Although Ethernet is usually thought of as having a star topology, it’s also possible to build an Ethernet network as a ring. This configuration has the advantage of providing a redundant pathway if a link goes down. A ring topology is often used in application such as traffic signals and surveillance, where long distances may make it difficult to run fiber in a star formation from a central switch and where downtime must be minimized.

The key to the ring topology is spanning tree protocol. One switch-in this case, the switch in the central office-is the root of the spanning tree. A node on the opposite side of the ring blocks on of the ports leading back to the root switch, creating a topology that functions like a long line of Ethernet switches. If a link breaks, the network reorganizes itself to relink all the switches. Although this convergence isn’t instantaneous, it takes only a few seconds to bring the network back. In the diagram below, Hardened Managed Ethernet Switches create a ring topology that operates at Gigabit speed to support traffic cameras at the interaction. Industrial Ethernet Serial Servers make the connection from the switch to the serial interface on the traffic signals, enabling central management of the lights across the Ethernet network.

[Click on image to enlarge]

Hopefully most of you don't rely on Big Lots for your cable. At the end of March 2012, UL issued a public warning about the unauthorized use of the UL® mark on packages of CAT5e and USB patch cable. In the warning, UL states that “The products bear an unauthorized UL Mark on the product packaging. The products have not been evaluated by UL to the applicable Standard for Safety and it is unknown if they comply with the UL safety requirements. ”

The cables listed in the notices are TriQuest 15-foot CAT5e patch cable, model number 60-0102, and TriQuest 10-foot USB 2.0 patch cable, model number 60-0302. The notice reports that the CAT5e cables first went into production in March 2010 and that 124,300 units were produced. The USB cables went into production in February 2010 and 95,120 units were produced. The cables are manufactured by Sela Products, LLC, and they are made in China.

The back of the cable packages is marked with the UL mark in a circle and the words UL Approved. They are not approved, and the use of the UL mark is fraudulent.

You can see photos of the cables and read the notice at the UL Website.

We sat down with Eric Farkas, Senior Research & Development Engineer here at Black Box, and asked him a couple of questions about what kind of media player is needed for digital signage deployments.

There is much confusion in the industry about the kind of “media player” needed for a digital signage deployment. Many screen manufacturers now have PCs embedded into the screen– so is the need for a separate media player less in today’s market?
I think the thing to keep in mind is that it's still a media player either way. You can call it an embedded PC in the display, but it is still a media player. What the screen manufacturers don't necessarily tell you is that built-in media players typically suffer from heat-related issues, have smaller storage capacities, and have less processing power. I think cleaning up the cabling mess by integration does add some value, but losing the freedom to size the hardware resources appropriate to your hardware outweighs it. Also I'm wondering where the guarantee is that this slot will be available on the next generation of displays. If I buy embedded PCs for my signage and a few years from now I need to replace displays due to EoL or I desire to upgrade, can I still use them? External hardware is a pretty definite yes.

Doesn’t the embedded PC act as the media player?
Yes.

And don’t some content management software platforms run on Windows, so they need a full PC/player in each screen, not just a "media player"?

That’s a good question, and frankly, a lot of us suffer from the same confusion as those who ask this question. A media player to me is a PC whether embedded or external, and it has all the same attributes one would associate with a PC. To answer the question, complex digital signage requires an operating system and an application running on PC style hardware. There is technology that simply decodes a network stream or plays a loop from some type of flash storage, but I'm not sure this fits the current definition of digital signage. I guess it begs the question, is a DVD or Blu-ray player digital signage? Is a digital photo frame digital signage? If your answer is yes, then the PC is no longer required but if it's no...

There are now a lot of low-cost, high-definition digital signage media appliances that support third party open source digital signage software as well as offer the ability to input from physical media like Compact Flash. But how does the user tell them apart?
There are many aspects that influence the right digital signage system for your needs, and I feel the most important is your definition or vision of what digital signage is. If you want to show pictures, movies, slideshows, or flash and wish to update the content on-site, a physical media player is probably acceptable. Most physical media players cannot incorporate dynamic content (HTML, RSS, widgets, social media, etc.), interactivity (touchscreen, gesture control, facial recognition, etc.), nor can their content be updated through network-based distribution. In most cases, this also eliminates the integration of emergency management systems and localized content as well.

