DisplayPort is a digital video interface that was designed by the Video Electronics Standards Association (VESA) in 2006 and has been produced since 2008. It competes directly with HDMI®. Unlike... more/see it nowHDMI, however, DisplayPort is an open standard with no royalties.
This digital interface is used primarily between a computer and a monitor or a high-definition television and is built into many computer chipsets produced today. It’s incredibly versatile, with the capability to deliver digital video, audio, bidirectional communications, and accessory power over a single connector.
DisplayPort v1.1 supports a maximum of 10.8 Gbps over a 2-meter cable; v1.2 supports up to 21.6 Gbps. DisplayPort v1.2 also enables you to daisychain up to four monitors with only a single output cable. It also offers the future promise of DisplayPort Hubs that would operate much like a USB hub.
The standard DisplayPort connector is very compact and features latches that don’t add to the connector’s size. Unlike HDMI, a DisplayPort connector is easily lockable with a pinch-down locking hood, so it can't be easily dislodged. However, a quick squeeze of the connector releases the latch.
DisplayPort supports cable lengths of up to 15 meters with maximum resolutions at cable lengths up to 3 meters. Bidirectional signaling enables DisplayPort to both send and receive data from an attached device.
With the proper adapters, DisplayPort cable can carry DVI and HDMI signals, although this doesn’t work the other way around—DVI and HDMI cable can’t carry DisplayPort. Because DisplayPort can provide power to attached devices, DisplayPort to HDMI or DVI adapters don’t need a separate power supply.
The Mini DisplayPort (MiniDP or mDP) is a miniatured version of the DisplayPort interface. It carries both digital and analog computer video and audio signals. Apple® introduced the Mini DisplayPort connector in 2008 and it is now on all new Mac® computers. It is also being used in newer PC notebooks. This small form factor connector fully supports the VESA DisplayPort protocol. It is particularly useful on systems where space is at a premium, such as laptops, or to support multiple connectors on reduced height add-in cards.
Black Box Explains…HDMI
The High-Definition Multimedia Interface (HDMI®) is the first digital interface to combine uncompressed high-definition video, up to eight channels of uncompressed digital audio, and intelligent format and command data in... more/see it nowa single cable. It is now the de facto standard for consumer electronics and high-definition video and is gaining ground in the PC world.
HDMI supports standard, enhanced, and high-definition video. It can carry video signals at resolutions up to and beyond 1080p at 60 Hz (Full HD). The latest version eve support 4K video resolutions.
HDMI offers an easy, standardized way to set up home theaters and AV equipment over one cable. Use it to connect audio/video equipment, such as DVD players, set-top boxes, and A/V receivers with an audio and/or video equipment, such as a digital TVs, PCs, cameras, and camcorders. It also supports multiple audio formats from standard stereo to multichannel surround sound. Plus it provides two-way communications between the video source and the digital TV, enabling simple remote, point-and-click configurations.
NOTE: HDMI also supports HDCP (High-bandwidth Digital Content Protection), which prevents the copying of digital audio and video content transmitted over HDMI able. If you have a device between the source and the display that supports HDMI but not HDCP, your transmission won't work, even over an HDMI cable.
HDMI offers significant benefits over older analog A/V connections. It's backward compatible with DVI equipment, such as PCs. TVs, and other electronic devices using the DVI standard. A DVI-to-HDMI adapter can be used without a loss of video quality. Because DVI only supports video signals, no audio, the DVI device simply ignores the extra audio data.
The HDMI standard was introduced in December 2002. Since then, there have been a number of versions with increasing bandwidth and/or transmission capabilities.
With the introduction of HDMI (June 2006), more than doubled the bandwidth from 4.95 Gbps to 10.2 Gbps (340 MHz). It offers support for 16-bit color, increased refresh rates, and added support for 1440p WQXGA. It also added support for xvYCC color space and Dolby True HD and DTS-HD Master Audio standards. Plus it added features to automatically correct audio video synchronization. Finally, it added a mini connector.
