Black Box Explains...Component video.
Traditional Composite video standardsNTSC, PAL, or SECAMcombine luminance (brightness), chrominance (color), blanking pulses, sync pulses, and color burst information into a single signal.
Another video standardS-Videoseparates luminance from chrominance to provide... more/see it nowsome improvement in video quality.
But theres a new kind of video called Component video appearing in many high-end video devices such as TVs and DVD players. Component video is an advanced digital format that separates chrominance, luminance, and synchronization into separate signals. It provides images with higher resolution and better color quality than either traditional Composite video or S-Video. There are two kinds of Component video: Y-Cb-Cr and Y-Pb-Pr. Y-Cb-Cr is often used by high-end DVD players. HDTV decoders typically use the Y-Pb-Pr Component video signal.
Many of todays high-end video devices such as plasma televisions and DVD players actually have three sets of video connectors: Composite, S-Video, and Component. The easiest way to improve picture quality on your high-end TV is to simply connect it using the Component video connectors rather than the Composite or S-Video connectors. Using the Component video connection enables your TV to make use of the full range of video signals provided by your DVD player or cable box, giving you a sharper image and truer colors.
To use the Component video built into your video devices, all you need is the right cable. A Component video cable has three color-coded BNC connections at each end. For best image quality, choose a high-quality cable with adequate shielding and gold-plated connectors. collapse
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...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...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...Upgrading from VGA to DVI video.
Many new PCs no longer have traditional Cathode Ray Tube (CRT) computer monitors with a VGA interface. The latest high-end computers have Digital Flat Panels (DFPs) with a Digital Visual... more/see it nowInterface (DVI). Although most computers still have traditional monitors, the newer DFPs are coming on strong because flat-panel displays are not only slimmer and more attractive on the desktop, but they’re also capable of providing a much sharper, clearer image than a traditional CRT monitor.
The VGA interface was developed to support traditional CRT monitors. The DVI interface, on the other hand, is designed specifically for digital displays and supports the high resolution, the sharper image detail, and the brighter and truer colors achieved with DFPs.
Most flat-panel displays can be connected to a VGA interface, even though using this interface results in inferior video quality. VGA simply cant support the image quality offered by a high-end digital monitor. Sadly, because a VGA connection is possible, many computer users connect their DFPs to VGA and never experience the stunning clarity their flat-panel monitors can provide.
It’s important to remember that for your new DFP display to work at its best, it must be connected to a DVI video interface. You should upgrade the video card in your PC when you buy your new video monitor. Your KVM switches should also support DVI if you plan to use them with DFPs. collapse
Black Box Explains...50-µm vs. 62.5-µm fiber optic cable.
As todays networks expand, the demand for more bandwidth and greater distances increases. Gigabit Ethernet and the emerging 10 Gigabit Ethernet are becoming the applications of choice for current and... more/see it nowfuture networking needs. Thus, there is a renewed interest in 50-micron fiber optic cable.
First used in 1976, 50-micron cable has not experienced the widespread use in North America that 62.5-micron cable has.
To support campus backbones and horizontal runs over 10-Mbps Ethernet, 62.5-micron fiber, introduced in 1986, was and still is the pre-dominant fiber optic cable because it offers high bandwidth and long distance.
One reason 50-micron cable did not gain widespread use was because of the light source. Both 62.5- and 50-micron fiber cable can use either LED or laser light sources. But in the 1980s and 1990s, LED light sources were common. Because 50-micron cable has a smaller aperture, the lower power of the LED light source caused a reduction in the power budget compared to 62.5-micron cablethus, the migration to 62.5-micron cable. At that time, laser light sources were not highly developed and were rarely used with 50-micron cable — and, when they were, it was mostly in research and technological applications.
The cables share many characteristics. Although 50-micron fiber cable features a smaller core (the light-carrying portion of the fiber), both 50- and 62.5-micron cable use the same cladding diameter of 125 microns. Because they have the same outer diameter, theyre equally strong and are handled in the same way. In addition, both types of cable are included in the TIA/EIA 568-B.3 standards for structured cabling and connectivity.