What about output capability? Is HDMI and/or VGA output needed?
HDMI appears to be the front runner as far as adoption, but it is not without its problems. Compatibility and no method to securely fasten it are the leading issues. VESA has officially announced the end of support for VGA and placed DisplayPort as its successor. I believe the ability to support multiple screens on a single bus will give DisplayPort an edge in the future, but it will struggle to compete with HDMI.

What is the role of the media player in remote playlist updating, scheduling, interactive syncing, and even zoning for digital media and advertising needs?
In the simplest terms, the media player displays the media it is presented with or has cached on the display. However, as digital signage evolves, the need for interactivity and localized playout control/content selection is increasing. Synchronization can be important in some environments, but in most cases, good planning and implementation is a better choice than trying to synchronize content on multiple screens.

How should the systems integrator, or end user, start to separate what is needed–and what’s available–in media players for digital signage?
Ask good questions during the design phase and understand the features of the products you sell intimately. By laying out a matrix of features and price levels, the customer can easily pick the level of signage they desire and can afford. Be sure to focus on the features one level above what they pick and stress their value. If these features are truly unimportant, then the customer probably picked well. If there is hesitation, be sure the features hesitated on can be added later or make it clear that only a forklift upgrade will get them to the next level. Some customers realize the potential of digital signage only after it is implemented and the features outside of the original scope are not available in the solution they deployed.

There’s a lot of excitement nowadays about the Bring Your Own Device (BYOD) trend, in which employees use their own smartphones, tablets, or laptop computers to access the corporate network via wireless. But before you set up those wireless access points, there are a number of questions to consider.

Who’s allowed into the network?

The first step to managing BYOD is to decide who gets on your network. Do you have an open BYOD policy that lets any device connect to your network through wireless? Do you let anyone in, but make him or her register? Do you authenticate users via password? Do you allow only known devices onto the network? Do you support all devices and operating systems?

How much access are BYOD devices allowed?

Do you allow employees’ personal devices full network access or restrict them to Internet access only? If you allow full network access, is there a security policy in place to prevent company confidential information from being loaded into devices that may be lost or stolen?

How safe are BYOD devices and what are you going to do about them?

There’s more malware out there all the time, and it’s affecting more devices than ever. This is a problem not limited to laptop computers—the popular Android™ operating system for phones has a large amount of known malware. How will you screen connecting devices to make sure they have updated patches and don’t contain malware?

What about licensing? 

Do employees want to use corporate software on their personal devices? Do your software licenses have terms that enable you to install the software on machines that are not company owned?

How will you handle roaming?

Can your wireless system handle users who move from access point to access point without dropping sessions or requiring users to log in again? 

For more info, check out our brochure on The Changing Wi-FI Landscape and how to adapt your wireless infrastructure for the BYOD trend.

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 them 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

Or:

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.

Video standards are changing rapidly, from analog to digital. Are you beginning to see more DVI-based monitors in your workplace? What’s the right way to make certain that you’re using this new technology correctly, and getting the greatest advantage from it?

There are some very clear advantages to switching to digital. We can help you make the most of DVI technologies, by providing you with the technical resources to avoid costly pitfalls, and the solutions that enable you to implement DVI to your best advantage.

Digital provides sharper, less vulnerable images
Digital signals are more accurate than analog because the square digital wave shape offers multiple places to read the signal and is more accurate than the sine-like analog signal. Digital signals are also far less vulnerable to EMI and RFI interference, especially when fiber cable is used to transmit the signals.

As a result, all types of systems and KVM switches are moving from HD15 or VGA connectors to DVI connectors. The DVI connectors can support either digital-only or analog-and-digital signals, depending on the pinning. DVI-I supports both analog and digital signals while DVI-D supports digital only.

Digital provides upside for higher resolutions
While it’s true that analog video has been stretched to higher resolutions, the image quality became dependent on many physical factors of the transmission link, and hence more vulnerable to distortion and signal degradation.

Upgrading to digital video brings higher resolutions, usually about 1920 x 1200, at a consistent level of sharpness. Using dual-link video effectively doubles the power of transmission and provides an increase in speed and signal quality. Dual-link video resolutions can display resolutions of 2048 x 1536 or even 2560 x 1600. This resolution is supported on high-definition displays, such as 30″ LCD monitors and digital signage displays.