HDMI 1.3a (November 2006), HDMI 1.3b (March 2007, HDMI 1.3b1 (November 2007), and 1.3c (August 2008) added termination recommendations, control commands, and other specification for testing, etc.
HDMI 1.4 (May 2009) increased the maximum resolution to 4Kx 2K (3840 x 2160 p/24/25/30 Hz). It added an HDMI Ethernet channel for a 100-Mbps connection between two HDMI devices. Other advancements include: an Audio Return Channel, stereoscopic 3D over HDMI (HDMI 1.3 devices will only support this for 1080i), an automotive connection system, and the micro HDMI connector.
HDMI 1.4a (March 2010) adds two additional 3D formats for broadcast content.
HDMI 2.0 (August 2013), which is backwards compatible with earlier versions of the HDMI specification, significantly increases bandwidth up to 18 Gbps and adds key enhancements to support market requirements for enhancing the consumer video and audio experience.
HDMI 2.0 also includes the following advanced features:
Resolutions up to 4K@50/60 (2160p), which is four times the clarity of 1080p/60 video resolution, for the ultimate video experience.
Up to 32 audio channels for a multi-dimensional immersive audio experience.
Up to 1536Hz audio sample frequency for the highest audio fidelity.
Simultaneous delivery of dual video streams to multiple users on the same screen.
Simultaneous delivery of multi-stream audio to multiple users (up to four).
Support for the wide angle theatrical 21:9 video aspect ratio.
Dynamic synchronization of video and audio streams.
CEC extensions provide more expanded command and control of consumer electronics devices through a single control point.
There are four HDMI connector types. Type A and Type B are defined in the HDMI 1.0 specification. Type C is defined in HDMI 1.3, and Type D is defined in HDMI 1.4.
Type A: 19 pins. It supports all SDTV, EDTV, and HDTV modes. It is electrically compatible with single-link DVI-D.
Type B: 29 pins. Offers double the video bandwidth of Type A. Use for very high-resolution displays such as WQUXGA. It's electronically compatible with dual-link DVI-D.
Type C Mini: 19 pins. This mini connector is intended for portable devices. It is smaller than Type A but has the same pin configuration and can be connected to Type A cable via an adapter or adapter cable.
Type D Micro: 19 pins. This also has the 19-pin configuration of Type A but is about the size of a micro-USB connector.
Recently, HDMI Licnsing, LLC announced that all able would be tested as either Standard or High-Speed cables. Referring to cables based on HDMI standard (e.g. 1.2, 1.3 etc.) is no longer allowed.
Standard HDMI cable is designed for use with digital broadcast TV, cable TV, satellites TV, Blu-ray, and upscale DVD payers to reliably transmit up to 1080i or 720p video (or the equivalent of 75 MHz or up to 2.25 Gbps).
High-Speed HDMI reliably transmits video resolutions of 1080p and beyond, including advanced display technologies such as 4K, 3D, and Deep Color. High-Speed HDMI is the recommended cable for 1080p video. It will perform at speeds of 600 MHz or up to 18 Gbps, the highest bandwidth urgently available over an HDMI cable.
Additional resources and licensing information is available at HDMI.org. collapse
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.
Black Box Explains...Multimode vs. single-mode Fiber.
Multimode, 50- and 62.5-micron cable.
Multimode cable has a large-diameter core and multiple pathways of light. It comes in two core sizes: 50-micron and 62.5-micron.
Multimode fiber optic cable can be... more/see it nowused for most general data and voice fiber applications, such as bringing fiber to the desktop, adding segments to an existing network, and in smaller applications such as alarm systems. Both 50- and 62.5-micron cable feature the same cladding diameter of 125 microns, but 50-micron fiber cable features a smaller core (the light-carrying portion of the fiber).
Although both can be used in the same way, 50-micron cable is recommended for premise applications (backbone, horizontal, and intrabuilding connections) and should be considered for any new construction and installations. Both also use either LED or laser light sources. The big difference between the two is that 50-micron cable provides longer link lengths and/or higher speeds, particularly in the 850-nm wavelength.
