Video standards are changing, moving from analog video to digital video. Digital Video Interface, or DVI, was developed by the Digital Display Working Group (DDWG) to replace the VGA connector standard, the "legacy analog technology." [1]

There are some very simple differences between analog and digital video, and simple advantages to switching to digital.

Analog signals travel in a sine-like wave form, and digital signals travel in a square-like waveform. Digital signals offer advantages over analog because the wave shape offers multiple places to read the signal and is more accurate. 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, systems and KVM switches are moving from HD15 or VGA connectors to DVI connectors. The DVI connectors can either support both analog or digital signals depending on the pinning. DVI-I supports both analog and digital signals while DVI-D only supports digital.

Standard resolutions with analog video initially were designed to only 640 x 480 or 800 x 600. They were later stretched to higher resolutions, but 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. 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.

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.

Sources:

[1] http://en.wikipedia.org/wiki/Digital%E2%80%93visual_interface

One of the hottest topics during the past year has been the legal wrangling over counterfeit cable. Last year, Anixter sued Commodity Cables, Inc. The suit alleges that Commodity Cables sold substandard off-shore-manufactured cable that did not meet flame- and fire-resistance standards established by UL® and the National Fire Protection Association. Some of the cable in question was marked as being UL® certified or ETL Verified. Anixter is seeking $1 million in damages plus punitive damages for false advertising, unfair competition, breach of contact, and deceptive trade practices.

The basis of the suit stems from when Anixter said it discovered numerous boxes of cable with apparently fraudulent UL marks. Anixter sent the cables to UL for burn testing, which they failed. In December 2010, Anixter recalled all its Commodity Cables products from customers. Anixter has also worked with many customers to remove and replace the substandard cable.

In June 2011, Commodity Cables countersued Anixter. The counterclaim is a defamation allegation.

More information on the history of the suits can be found at Cabling, Installation & Maintenance. Or, read more about how to avoid unsafe, unapproved, or counterfeit cable.

A common vulnerability in wireless networks is in their ability to create unexpected connections that can result in security gaps. Here are five common wireless security bandits to watch out for:

1.   The rogue access point (AP). A rogue access point is an unauthorized access point connected to your wired network, generally connected by someone in your organization trying to set up do-it-yourself wireless service. Although rogue access points are usually installed innocently enough, they can provide an unsecured gateway right into the heart of your network.

2.   The ad-hoc client. Ad-hoc mode is the ability of wireless devices to connect directly with other wireless devices without accessing an access point. If a computer on your wired network sets up an ad-hoc wireless connection to another computer, that other computer can gain access to your network through the ad-hoc computer.

3.   The out-of-compliance access point. Older access points that have not been updated to the latest firmware release may open your network to hackers. Keeping all the equipment on your network up to date with firmware releases will protect your network from attack to known vulnerabilities. Not doing this can weaken security and reduce network performance. Out-of-compliance access points tend to be a problem in organizations that do not have a security policy that addresses keeping all equipment up to date on their firmware releases.

4. The mis-associated client. This is a problem, not with your wireless network, but with nearby wireless networks. When a wireless client has more than one wireless network to choose from, it may accidentally connect to the wrong network. This kind of mis-association, especially if it’s by a laptop also connected to your wired network, creates a security breach. Although mis-association is usually accidental, a hacker may deliberately create a decoy wireless network that looks like yours in order to fool users into logging on. This connection then allows the hacker to steal passwords and attack your wired network.

5. The non-traditional wireless device. It’s easy to focus on laptop computers and forget about other wireless clients such as personal Bluetooth® devices, cell phones, bar-code readers, and printers that may also use your wireless network. All these devices are vulnerable to cracking and may present an entry to your network to an enterprising hacker.

Your best defense against these common security bandits is a cohesive security strategy that includes network access control, regular site surveys, and a consistent, up-to-date security policy. A centrally managed wireless system makes planning and enforcing network security far more efficient than in “traditional” wireless networks with autonomous access points. Managed systems can often be set to independently handle tasks such as network access control and rogue mitigation, making life far easier for time-stressed IT managers.