Digital supports greater distances, too.
DVI-D extenders reach up to 460 feet over CATx cable and up to 40 km over single-mode fiber. These distances will improve as the technology for extending signals improves.

Black Box offers a number of products for digital video extension, including ServSwitch™ DKM switches and extenders the ServSwitch Agility, and the ServSwitch Wizard Dual-Link DVI.

For questions about DVI or making the most of digital video in your KVM environment, talk to a Black Box pre-sales engineer today: 724-746-5500. 

When most people think of counterfeit and substandard cable, they think of bulk cable and their backbone and horizontal runs. But don’t underestimate the importance of patch cables in your channel. Patch cables are the most overlooked component of the Channel Link. Remember the saying, “A chain is only a strong as its weakest link?” The same principle applies to the Channel Link. If a patch cable is non-compliant, it can ruin expensive electronics, invalidate warranties, cause poor network performance, and lead to a loss in productivity. Risky business.

The CCCA did large-scale performance testing of Category 6 copper patch cords. Test results showed an 85% failure rate in cables produced offshore by companies who are largely unknown in North America. 78% of the failing samples failed NEXT tests by a margin of 3 dB or more. A second sample set of Category 6 copper patch cords produced by multiple, well-recognized manufacturers was also tested and showed a 0% failure rate.

Other patch cord issues include non-compliant plugs that don't meet requirements. Problems can include substandard gold plating on the contacts, plating that erodes and corrodes, and contact spacing and dimensional issues that can cause intermittent connections and link loss. If you have poor network performance, the cost to identify the problem and to replace all your patch cables could be quite expensive indeed.

How can you spot substandard patch cable?

Patch cables are usually not supplied by the structured cabling installer but instead they're often purchased by someone in the IT department, who frequently buys them on-line based on price. Just because a cable is advertised as CAT6, it doesn’t mean it’s compliant. Your first tip-off that a cable is substandard is price. If it’s significantly less than what you would expect to pay at Black Box (or any other brand-name manufacturer), it's probably counterfeit. In a recent sampling of patch cable on the Web, we found significant differences in prices. For a 3-foot CAT5e cable, our suspect cable came in at $.85 as compared to $5.45 for our premium GigaBase® cable. For CAT6 cable, we found a 3-foot cable priced at $1.10 as compared to $9.45 for our premium GigaTrue® cable. These low prices are a serious indication the cable is substandard.

Another way to check for inferior cable is to smell it. Some non-compliant cables have a plasticizer issue with the jacketing, which can produce a bad odor. See if the cable feels oily or too stiff. Both are indicators of counterfeit cable. Check the modular plug. It should be intact and not cracked. It should also be made for a fire-resistant plastic. To test this, put a lighter to the clip. If it catches fire and does not self-extinguish, it is substandard. The gold contacts should not be too shiny. Often substandard contacts appear shinier than true gold contacts. Lastly, check the boot to make sure it is not pinching or crushing the cable.

In this day of BYOD—bring your own device—it's challenging to know what kind of devices want access to your local area network (LAN) and how to protect your corporate network from non-corporate assets who should still should be able to access the Internet.

Your organization has a firewall to stop hackers, viruses, and malware at the network's edge. A firewall is vital to safe network operation, but because it operates at the edge of your network, it can only protect you from threats coming from outside your network.

NAC devices, on the other hand, protect your network from threats originating on the inside. Unauthorized devices connected to your network make your organization vulnerable to malware, viruses, and even internal spying and data theft. This is what a NAC device is designed to prevent, whether the vulnerability is a LAN port in a lobby or conference room, or a wireless access point.

In this age of BYOD to work, it's even more difficult for your network to know what devices should be blocked. Most of the time, BYOD users are employees, guests, or contractors who need access to certain network areas, but as non-corporate assets, they should be steered away from others. A NAC that works with your network infrastructure can easily address that concern.

The ideal NAC device helps you do the following:

1. Control who can connect to your network. It detects, alerts, and blocks unauthorized laptops, other network devices, and wireless access points.
2. Protect your network—find and fix vulnerabilities before they're exploited.
3. Detect malware and quarantine infected assets.
4. Comply with requirements for GLBA, HIPAA, HITECH, PCI, ISO 27001, and other security and privacy standards.

To learn more about our NAC solution, visit www.blackbox.com/go/Veri-NAC . You can even enter to win a Veri-NAC 522! See more details here.