Single-mode, 8–10-micron cable.
Single-mode cable has a small, 8–10-micron glass core and only one pathway of light. With only a single wavelength of light passing through its core, single-mode cable realigns the light toward the center of the core instead of simply bouncing it off the edge of the core as multimode does.
Single-mode cable provides 50 times more distance than multimode cable. Consequently, single-mode cable is typically used in long-haul network connections spread out over extended areas, including cable television and campus backbone applications. Telcos use it for connections between switching offices. Single-mode cable also provides higher bandwidth, so you can use a pair of single-mode fiber strands full-duplex for up to twice the throughput of multimode fiber.
50-/125-Micron Multimode Fiber
Bandwidth: 500 MHz/km;
Attenuation: 3.5 dB/km;
Distance: 550 m;
Bandwidth: 500 MHz/km;
Attenuation: 1.5 dB/km;
Distance: 550 m
62.5-/125-Miron Multimode Fiber
Bandwidth: 160 MHz/km;
Attenuation: 3.5 dB/km;
Distance: 220 m;
Bandwidth: 500 MHz/km;
Attenuation: 1.5 dB/km;
Distance: 500 m
8–10-Micron Single-Mode Fiber
Wavelength: 1310 nm and 1550 nm;
Attenuation: 1.0 dB/km;
Outside Plant Application:
Wavelength: 1310 nm and 1550 nm;
Attenuation: 0.1 dB/km collapse
Black Box Explains…TEMPEST.
TEMPEST is an acronym for Telecommunications Electronics Material Protected from Emanating Spurious Transmissions. It pertains to technical security countermeasures, standards, and instrumentation that prevent or minimize the exploitation of vulnerable... more/see it nowdata communication equipment by technical surveillance or eavesdropping.
What puts your data communication equipment at risk?
Many things. But first and foremost, its microchip.
Any device with a microchip generates an electromagnetic field, often called a “compromising emanation” by security experts. With the proper surveillance equipment, these emanations can be intercepted and the signal reconstructed and analyzed. Unprotected equipment can, in fact, emit a signal into the air like a radio station—and nobody wants to risk his or her job and a whole lot more by broadcasting national security or trade secrets to the wrong people.
Some of the most vulnerable devices are speakerphones, printers, fax machines, scanners, external disc drives, and other high-speed, high-bandwidth peripherals. If the snoop is using a high-quality interception device, your equipment’s signals can be acquired up to several hundred feet away.
Arguably one of the most vulnerable pieces of equipment is an analog VGA monitor. If a spy were to introduce a Trojan into your system, he or she could monitor and store key presses and passwords used during the day. When the system’s not in use at night, the spy could pulse the VGA screen with grayscale images that have a strong signal at particular frequencies. VGA uses single-ended signaling that has a high common-mode emission level not protected by cable shielding, and it’s possible to monitor these signals outside the secure zone using a radio receiver. Even without a Trojan, a sophisticated receiver located nearby picks up and views what’s on the VGA monitor.
What TEMPEST is and isn’t.
It should come as no surprise that the Federal government became concerned about signal leakage. In fact, its interest goes back to the days of World War I when the Army was trying to exploit weaknesses of enemy combat phones and radio transmitters. Since then, the scope of the government’s interests has broadened beyond battlefield equipment. In the last
40 years, the National Security Agency (NSA) has taken several industry measurement standards and greatly beefed them up. These enhanced criteria are commonly referred to as the TEMPEST standards (although the NSA also calls them EMSEC standards, short for “emissions security”).
TEMPEST disciplines involve designing circuits to minimize emanations and the application of appropriate shielding, grounding, and bonding. Some methods used include radiation screening, alarms, and isolation.
