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Black Box Explains...Multi-user ServSwitch products vs. multipoint access ServSwitch products.

A multi-user ServSwitch, such as the Matrix ServSwitch, enables two or more users to access different servers at the same time. So, for instance, one user can access “Server A”... more/see it nowwhile another user accesses “Server B.” This is considered a “true two-channel” architecture because two users have independent access to CPUs. It should be pointed out that multiple users cannot access the same server at the same time.

A multipoint access ServSwitch, such as the ServSwitch Duo, provides two access points for control stations but requires that both users view the same server at the same time. So, if one user is accessing “Server A” on his screen, the other user is also seeing “Server A” on his screen. If the second user switches to “Server B,“ the first user will also switch to “Server B.” Only one of these users is actually in control. The user in control stays in control until his workstation is inactive for a period of time (selectable). Then the other station can take control.

A multipoint access ServSwitch is useful when simultaneous, independent access is not required—just the ability to access CPUs from more than one place.

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Black Box Explains…A terminal server by any other name.

A terminal server (sometimes called a serial server or a console server or a device server) is a hardware device that enables you to connect serial devices across a network.

Terminal... more/see it nowservers acquired their name because they were originally used for long-distance connection of dumb terminals to large mainframe systems such as VAX™. Today, the name terminal server refers to a device that connects any serial device to a network, usually Ethernet. In this day of network-ready devices, terminal servers are not as common as they used to be, but they’re still frequently used for applications such as remote connection of PLCs, sensors, or automatic teller machines.

The primary advantage of terminal servers is that they save you the cost of running separate RS-232 devices. By using a network, you can connect serial devices even over very long distances—as far as your network stretches. It’s even possible to connect serial devices across the Internet. A terminal server connects the remote serial device to the network, and then another terminal server somewhere else on the network connects to the other serial device.

Terminal servers act as virtual serial ports by providing the appropriate connectors for serial data and also by grouping serial data in both directions into Ethernet TCP/IP packets. This conversion enables you to connect serial devices across Ethernet without the need for software changes.

Because terminal servers send data across a network, security is a consideration. If your network is isolated, you can get by with an inexpensive terminal server that has few or no security functions. But if you’re using a terminal server to make network connections across a network that’s also an Internet subnet, you should look for a terminal server that offers extensive security features. collapse


USB 3.0

The newest USB standard, USB 3.0 or “SuperSpeed USB," provides vast improvements over USB 2.0. USB 3.0 promises speeds up to 5 Gbps, about ten times that of USB 2.0.... more/see it now

USB 3.0 uses a sync-n-go technology that minimizes user wait time. USB 3.0 adds a physical bus running in parallel with the existing 2.0 bus. It has the flat USB Type A plug, but inside there is an extra set of connectors, and the edge of the plug is blue instead of white. The Type B plug looks different with an extra set of connectors.

USB 3.0 cable contains nine wires, four more than USB 2.0, which has one pair for data and one pair for power. USB 3.0 adds two more data pairs, for a total of eight plus a ground. These extra pairs enable USB 3.0 to support bidirectional asynchronous, full-duplex data transfer instead of USB 2.0’s half-duplex polling method.

USB 3.0 is much more power efficient than USB 2.0. It provides 50% more power than USB 2.0 (150 mA vs 100 mA) to unconfigured devices and up to 80% more power (900 mA vs 500 mA) to configured devices. It is also better at conserving power, when compared to USB 2.0, which uses power when the cable or device isn’t being used. With USB 3.0, when devices are idle, it doesn't broadcast packets or perform polling.

USB 3.0 is completely backwards compatible with USB 2.0. Applications built to the USB 2.0 spec will work seamlessly with USB 3.0. collapse


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


Black Box Explains...Remote power control.

Simply put, remote power control is the ability to reset or reboot PC, LAN, telecom, and other computer equipment without being at the equipment’s location.

Who needs remote power control?... more/see it nowAny organization with a network that reaches remote sites. This can include branch offices, unmanned information kiosks, remote monitoring stations, alarm and control systems, and even HVAC systems.

When equipment locks up at remote sites, it is usually up to the system manager at headquarters to reset it. Often, there aren’t any technically trained personnel at the remote site who can perform maintenance and resets on equipment. So, in order to save traveling time and minimize downtime, remote power control enables the system manager to take care of things at the office without ever leaving home!

Remote power control can be done with modems or existing or special phone lines. The ideal system uses “out-of-band management,“ an alternate path over an ordinary dialup line that doesn’t interfere with network equipment.

An effective remote power control system incorporates the following:
• An existing phone line, such as a line being used for a fax, modem, or phone.
• Transparent operation. The system shouldn’t interfere with or be affected by normal calls.
• Security features. The system should prevent unauthorized access to network equipment.
• Flexibility. System managers should be able to dial in from anywhere and control mulitple devices with one call.
• Have power control devices that meet UL® and FCC requirements. 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.

  • Converters and Scalers Selector
    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...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... Video extenders with built-in skew compensation.

    To ensure the best video resolution, it’s important to match your video extension device with a compatible grade of cable. Some multimedia extenders are not designed to transmit video across... more/see it nowcable that’s higher than CAT5. In fact, with these extenders, the higher-grade cable may actually degrade video.

