of rack space. A rack that’s 20U high has 35 inches of usable space.

    Choosing the right cabinet.
    Here’s a quick checklist of features to keep in mind before you choose a cabinet for servers or other network devices:
    • High-volume airflow.
    • Adjustable rails.
    • Rails with M6 square holes.
    • Moisture and dust resistance.
    • Air filters.
    • Front and/or rear accessibility.
    • Locking doors.
    • Left- or right-hinging doors.
    • Power strips and cable organizers.
    • Interior lighting.
    • Preassembly.
    • Availability of optional shelves, fans, and casters.
    • Cable management rails, space, and knockouts.
    • Extra depth to accommodate newer, deeper servers.

    Don’t forget to accessorize.
    Even if your cabinet is in a climate-controlled room, you may need to add a fan panel to help keep your equipment from overheating. It’s especially important to have ventilation in an enclosed cabinet.

    Rackmount power strips mount either vertically or horizontally. Some have widely spaced outlets to accommodate transformer blocks. Some power strips include surge protection.

    Mission-critical equipment should be connected to an uninterruptible power supply (UPS). A UPS keeps your equipment from crashing during a brief blackout or brownout and provides you with enough time to shut down everything properly in a more extended power outage.

    For accessories that make cabling easier, just take a look at our many cable management products. We have cable management guides, rackmount raceways, horizontal and vertical organizers, cable managers, cable hangers, and much more. 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...Cabinet accessories.

    Once you’ve chosen your cabinet, whether it be a customized Elite or an energy-saving ClimateCab, it’s time to add accessories for even more function.

    Cabinets have two sets of rails,... more/see it nowfront and back, where you can mount shelves, trays, cable managers, and power strips.

    Shelves
    Shelves are an easy solution for storing things that aren’t rackmountable. The shelves attach to the rails; servers or other equipment sits on the shelves. Make sure the shelf has the weight capacity you need—some can hold hundreds of pounds. For easy access to components in your cabinet, choose a sliding shelf. There are also vented shelves that improve air circulation within the cabinet.

    Although most shelves fit 19" rails, there are shelves that go on the less-common 23" rails. There are also brackets that can adapt many devices intended for 19" mounting to 23" rails.

    Keyboard trays
    Keyboard trays are space-saving solutions that also keep your data center organized. They slide neatly into your cabinet or rack—and out of your way—when not in use. And they usually fit into only 1U of rack space.

    KVM trays
    Further reduce clutter in your server room by using KVM trays that are 1- or 2U high mounted in your cabinet. Special features of Black Box® KVM trays include rock-solid construction, LEDs on the front panel for easy location in a darkened data center, and integrated KVM switching.

    Front-panel controls enable you to use the buttons on a monitor bezel without pulling out the keyboard. Some trays have USB ports for access.

    Cable managers
    Cabinets usually have built-in troughs for cable routing, knockouts for cable pass-throughs, and tie-off points for cable management. You can also add horizontal or vertical cable managers to the cabinet’s rails to manage and route cables more efficiently. Cable managers control bend radius to protect cables from hidden crushes, kinks, and snags, and reduce maintenance time by keeping your cabinet neat and organized. Plus, properly managed cables help to improve airflow.

    SpaceGAIN
    If you’ve got no room to spare in your cabinet, think SpaceGAIN. You might not think of a patch panel as an “accessory,” but SpaceGAIN angled-port and angled patch panels are not your average panels. They free up valuable space and eliminate the need for horizontal cable managers. You save time and money by routing cables directly into ports. And SpaceGAIN high-density feed-through patch panels enable you to fit 48 ports into only 1U of rack space, with no punchdowns needed.

    To save even more space, use SpaceGAIN 90° Right-Angle CAT5e/CAT6 cables. Their up, down, left, or right angles save up to 4" of space in crowded cabinets.

    PDUs and UPSs
    Control the distribution of power in your cabinet with a power distribution unit (PDU). A PDU can be basic or “intelligent,” with surge protection, remote management, or power and environmental monitoring. Integrate a PDU directly into an uninterruptible power supply (UPS) for extra reliability.

    Fans and blowers
    Ventilation in your cabinets is critical for keeping vital equipment cool.

    An enclosure blower draws cool air from a raised floor at the bottom of the cabinet and delivers it right across the front of servers or other network components. It fits on standard 19" rails and uses only 2U of mounting space. This high level of ventilation lowers the temperature of cabinet hot spots by up to 15° F. Lowering temperatures protects your electronics against failure caused by overheating, which may enable you to install more equipment.

    Fan panels or fan trays direct maximum airflow with very little noise to heat-sensitive rackmounted equipment. Position them in your cabinet wherever you need them the most.

    Most network devices take in air through their front panels and expel it out the back. Filler panels in unused rack spaces help keep cool air in the front of the cabinet where it can be used by the equipment.

    Security
    Most cabinets come with a lock and key, but more advanced options are available to provide a higher level of security. Keyless options include combination locks and biometric locks that read fingerprints. 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


    Screw Dimensions

    Find the right screw length for your cabinet or rack.

    Types of Screws

    Screw Dimensions

    There are two basic kinds of screws used for cabinets and racks—panhead screws and countersunk screws—and... more/see it nowthey’re measured in two different ways. Because the standard way to measure is from the tip of the business end of the screw to where the screw rests on the material it’s fastened to, a panhead screw is measured to the bottom of its head, whereas a countersunk screw is measured to the top of its head.
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    Black Box Explains...Cable management.

    Corporate networks are complex systems of PCs, servers, printers, and the devices that connect them. Getting everything to work in harmony requires bundles of cables, and managing all those cables... more/see it nowfrom inside a telecommunications closet can be a daunting task. To connect cable bundles to rackmounted equipment (like patch panels, hubs, switches, or routers), you need to direct the bundles overhead, vertically, and horizontally.

    A popular choice for overhead cable routing is a ladder rack. Ladder racks come in many varieties. They can run along a wall supported by brackets or they can be installed overhead and supported by a threaded rod. Ladder racks can support large cable bundles neatly and safely. Because bundles lie flat on a ladder rack, cables aren’t subjected to harsh bends. You can run ladder racks directly to the top of most standard telecommunications racks that conform to TIA/EIA standards.

    Use vertical cable managers to route cable bundles along the sides of a rack. These “cable troughs” as they’re sometimes called can be single sided—or double sided to route cable bundles to the rear of equipment and to the ports on the front as well. Vertical cable managers usually come with some type of protection for the cable, such as grommeted holes to protect the cable jacket or a cover that may clip on or act as a door.

    Horizontal cable managers are usually a series of rings that directs cables in an orderly fashion toward the ports of hubs, switches, and patch panels. collapse

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