A TEMPEST-approved device resembles its non-secure version with a few key differences. If it’s a network component such as a switch, it comes in a heavy metal case. It also has special shielding, a modified power supply, and perhaps a few other modifications from the standard model. If you need to open the device’s case,
a special torque wrench for use with TEMPEST-only products is required.
TEMPEST test equipment is very expensive and is sold exclusively to government agencies. Nobody can sell you commercial TEMPEST testing equipment. And if someone offers you a “TEMPEST surveillance system,” you need to be aware of two things: First, TEMPEST is counter-surveillance science and the offer is a fraud; second, the salesperson is committing a federal felony.
If you buy surveillance equipment—authentic or not—then you have also commited a felony. Construction of, possession of, attempting a sale of, or attempting a purchase of said surveillance equipment is illegal. Even if the product purchased is a hoax, the law will take your intentions into account as much as the salesperson’s. Don’t be surprised if you
both go to jail.
In the United States, you can learn about TEMPEST testing only in special schools sanctioned by, if not run by, the NSA. Courses to earn the TEMPEST Technician or TEMPEST Engineer certifications are very expensive. These classes are offered to a limited number of people who have a very high level of security clearance and who will be working on TEMPEST-approved equipment all the time.
All TEMPEST-approved communication devices have a rating based on their application and/or environment.
Type 1: This rating is for classified cryptographic equipment used for national security purposes. It’s endorsed by the NSA for securing telecommunications and automated information systems and for the protection of classified or sensitive U.S. Government information.
Type 2: This rating is for unclassified cryptographic equipment used by U.S. Government agencies, state and local governments, and sponsored U.S. Government contractors. It’s endorsed by the NSA for securing telecommunications and automated information systems and for the protection of unclassified but sensitive information, such as contract bids.
Type 3: This rating is for unclassified commercial cryptographic equipment that implements an algorithm registered with the National Institute of Standards and Technology (NIST). It’s for use in protecting sensitive information, like a corporation’s network communications. collapse
Black Box Explains...Power problems.
The Threat — A sag is a decline in the voltage level. Also known as “brownouts,” sags are the most common power problem.
The Cause — Sags can be caused... more/see it nowlocally by the start-up demands of electrical devices such as motors, compressors, and elevators. Sags may also happen during periods of high electrical use, such as during a heat wave.
The Effect — Sags are often the cause of “unexplained” computer glitches such as system crashes, frozen keyboards, and data loss. Sags can also reduce the efficiency and lifespan of electrical motors.
The Threat — A blackout is a total loss of power.
The Cause — Blackouts are caused by excessive demand on the power grid, an act of nature such as lightning or an earthquake, or a human accident such as a car hitting a power pole or a backhoe digging in the wrong place.
The Effect — Of course a blackout brings everything to a complete stop. You also lose any unsaved data stored in RAM and may even lose the total contents of your hard drive.
The Threat — A spike, also called an impulse, is an instantaneous, dramatic increase in voltage.
The Cause — A spike is usually caused by a nearby lightning strike but may also occur when power is restored after a blackout.
The Effect — A spike can damage or completely destroy electrical components and also cause data loss.
The Threat — A surge is an increase in voltage lasting at least 1/120 of a second.
The Cause — When high-powered equipment such as an air conditioner is powered off, the excess voltage is dissipated though the power line causing a surge.
The Effect — Surges stress delicate electronic components causing them to wear out before their time.
The Threat — Electrical noise, more technically called electromagnetic interference (EMI) and radio frequency interference (RFI), interrupts the smooth sine wave expected from electrical power.
The Cause — Noise has many causes including nearby lightning, load switching, industrial equipment, and radio transmitters. It may be intermittent or chronic.
The Effect — Noise introduces errors into programs and data files. collapse
Black Box Explains...10-GbE, CAT6A, and ANEXT.
The IEEE released the 802.3an 10GBASE-T standard in June 2006. This standard specifies 10-Gbps data transmission
over four-pair copper cabling. 10-Gigabit Ethernet (10-GbE) transmission includes up to 37 meters of... more/see it nowCAT6 cable (with installation mitigation techniques), 100 meters of Augmented Category 6 (CAT6A) UTP or F/UTP cable or 100 meters
of S/FTP CAT7/Class F cable.
