Black Box Explains...USB 2.0 and USB OTG.
The Universal Serial Bus (USB) hardware (plug-and-play) standard makes connecting peripherals to your computer easy.
USB 1.1, introduced in 1995, is the original USB standard. It has two data rates:... more/see it now12 Mbps for devices such as disk drives that need high-speed throughput and 1.5 Mbps for devices such as joysticks that need much lower bandwidth.
In 2002, a newer specification, USB 2.0, or Hi-Speed USB 2.0, gained wide acceptance in the industry. This version is both forward- and backward-compatible with USB 1.1. It increases the speed of the peripheral to PC connection from 12 Mbps to 480 Mbps, or 40 times faster than USB 1.1!
This increase in bandwidth enhances the use of external peripherals that require high throughput, such as CD/DVD burners, scanners, digital cameras, video equipment, and more. USB 2.0 supports demanding applications, such as Web publishing, in which multiple high-speed devices run simultaneously. USB 2.0 also supports Windows® XP through a Windows update.
An even newer USB standard, USB On-The-Go (OTG), is also in development. USB OTG enables devices other than a PC to act as a host. It enables portable equipment—such as PDAs, cell phones, digital cameras, and digital music players—to connect to each other without the need for a PC host.
USB 2.0 specifies three types of connectors: the A connector, the B connector, and the Mini B connector. A fourth type of connector, the Mini A (used for smaller peripherals such as mobile phones), was developed as part of the USB OTG specification. 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...SCSI-1, SCSI-2, SCSI-3, and SCSI-5.
There are standards
and there are standards applied in real-world applications. This Black Box Explains illustrates how SCSI is interpreted by many SCSI manufacturers. Think of these as common SCSI connector... more/see it nowtypes, not as firm SCSI specifications. Notice, for instance, theres a SCSI-5, which isnt listed among the other approved and proposed specifications. However, for advanced SCSI multiport applications, SCSI-5 is often the connector of choice.
Supports transfer rates up to 5 MBps and seven SCSI devices on an 8-bit bus. The most common connector is the Centronics® 50 or a DB50. A Micro Ribbon 50 is also used for internal connections. SCSI-1 equipment, such as controllers, can also have Burndy 60 or 68 connectors.
SCSI-2 introduced optional 16- and 32-bit buses called Wide SCSI. Transfer rate is normally 10 MBps but SCSI-2 can go up to 40 MBps with Wide and Fast SCSI. SCSI-2 usually features a Micro D 50-pin connector with thumbclips. Its also known as Mini 50 or Micro DB50. A Micro Ribbon 60 connector may also be used for internal connections.
Found in many high-end systems, SCSI-3 commonly uses a Micro D 68-pin connector with thumbscrews. Its also known as Mini 68. The most common bus width is 16 bits with transfer rates of 20 MBps.
SCSI-5 is also called a Very High-Density Connector Interface (VHDCI) or 0.8-mm connector. Its similar to the SCSI-3 MD68 connector in that it has 68 pins, but it has a much smaller footprint. SCSI-5 is designed for SCSI-5, next-generation SCSI connections. Manufacturers are integrating this 0.8-mm design into controller cards. Its also the connector of choice for advanced SCSI multiport applications. Up to four channels can be accommodated in one card slot. Connections are easier where space is limited. collapse
Black Box Explains...Multicasting video over a LAN: Use the right switch.
In KVM extension applications where you want to distribute HD video across a network, you need to understand how it works and what kind of networking equipment to use with... more/see it nowyour extenders.
Think of your network as a river of data with a steady current of data moving smoothly down the channel. All your network users are like tiny tributaries branching off this river, taking only as much water (bandwidth) as they need to process data. When you start to multicast video, data, and audio over the LAN, those streams suddenly become the size of the main river. Each user is then basically flooded with data and it becomes difficult or impossible to do any other tasks. This scenario of sending transmissions to every user on the network is called broadcasting, and it slows down the network to a trickle. There are network protocol methods that alleviate this problem, but it depends on the network switch you use.
Unicast vs. multicasting, and why a typical Layer 2 switch isn’t sufficient.
