Black Box Explains...Digital Visual Interface (DVI) and other digital display interfaces.
There are three main types of digital video interfaces: P&D, DFP, and DVI. P&D (Plug & Display, also known as EVC), the earliest of these technologies, supports both digital and... more/see it nowanalog RGB connections and is now used primarily on projectors. DFP (Digital Flat-Panel Port) was the first digital-only connector on displays and graphics cards; it’s being phased out.
There are different types of DVI connectors: DVI-D, DVI-I, DVI-A, DFP, and EVC.
DVI-D is a digital-only connector. DVI-I supports both digital and analog RGB connections. Some manufacturers are offering the DVI-I connector type on their products instead of separate analog and digital connectors. DVI-A is used to carry an analog DVI signal to a VGA device, such as a display. DFP, like DVI-D, was an early digital-only connector used on some displays; it’s being phased out. EVC (also known as P&D) is similar to DVI-I only it’s slightly larger in size. It also handles digital and analog connections, and it’s used primarily on projectors.
All these standards are based on transition-minimized differential signaling (TMDS). In a typical single-line digital signal, voltage is raised to a high level and decreased to a low level to create transitions that convey data. TMDS uses a pair of signal wires to minimize the number of transitions needed to transfer data. When one wire goes to a high-voltage state, the other goes to a low-voltage state. This balance increases the data-transfer rate and improves accuracy. collapse
Black Box Explains...Why you should consider a UPS.
Downtime is unacceptable and often costly. But its impossible to get 99.9% uptime when you plug your hardware into an AC outlet.
Power problems are the most common cause of network... more/see it nowinterruptions. According to an IBM® study, the average system is hit by 120 power disturbances per month.
Have you ever had to reset the clock on your VCR or seen the lights dim for a moment when the refrigerator kicks on? These are common occurrences that are insignificant at home but can cause a shutdown in your network. Many power disturbances are so short theyre invisible to the human eye, but they can make a router lock up or a switch require rebooting. Power problems are actually more common than you may know. For instance:
• 34% of network downtime is because of bad power (IBM study).
• 99% of power problems are brownouts (low voltage) or blackouts (complete outages). Only a UPS protects against those.
• It takes 90.87 seconds for switches in non redundant networks to recover from power interruptions.
• 45% of all data loss is caused by power problems.
For a small fraction of the cost of your networking hardware, you can purchase a UPS that protects your network from blackouts, brownouts (low voltages), and surges—even lightning strikes!
To prevent power disasters before they happen, more than 70% of servers are protected with a UPS. Network managers know that having a server down brings many operations to a halt. Although the loss of a single hub or router may not bring the entire corporation to a standstill, it can result in zero productivity for entire workgroups or remote offices.
How can you tell if your system is suffering from power problems?
See if some of these symptoms are familiar: damaged hardware, numerous service calls, erratic operation, unexplained problems, unreliable data, system slowdown, damaged software, system lockups, and more.
If youve experienced some of these problems, you need a UPS. It will keep power flowing, giving you enough time to shut down safely during a power outage. It will also regulate your power, smoothing out dangerous overvoltages and undervoltages, spikes, surges, and impulses that often go unnoticed. These power anomalies can be caused internally by nearby machinery, fluorescent lights, and elevators, as well as externally from nearby transformer problems, lightning strikes, downed power lines, and more.
Data and equipment losses from power problems are preventable. Eliminate system downtime and increase profitability and productivity with a UPS.
When looking for a UPS, consider these steps:
1. List all the equipment you have that needs protection. Remember to include monitors, terminals, hard drives, external modems, and any other equipment in the critical path of potential power or surge sources.
2. Add up the total amperage ratings of your equipment. This information is probably imprinted on the back of each device.
3. Multiply this total amperage figure by the operating voltage (typically 120 VAC in the U.S.) to obtain your total volt/amp (VA) requirement with a safety margin.
4. Select a UPS with a VA capacity at least as high as the amount in Step 3. To accommodate for future expansion, its wise to order a device with an even larger VA rating.
5. If you have questions about which UPS is right for you, contact Tech Support. 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. Its lighter and more flexible than Type 1 Cable and has a better “look.” It’s recommended for use in office environments. collapse
Because Power over Ethernet (PoE) delivers power over the same cable as data, it’s popular for powering devices such as VoIP phones, wireless access points, and security cameras. It often... more/see it nowleads to significant savings by eliminating the need to install a separate power outlet.