CAT6A is the ANSI/TIA 10-Gigabit Ethernet (10-GbE) over copper standard. Its requirements are covered in ANSI/TIA-568-C.2 (Balanced Twisted-Pair Communications Cabling and Components Standard) published in August 2009. It defines 10-Gigabit data transmission over a 4-connector twisted-pair CAT6A copper cable for a distance of 100 meters.
Category 6A cabling is designed to support next-generation applications, including the transfer of large amounts of data at high speeds, up to 10 Gbps. CAT6A extends electrical specifications to 500 MHz from 250 MHz for CAT6 cabling. CAT6A cables are fully backward compatible with previous categories, including CAT6 and 5e. Category 6A is also designed to support bundled cable installations up to 100 meters and PoE+ low-power implementations. The standard includes the performance parameter, Alien Crosstalk (ANEXT). Because of its higher performance transmission speeds and higher MHz rating, CAT6A cable needs to be tested for external noise outside the cable, which wasn’t a concern with previous cabling categories. CAT6A UTP also has a much larger diameter than previous cables.
Alien crosstalk (ANEXT) is a critical and unique measurement in 10-GbE systems. Crosstalk, measured in 10/100/1000BASE-T systems, is the mixing of signals between wire pairs within a cable. Alien Crosstalk, in 10-GbE systems, is the measurement of the unwanted signal coupling between wire pairs in different and adjacent cables or from one balanced twisted-pair component, channel, or permanent link to another.
The amount of ANEXT depends on a number of factors, including the type of cable, cable jacket, cable length, cable twist density, proximity of adjacent cables, and connectors, and EMI. Patch panels and connecting hardware are also affected by ANEXT.
With Alien Crosstalk, the affected cable is called the victim cable. The surrounding cables are the disturber cables.
There are a number of ways to mitigate the effects of ANEXT in CAT6A runs. According to the standards, ANEXT can be improved by laying CAT6A UTP cable loosely in pathways and raceways with space between the cables. This contrasts to the tightly bundled runs of CAT6/5e cable that we are used to. The tight bundles present a worst-case scenario of six cables around one, thus the center cable would be adversely affected by ANEXT. CAT6A UTP cable needs to be tested for ANEXT. This is a complex and time-consuming process in which all possible wire-pair combinations need to be tested for ANEXT and far-end ANEXT. It can take 50 minutes to test one link in a bundle of 24 CAT 6A UTP cables.
To virtually eliminate the problem of ANEXT, you can use CAT6A F/UTP cable. The F indicates an outer foil shield encasing four unshielded twisted pairs. This cable is also a good choice when security is an issue because it doesn’t emit signals. In addition, CAT6A F/UTP cable works well in noisy environments with a lot of EMI/RFI.
Installation of CAT6A F/UTP is simpler, too, because the cable features a smaller outside diameter than CAT6A UTP. Its construction makes it easier to pull and more resilient. The cable also has a smaller diameter so you can run more cables in a conduit or pathway, and have greater patch panel port density.
For more information, see the CAT6A F/UTP vs. UTP: What You Need to Know white paper in the Resources section at blackbox.com.
Black Box Explains...Category wiring standards
The ABCs of standards
There are two primary organizations dedicated to developing and setting structured cabling standards. In North America, standards are issued by the Telecommunications Industry Association (TIA),... more/see it nowwhich is accredited by the American National Standards Institute (ANSI). The TIA was formed in April 1988 after a merger with the Electronics Industry Association (EIA). That’s why its standards are commonly known as ANSI/TIA/EIA, TIA/EIA, or TIA.
Globally, the organizations that issue standards are the International Electrotechnical Commission (IEC) and the International Organization for Standardization (ISO). Standards are often listed as ISO/IEC. Other organizations include the Canadian Standards Association (CSA), CENELEC (European Committee for Electrotechnical Standardizations), and the Japanese Standards Association (JSA/JSI).