    The problem is with the cable twists of CAT5e and CAT6 cables. To reduce signaling crosstalk, these higher-grade cables have tighter twists—and more of them—than CAT5 cable does. For this reason, the wire distance that an electrical signal has to travel is different for each pair. This doesn’t normally cause a problem with data, but if you’re sending higher-resolution analog video signals across long cables, you may see color separation caused by the video signals arriving at different times.

    To avoid this, you could use only the lower-grade cable with the extenders. But what if you already have CAT5e or higher cable installed in your building, or you simply want the latest and greatest copper wiring? Order an extender receiver that features built-in skew compensation so it can work properly with higher cable grades at longer distances. collapse


    Black Box Explains...Fiber optic attenuators.

    Attenuators are used with single-mode fiber optic devices and cable to filter the strength of the fiber optic signal. Depending on the type of attenuator attached to the devices at... more/see it noweach end of the fiber optic cable, you can diminish the strength of the light signal a variable amount, measured in decibels (dB).

    Why would you want to filter the strength of the fiber optic signal? Single-mode fiber is designed to carry a fiber optic signal long distances—as much as 70 kilometers (or 43.4 miles). Fiber devices send this signal with great force to ensure that the signal, and your data, arrive at the other end intact.

    But when two fiber devices connected with single-mode fiber cable are close to each other, the signal may be too strong. As a result, the light signal reflects back down the fiber cable. Data can be corrupted and transmissions can be faulty. A signal that is too strong can even damage the attached equipment.

    Because it’s probably not feasible to move your fiber equipment farther apart, the easiest solution is to attach an attenuator to each fiber device. Just as sunglasses filter the strength of sunlight, attenuators filter the strength of the light signal transmitted along single-mode fiber cable. Within the attenuator, there’s doping that reduces the strength of the signal passing through the fiber connection and minute air gaps where the two fibers meet. Fiber grooves may also be intentionally misaligned by several microns—but only enough to slow the fiber optic signal to an acceptable rate as it travels down the cable.

    Before selecting an attenuator, you need to check the type of adapter on your fiber devices. Attenuators typically fit into any patch panel equipped with FC, SC, or LC adapters that contain either PC or APC contacts. In addition to the type of adapter, you also need to determine the necessary attenuation value, such as 5 or 10 dB. This value varies, depending on the strength of fiber optic signal desired. collapse


    Planning a digital signage system.

    How to plan a digital signage project. Considering the many available digital signage solutions might seem like an overwhelming task. But taking some time to research and understand your options will... more/see it nowbe well worth the investment for your institution. Follow these key steps: 1. You need to understand and articulate the objective at the start. Clearly define the goals and determine how you will measure and analyze against the goals. Determine what information you want to communicate and for what purpose. You may want it to give you one or more of the following: • Sales uplift. • Brand messaging. • Entertainment for waiting customers. • Better internal communications. • Public messaging. • Third-party advertising. It is not only imperative to understand what you want the signage to accomplish but also how it will be evaluated. In short, “How will the success or failure of the system be judged and by whom?” What metrics of judgment will be used: ROI, ROO, or other qualifiers? 2. Clearly define the content: The success of any digital signage system starts, of course, with the content. It must look fresh, exciting, and professional. Who will create it and how will it be presented? Do you have internal resources and expertise, or will you need to outsource content creation? A good source of creative and editorial help can be found in aspiring graphic designers culled from the student ranks, in addition to your school’s art department, yearbook and newspaper staffs, and TV studio (if you have one). 3. Invest the time to understand your options: Once you’ve decided on content, you need to consider the infrastructure that will deliver it and study your display options: LCD vs. plasma? RSS feeds? Live video? Remote management? Playback verification? The options will seem limitless, so taking time to sort through them is imperative. 4. Involve all the appropriate stakeholders: The communications/information department should be involved at the start, considering that your digital signage will likely be used for external community relations. If it‘s a K–12 application, you’ll need to include not only your district’s superintendent, principals, purchasing personnel, and IT staff, but also quite possibly instructional technology and AV staff, as well as maintenance, curriculum, athletic, and cafeteria directors. 5. Figure out how you’re going to pay for it: Digital signage is often viewed by some as a luxury item? —? particularly in the face of shrinking school budgets. But because it can also be used as a tool for emergency communications and notification, administrators can easily make the case that digital signage is a must-have component of any crisis plan — especially in this day and age when school violence incidents capture news headlines. Consider government sources of funding for your digital notification system (federal funds are available from the U.S. Department of Homeland Security for pre-disaster mitigation and preparedness, as well as the U.S. Department of Justice, for instance). Whether it’s earmarked entirely as an IT expenditure or apportioned across multiple departments in your budget, you need a spending roadmap in addition to a developmental one. The hardest part with this may be determining the total cost of ownership over the life of the system, including any nickling-and-diming with ongoing licenses and upgrades. College administrators, however, can easily make the case from a cost-savings perspective. Having to constantly update traditional signage across a campus can be quite costly. Paper signage is expensive to print and replace regularly. With digital signage, no printed material is necessary, so both time and cost savings can be made, and the environmental impact is minimized. 6. Decide how to implement the solution: Based on your deployment size and scope, decide if you can implement it in-house or if you need the help of a professional integrator. A number of “out-of-the box” systems can be set up with relative ease. But the more dynamic and complex the system, the more complicated the implementation and ongoing management? — ?and the more likely you’ll need outside help. collapse

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