As with 62.5-micron cable, you can use 50-micron fiber in all types of applications: Ethernet, FDDI, 155-Mbps ATM, Token Ring, Fast Ethernet, and Gigabit Ethernet. It is recommended for all premise applications: backbone, horizontal, and intrabuilding connections. And it should be considered especially for any new construction and installations. IT managers looking at the possibility of 10 Gigabit Ethernet and future scalability will get what they need with 50-micron cable. 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... more/see it nowRJ-45 connector is crimped, 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...Modem eliminators.
Understanding the process of elimination.
If your office environment has sync equipment, and if that equipment is also used for local data communications, you should consider replacing those modems with cost-effective... more/see it nowand versatile modem eliminators.
What does a modem eliminator do?
One modem eliminator can connect a local terminal and computer port in lieu of the pair of modems that they would normally connect to. Plus, a modem eliminator enables DCE-to-DTE data and control-signal connections that are not easily achieved by standard cables or connectors in a sync environment.
Basically, a modem eliminator simulates a sync data link. It does this two ways. First, it provides clocking, which is mandatory for sync devices to communicate. Second, it provides the handshaking that DCEs do.
Why should you use a modem eliminator?
One—if you have two sync DTEs in the same room or close to each other, you will need a modem eliminator.
Two—if you have a network with routers, you just found the perfect equipment tester.
A modem eliminator can enable in-house bench testing of routers or existing equipment. Theres no need to place routers all over your network only to find out they don’t work once you test the LAN. A modem eliminator tells you what equipment passes your tests before you install.
Three—a modem eliminator makes good economic sense. One does the job of two modems—and it does the job better. You get a high return on your investment. collapse
Black Box Explains...Low-profile PCI serial adapters.
Ever notice that newer computers are getting smaller and slimmer? That means regular PCI boards wont fit into these computers low-profile PCI slots. But because miniaturization is the rage in... more/see it nowall matters of technology, it was only a short matter of time before low-profile PCI serial adapters became available—and Black Box has them.
Low-profile cards meet the PCI Special Interest Group (PCI-SIG) Low-Profile PCI specifications, the form-factor definitions for input/output expansion. Low-Profile PCI has two card lengths defined for 32-bit bus cards: MD1 and MD2. MD1 is the smaller of the two, with cards no larger than 4.721 inches long and 2.536 inches high. MD2 cards are a maximum of 6.6 inches long and 2.536 inches high.
BLACK BOX® Low-Profile Serial PCI cards comply with the MD1 low-profile specification and are compatible with the universal bus. Universal bus is a PCI card that can operate in either a 5-V or 3.3-V signaling level system. collapse
Black Box Explains...Fiber optic ferrule sleeves.
In a fiber optic adapter, the internal ferrule sleeve holds the fiber in place and aligns the filament of one fiber ferrule with its mate. The ferrule sleeve is the... more/see it nowmost expensive component to manufacture in a fiber optic adapter, accounting for approximately 80% of the total adapter cost.
The ferrule alignment sleeves are also the most critical part of a fiber optic connection process. They provide the bridge between one cables ferrule and another cables ferrule interface. The precision of the ferrule sleeve and its hole determines how well the fibers align, which affects the light signal transmission.
Fiber optic adapters are generally made with ceramic or metal ferrule sleeves. Some adapters also feature ferrule sleeves that are a combination of these materials.
Ceramic ferrule sleeves are more precisely molded and fit close to the fiber ferrule. This precise molding gives the fiber optic connection a lower optical loss. As a general rule, use ceramic ferrule sleeves for critical network connections, such as backbone runs in highly secure networks or for connections that will be changed frequently, like those in wiring closets. Ceramic ferrule sleeves best suit single-mode cable connections.
Ferrule sleeves made of metal, such as bronze ferrules, offer more durability than ceramic sleeves, but they may not offer the same precision alignment as ceramic ferrule sleeves. Drilling an accurate hole through the metal ferrule sleeve can be difficult, and that can result in less accurate fiber alignment. The use of watch-jeweled centering improves alignment. But overall, metal ferrule sleeves are better suited for multimode fiber applications where absolute alignment isnt crucial.