The committees of all these organizations work together and the performance requirements of the standards are very similar. But there is some confusion in terminology.
The TIA cabling components (cables, connecting hardware, and patch cords) are labeled with a ”category.” These components together form a permanent link or channel that is also called a ”category.” The ISO/IEC defines the link and channel requirements with a ”class” designation. But the components are called a ”category.”
Category 5 (CAT5) —ratified in 1991. It is no longer recognized for use in networking.
Category 5e (CAT5e), ISO/IEC 11801 Class D, ratified in 1999, is designed to support full-duplex, 4-pair transmission in 100-MHz applications. The CAT5e standard introduced the measurement for PS-NEXT, EL-FEXT, and PS-ELFEXT. CAT5e is no longer recognized for new installations. It is commonly used for 1-GbE installations.
Category 6 (CAT6) – Class E has a specified frequency of 250 MHz, significantly improved bandwidth capacity over CAT5e, and easily handles Gigabit Ethernet transmissions. CAT6 supports 1000BASE-T and, depending on the installation, 10GBASE-T (10-GbE).
10-GbE over CAT6 introduces Alien Crosstalk (ANEXT), the unwanted coupling of signals between adjacent pairs and cables. Because ANEXT in CAT6 10-GbE networks is so dependent on installation practices, TIA TSB-155-A and ISO/IEC 24750 qualifies 10-GbE over CAT6 over channels of 121 to 180 feet (37 to 55 meters) and requires it to be 100% tested, which is extremely time consuming. To mitigate ANEXT in CAT6, it is recommended that the cables be unbundled, that the space between cables be increased, and that non-adjacent patch panel ports be used. If CAT6 F/UTP cable is used, mitigation is not necessary and the length limits do not apply. CAT6 is not recommended for new 10-GbE installations.
Augmented Category 6 (CAT6A) –Class Ea was ratified in February 2008. This standard calls for 10-Gigabit Ethernet data transmission over a 4-pair copper cabling system up to 100 meters. CAT6A extends CAT6 electrical specifications from 250 MHz to 500 MHz. It introduces the ANEXT requirement. It also replaces the term Equal Level Far-End Crosstalk (ELFEXT) with Attenuation to Crosstalk Ratio, Far-End (ACRF) to mesh with ISO terminology. CAT6A provides improved insertion loss over CAT6. It is a good choice for noisy environments with lots of EMI. CAT6A is also well-suited for use with PoE+.
CAT6A UTP cable is significantly larger than CAT6 cable. It features larger conductors, usually 22 AWG, and is designed with more space between the pairs to minimize ANEXT. The outside diameter of CAT6A cable averages 0.29"–0.35" compared to 0.21"–0.24" for CAT6 cable. This reduces the number of cables you can fit in a conduit. At a 40% fill ratio, you can run three CAT6A cables in a 3/4" conduit vs. five CAT6 cables.
CAT6A UTP vs. F/UTP. Although shielded cable has the reputation of being bigger, bulkier, and more difficult to handle and install than unshielded cable, this is not the case with CAT6A F/UTP cable. It is actually easier to handle, requires less space to maintain proper bend radius, and uses smaller conduits, cable trays, and pathways. CAT6A UTP has a larger outside diameter than CAT6A F/UTP cable. This creates a great difference in the fill rate of cabling pathways. An increase in the outside diameter of 0.1", from 0.25" to 0.35" for example, represents a 21% increase in fill volume. In general, CAT6A F/UTP provides a minimum of 35% more fill capacity than CAT6A UTP. In addition, innovations in connector technology have made terminating CAT6A F/UTP actually easier than terminating bulkier CAT6A UTP.
Category 7 (CAT7) –Class F was published in 2002 by the ISO/IEC. It is not a TIA recognized standard and TIA plans to skip over it.