Unicasting is sending data from one network device to another (point to point); in a typical unicast network, Layer 2 switches easily support these types of communications. But multicasting is transmitting data from one network device to multiple users. When multicasting with Layer 2 switches, all attached devices receive the packets, whether they want them or not. Because a multicast header does NOT have a destination IP address, an average network switch (a Layer 2 switch without supported capabilities) will not know what to do with it. So the switch sends the packet out to every network port on all attached devices. When the client or network interface card (NIC) receives the packet, it analyzes it and discards it if not wanted.
The solution: a Layer 3 switch with IGMPv2 or IGMPv3 and packet forwarding.
Multicasting with Layer 3 switches is much more efficient than with Layer 2 switches because it identifies the multicast packet and sends it only to the intended receivers. A Layer 2 switch sends the multicast packets to every device and, If there are many sources, the network will slow down because of all the traffic. And, without IGMPv2 or IGMPv3 snooping support, the switch can handle only a few devices sending multicasting packets.
Layer 3 switches with IGMP support, however, “know” who wants to receive the multicast packet and who doesn’t. When a receiving device wants to tap into a multicasting stream, it responds to the multicast broadcast with an IGMP report, the equivalent of saying, “I want to connect to this stream.” The report is only sent in the first cycle, initializing the connection between the stream and receiving device. If the device was previously connected to the stream, it sends a grafting request for removing the temporary block on the unicast routing table. The switch can then send the multicast packets to newly connected members of the multicast group.
Then, when a device no longer wants to receive the multicast packets, it sends a pruning request to the IGMP-supported switch, which temporarily removes the device from the multicast group and stream.
Therefore, for multicasting, use routers or Layer 3 switches that support the IGMP protocol. Without this support, your network devices will be receiving so many multicasting packets, they will not be able to communicate with other devices using different protocols, such as FTP. Plus, a feature-rich, IGMP-supported Layer 3 switch gives you the bandwidth control needed to send video from multiple sources over a LAN.
Black Box Explains... Standard and ThinNet Ethernet cabling.
The Ethernet standard supports 10-, 100-, and 1000-Mbps speeds. It supports both half- and full-duplex configurations over twisted-pair and fiber cable, as well as half-duplex over coax cable.
However, the Thick... more/see it nowand ThinNet Ethernet standards support only 10-Mbps speeds.
Standard (Thick) Ethernet (10BASE5)
• Uses “Thick” coax cable with N-type connectors for a backbone and a transceiver cable with 15-pin connectors from the transceiver to the network interface card.
• The maximum number of segments is five, but only three can have computers attached. The others are for network extension.
• The maximum length of one segment is 500 meters.
• The maximum total length of all segments is 2500 meters.
• The maximum length of one transceiver cable is 50 meters.
• The minimum distance between transceivers is 2.5 meters.
• No more than 100 transceiver connections per segment are allowed. A repeater counts as a station for both segments.
Thin Ethernet (ThinNet) (10BASE2)
• Uses “Thin” coax cable (RG-58A/U or RG-58C/U).
• The maximum length of one segment is 185 meters.
• The maximum number of segments is five.
• The maximum total length of all segments is 925 meters.
• The minimum distance between T-connectors is 0.5 meters.
• No more than 30 connections per segment are allowed.
• T-connectors must be plugged directly into each device. collapse
Black Box Explains...Cable termination.
Carefully remove the jacketing from the cable and expose one inch of the insulated wire conductors. Do not remove any insulation from the conductors. When the RJ-45 connector is... more/see it nowcrimped, the contacts inside will pierce the conductor insulation.
Untwist the wires to within 1/8" of the jacket. Arrange the wires according to the cable spec (568B in this case). Flatten and align the wires. Make one straight cut across all the conductors, removing approximately 1/2" to ensure the ends are of equal length.
Slide the wires into a connector. The cable jacket should extend into the connector about 1/4" for strain relief. Orient the wires so connector Pin 1 aligns with cable Pin 1, etc. Hold the connector in front of you. With the locking tab down, Pin 1 is on the far left.