Most PoE today is standards-based IEEE 802.3af or the newer higher-powered IEEE 802.3at PoE, which are very safe because power source equipment (PSE) doesn’t add power to the data line unless it detects a compatible powered device (PD) connected to the other end of the cable. This protects devices that do not support PoE. PSEs and PDs also negotiate power requirements, so a PD never receives too much power. Both PSEs and PDs have power supplies and regulators isolated from ground to minimize shock hazard.
But here’s where it gets complicated…
Because most PoE available today is standards-based 802.3af or 802.3at, it’s easy to forget that there are versions of PoE that are NOT standards based. Some of these non-standards-based versions of PoE feature power injectors that inject power without checking compatibility—and that can be very bad news for an innocent network device.
Non-standard PoE tends to fall into three categories: proprietary PoE, high-wattage proprietary PoE, and passive PoE.
Before the ratification of the 802.3af standard in 2003, PoE was a free-for-all with many vendors offering their own method of delivering power over data lines. Some vendors still offer their own proprietary PoE. These proprietary solutions offer varying degrees of communication between PSE and PD. Our Black Box® Wireless Point-to-Point Ethernet Extender Kit (LWE100A-KIT) uses Prorietary PoE in the form of 12 VDC running at 12 W, which is well below the 48 VDC and 15.4 W provided by standard 802.3af.
High-wattage Proprietary PoE.
Many vendors offer high-wattage PoE solutions designed to deliver from 50 watts to 100 or even 200 watts per port. High-wattage proprietary PoE is often used with high-powered outdoor wireless radios.
Passive PoE injects power into an Ethernet cable on Pins 4 and 5 with negative return on Pins 7 and 8 and absolutely no communication between PSE and PD. This method was once a very common “home brew” method of transferring power over data cable and is still commonly used in telecomm applications.
Document and label.
There’s nothing wrong with PoE that’s not standards based—these power methods work as well as 802.3af/at PoE to power network devices. You do, however, need to be aware of what kind of Power over Ethernet you have and what it will work with. Good network documentation and labeling are the keys that enable you to know that, for instance, that power injector is a high-wattage proprietary injector that will fry the IP camera you’re about to connect. Proper documentation, which is good practice in any case, becomes absolutely vital when you have components that may damage other components.
Black Box Explains...Layer 3 switching.
In the last decade, network topologies have typically featured routers along with hubs or switches. The hub or switch acts as a central wiring point for LAN segments while the... more/see it nowrouter takes care of higher-level functions such as protocol translation, traffic between LAN segments, and wide-area access.
Layer 3 switching, which combines Layer 2 switching and Layer 3 IP routing, provides a more cost-effective way of setting up LANs by incorporating switching and routing into one device. While a traditional Layer 2 switch simply sends data along without examining it, a Layer 3 switch incorporates some features of a router in that it examines data packets before sending them on their way. The integration of switching and routing in a Layer 3 switch takes advantage of the speed of a switch and the intelligence of a router in one economical package.
There are two basic types of Layer 3 switching: packet-by-packet Layer 3 (PPL3) and cut-through Layer 3.
PPL3 switches are technically routers in that they examine all packets before forwarding them to their destinations. They achieve top speed by running protocols such as OSPF (Open Shortest Path First) and by using cache routing tables. Because these switches understand and take advantage of network topology, they can blow the doors off traditional routers with speeds of more than 7,000,000 (thats seven million!) packets per second.
Cut-through Layer 3 switching relies on a shortcut for top speed. Cut-through Layer 3 switches, rather than examining every packet, examine only the first in a series to determine its destination. Once the destination is known, the data flow is switched at Layer 2 to achieve high speeds. collapse
Black Box Explains...DIN rail usage.
DIN rail is an industry-standard metal rail, usually installed inside an electrical enclosure, which serves as a mount for small electrical devices specially designed for use with DIN rails. These... more/see it nowdevices snap right onto the rails, sometimes requiring a set screw, and are then wired together.
Many different devices are available for mounting on DIN rails: terminal blocks, interface converters, media converter switches, repeaters, surge protectors, PLCs, fuses, or power supplies, just to name a few.
DIN rails are a space-saving way to accommodate components. And because DIN rail devices are so easy to install, replace, maintain, and inspect, this is an exceptionally convenient system that has become very popular in recent years.