Category 7 specifies minimum performance standards for fully shielded cable (individually shielded pairs surrounded by an overall shield) transmitting data at rates up to 600 MHz. It comes with one of two connector styles: the standard RJ plug and a non-RJ-style plug and socket interface specified in IEC 61076-2-104:2.
Category 7a (CAT7a) –Class Fa (Amendment 1 and 2 to ISO/IEC 11801, 2nd Ed.) is a fully shielded cable that extends frequency from 600 MHz to 1000 MHz.
Category 8 – The TIA decided to skip Category 7 and 7A and go to Category 8. The TR-42.7 subcommittee is establishing specs for a 40-Gbps twisted-pair solution with a 2-GHz frequency. The proposed standard is for use in a two-point channel in a data center at 30 meters. It is expected to be ratified in February 2016. The TR-42.7 subcommittee is also incorporating ISO/IEC Class II cabling performance criteria into the standard. It is expected to be called TIA-568-C.2-1. The difference between Class I and Class II is that Class II allows for three different styles of connectors that are not compatible with one another or with the RJ-45 connector. Class I uses an RJ-45 connector and is backward compatible with components up to Category 6A.
Black Box Explains...Why media converters need SNMP.
The number of Ethernet switches and fiber optic segments being added to Ethernet networks keeps increasing. And as long as most Ethernet switches are only available with 10BASE-T and 100BASE-TX... more/see it nowinterfaces, media converters will remain in demand.
Until now, a failure on the network could go unnoticed. Once a failure was detected, it could take a long time to isolate it, especially if a technician had to be sent to the site. But media converters with SNMP eliminate some of the guesswork.
With SNMP, the IS manager can detect a failure, isolate it to a specific port, and determine what hardware is required to repair it. A technician can then be sent directly to the right place to fix faulty hardware or repair a broken cable.
SNMP enables you to set up alarms or traps when a link is down. You can turn features on and off from a central terminal, so theres no need to leave your desk. You can also monitor power supplies and replace them without interrupting service. SNMP management reduces the time and money it takes to get your network up and running again. The users on your network will notice—and appreciate—the improved service and reliability. collapse
Black Box Explains...UARTs and PCI buses.
Universal Asynchronous Receiver/Transmitters UARTs are designed to convert sync data from a PC bus to an async format that external I/O devices such as printers or modems use. UARTs insert... more/see it nowor remove start bits, stop bits, and parity bits in the data stream as needed by the attached PC or peripheral. They can provide maximum throughput to your high-performance peripherals without slowing down your CPU.
In the early years of PCs and single-application operating systems, UARTs interfaced directly between the CPU bus and external RS-232 I/O devices. Early UARTs did not contain any type of buffer because PCs only performed one task at a time and both PCs and peripherals were slow.
With the advent of faster PCs, higher-speed modems, and multitasking operating systems, buffering (RAM or memory) was added so that UARTs could handle more data. The first buffered UART was the 16550 UART, which incorporates a 16-byte FIFO (First In First Out) buffer and can support sustained data-transfer rates up to 115.2 kbps.
The 16650 UART features a 32-byte FIFO and can handle sustained baud rates of 460.8 kbps. Burst data rates of up to 921.6 kbps have even been achieved in laboratory tests.
The 16750 UART has a 64-byte FIFO. It also features sustained baud rates of 460.8 kbps but delivers better performance because of its larger buffer.
Used in newer PCI cards, the 16850 UART has a 128-byte FIFO buffer for each port. It features sustained baud rates of 460.8 kbps.
The Peripheral Component Interconnect (PCI®) Bus enhances both speed and throughput. PCI Local Bus is a high-performance bus that provides a processor-independent data path between the CPU and high-speed peripherals. PCI is a robust interconnect interface designed specifically to accommodate multiple high-performance peripherals for graphics, full-motion video, SCSI, and LANs.
A Universal PCI (uPCI) card has connectors that work with both a newer 3.3-V power supply and motherboard and with older 5.5-V versions. collapse