Insert the connector into a crimp tool. Make sure you’re using the proper die. Firmly squeeze the handles. They’ll lock in a ratcheting action. A final click indicates the connector is firmly latched.
Check your work using a continuity tester or cable certifier rated for the cable standard you’re installing. Your tester should be able to check for shorts, opens, or miswires.
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...What to look for in a channel solution.
Channel solution. You hear the term a lot these days to describe complete copper or fiber cabling systems. But what exactly is a channel solution and what are its benefits?... more/see it now
A channel solution is a cabling system from the data center to the desktop where every cable, jack, and patch panel is designed to work together and give you consistent end-to-end performance when compared with the EIA/TIA requirements.
A channel solution is beneficial because you have some assurance that your cabling components will perform as specified. Without that assurance, one part may not be doing its job, so your entire system may not be performing up to standard, which is a problem — especially if you rely on bandwidth-heavy links for video and voice.
What to look for.
There are a lot of channel solutions advertised on the Internet and elsewhere. So what exactly should you be looking for?
For one, make sure it’s a fully tested, guaranteed channel solution. The facts show an inferior cabling system can cause up to 70 percent of network downtime — even though it usually represents only 5 percent of an initial network investment. So don’t risk widespread failure by skimping on a system that doesn’t offer guaranteed channel performance. You need to make sure the products are engineered to meet or go beyond the key measurements for CAT5e or CAT6 performance.
And, sure, they may be designed to work together, but does the supplier absolutely guarantee how well they perform as part of a channel — end to end? Don’t just rely on what the supplier says. They may claim their products meet CAT5e or CAT6 requirements, but the proof is in the performance. Start by asking if the channel solution is independently tested and certified by a reputable third party. There are a lot of suppliers out there who don’t have the trademarked ETL approval logo, for example.
What ETL Verified means.
The ETL logo certifies that a channel solution has been found to be in compliance with recognized standards.
To ensure consistent top quality, Black Box participates in independent third-party testing by InterTek Testing Services/ETL Semko, Inc. Once a quarter, an Intertek inspector visits
Black Box and randomly selects cable and cabling products
The GigaTrue® CAT6 and GigaBase® CAT5e Solid Bulk Cable are ETL Verified at the component level to verify that they conform to the applicable industry standards.
The GigaTrue® CAT6 and GigaBase® CAT5e Channels, consisting of bulk cable, patch cable, jacks, patch panels, and wiring blocks, are tested and verified according to industry standards in a LAN environment under InterTek’s Cabling System Channel Verification Program. For the latest test results, contact our FREE Tech Support.
Black Box Explains... Spread Spectrum wireless technology.
Frequency-Hopping Spread Spectrum wireless communication provides error-free transmission, top security, and high levels of throughput without the need for an FCC site license. The key to Spread Spectrum is a... more/see it nowfrequency-hopping transceiver.
Narrow-band frequency hoppers use a predefined algorithm to maintain synchronization and high throughput between master and remote modems. They achieve this by continually switching or “hopping” from one transmission frequency to another throughout the Spread Spectrum band. The sequence of frequencies is very difficult to predict and thus nearly impossible to eavesdrop on or jam. If interference is encountered at any particular frequency, the built-in error correction detects it and resends the data packet at the next frequency hop. Because EMI/RFI interference rarely affects the entire available bandwidth, and each frequency hop is at least 6 MHz, the radio transmitter has access to as many as 100 frequencies within the spectrum to avoid interference and ensure that data gets through. collapse
Black Box Explains...Thermocouples
A thermocouple is a device that measures temperature by using the fact that a junction between two different metals produces a varying voltage related to their temperature. Two common types... more/see it nowof thermocouple are Type J and Type K.
Type J thermocouples use iron paired with a nickel-copper alloy. Type J thermocouples may cover a temperature range of up to -40 to +1382° F (-40 to +750°C), and offer high sensitivity.
Type K, the most common type of thermocouple, uses nickel-chromium and nickel-aluminum alloys. Because Type K is an early specification, its characteristics vary widely; individual thermocouples may cover a range of up to -328 to +2462 °F (-200 to +1350 °C).