A standard DIN rail is 35 mm wide with raised-lip edges, its dimensions outlined by the Deutsche Institut für Normung, a German standardization body. Rails are generally available in aluminum or steel and may be cut for installation. Depending on the requirements of the mounted components, the rail may need to be grounded. collapse
Black Box Explains...Benefits of T1 and E1.
If you manage a heavy-traffic data network and you demand high bandwidth for high speeds, Black Box has what you need to send your data digitally over super-fast T1 or... more/see it nowE1 communication lines.
Both T1 and E1 are foundations of global voice communication.
Developed more than 30 years ago and commercially available since 1983, T1 and E1 go virtually anywhere phone lines go, but faster.
T1 sends data up to 1.544 Mbps. E1 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!
Both services provide flexibility for a multitude of applications.
Whether you need to drive a private, point-to-point line or a high-speed circuit; provide corporate access to the Internet or inbound access to your own webserver; or support a voice/data/fax/video WAN that extends halfway around the world, T1 or E1 can make the connection.
Both offer cost-effective connections.
In recent years, competition among telco service providers has led to increasingly more affordable prices for T1 and E1 services. In fact, most companies seriously considering a shift to T1 or E1 find they can negotiate even better rates with just a little comparative cost analysis.
• Trunking of V.90 and ISDN remote connection to a central location.
• Accessing public Frame Relay networks for voice, fax, and data.
• Merging voice and data traffic. A single T1 or E1 line can give you several additional voice and data lines at no additional cost.
• Making LAN connections. If you’re linking LANs, a T1 or E1 line offers excellent performance.
• Sending bandwidth-intensive data such as CAD/CAM, MRI, CAT-scan images, and other graphics with large files. collapse
Black Box Explains...Code-operated and matrix switches.
Code-operated and matrix switches from Black Box give you computer-controlled switching for a variety of applications.
BLACK BOX® Code-Operated Switches enable one device to control up to 64 connected devices,... more/see it nowdepending on the code-operated switch. For instance, you can use one modem—not eight—to control eight devices. Code-operated switches are ideal for applications that require remote switching for file sharing or monitoring. Use code-operated switches for:
• Remote programming. Call in via remote sites to access servers, logic controllers, or any devices that require programming.
• Diagnostics. From your master control room, you can probe servers and run diagnostics.
Matrix switches enable more than one device to control other devices. Any port can connect to any port and perform more than one operation at a time independently. The code-operated switches talk to only one slave port at a time.
For instance, if your operation has four computers that need to share two printers and one modem, a matrix switch is what you need to handle the job. Use matrix switches for:
• Industrial applications. You can download instructions remotely to more than one programmable logic controller.
• Data sharing. PCs or industrial devices can be connected—locally or remotely—to other PCs and industrial devices or for file swapping. collapse
Black Box Explains...V.35, the Faster Serial Interface.
V.35 is the ITU (formerly CCITT) standard termed Data Transmission at 48 kbps Using 60108 KHz Group-Band Circuits.
Basically, V.35 is a high-speed serial interface designed to support both higher data... more/see it nowrates and connectivity between DTEs (data-terminal equipment) or DCEs (data-communication equipment) over digital lines.
Recognizable by its blocky, 34-pin connector, V.35 combines the bandwidth of several telephone circuits to provide the high-speed interface between a DTE or DCE and a CSU/DSU (Channel Service Unit/Data Service Unit).
Although its commonly used to support speeds ranging anywhere from 48 to 64 kbps, much higher rates are possible. For instance, maximum V.35 cable distances can theoretically range up to 4000 feet (1200 m) at speeds up to 100 kbps. Actual distances will depend on your equipment and cable.
To achieve such high speeds and great distances, V.35 combines both balanced and unbalanced voltage signals on the same interface. collapse
Black Box Explains...Ceramic and composite ferrules.
Cables manufactured with ceramic ferrules are ideal for mission-critical applications or connections that are changed frequently. These cables are high quality and typically have a very long life. Ceramic ferrules... more/see it noware more precisely molded and fit closer to the fiber than their composite counterparts, which gives them a lower optical loss.
On the other hand, cables with composite ferrules are ideal for less critical applications or connections that won’t be changed frequently. Composite ferrule cables are characterized by low loss, good quality, and long life. collapse