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Black Box Explains... Manual switch chassis styles.

There are five manual switch chassis styles: three for standalone switches (Styles A, B, and C) and two for rackmount switches (Styles D and E). Below are the specifications for... more/see it noweach style.

Standalone Switches

Chassis Style A
Size — 2.5"H x 6"W x 6.3"D (6.4 x 15.2 x 16 cm
Weight — 1.5 lb. (0.7 kg)
Chassis Style B
Size — 3.5"H x 6"W x 6.3"D (8.9 x 15.2 x 16 cm)
Weight — 1.5 lb. (0.7 kg)
Chassis Style C
Size — 3.5"H x 17"W x 5.9"D (8.9 x 43.2 x 15 cm)
Weight — 8.4 lb. (3.8 kg)

Rackmount Switches

Chassis Style D (Mini Chassis)
Size — 3.5"H x 19"W x 5.9"D (8.9 x 48.3 x 15 cm)
Chassis Style E (Standard Chassis)
Size — 7"H x 19"W x 5.9"D (17.8 x 48.3 x 15 cm) 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.

Typical applications:
• 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...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


Black Box Explains...Low-profile PCI serial adapters.

Ever notice that newer computers are getting smaller and slimmer? That means regular PCI boards won’t 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...Advanced printer switches.

Matrix—A matrix switch is a switch with a keypad for selecting one of many input ports to connect to any one of many output ports.

Port-Contention—A port-contention switch is an... more/see it nowautomatic electronic switch that can be serial or parallel. It has multiple input ports but only one output port. The switch monitors all ports simultaneously. When a port receives data, it prints and all the other ports have to wait.

Scanning—A scanning switch is like a port-contention switch, but it scans ports one at a time to find one that’s sending data.

Code-Operated—Code-operated switches receive a code (data string) from a PC or terminal to select a port.

Matrix Code-Operated—This matrix version of the code-operated switch can be an any-port to any-port switch. This means than any port on the switch can attach to any other port or any two or more ports can make a simultaneous link and transfer data. collapse


Black Box Explains...How fiber is insulated for use in harsh environments.

Fiber optic cable not only gives you immunity to interference and greater signal security, but it’s also constructed to insulate the fiber’s core from the stress associated with use in... more/see it nowharsh environments.

The core is a very delicate channel that’s used to transport data signals from an optical transmitter to an optical receiver. To help reinforce the core, absorb shock, and provide extra protection against cable bends, fiber cable contains a coating of acrylate plastic.

In an environment free from the stress of external forces such as temperature, bends, and splices, fiber optic cable can transmit light pulses with minimal attenuation. And although there will always be some attenuation from external forces and other conditions, there are two methods of cable construction to help isolate the core: loose-tube and tight-buffer construction.

In a loose-tube construction, the fiber core literally floats within a plastic gel-filled sleeve. Surrounded by this protective layer, the core is insulated from temperature extremes, as well as from damaging external forces such as cutting and crushing.

In a tight-core construction, the plastic extrusion method is used to apply a protective coating directly over the fiber coating. This helps the cable withstand even greater crushing forces. But while the tight-buffer design offers greater protection from core breakage, it’s more susceptible to stress from temperature variations. Conversely, while it’s more flexible than loose-tube cable, the tight-buffer design offers less protection from sharp bends or twists. collapse


Black Box Explains...T1 and E1.

If you manage a heavy-traffic data network and demand high bandwidth for high speeds, you need digital super-fast T1 or E1.

Both T1 and E1 are foundations of global communications. Developed... more/see it nowmore than 35 years ago and commercially available since 1983, T1 and E1 go virtually anywhere phone lines go, but they’re much faster. T1, used primarily in the U.S., sends data up to 1.544 Mbps; E1, used primarily in Europe, 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!

T1 and E1 are versatile, too. Drive a private, point-to-point line; provide corporate access to the Internet; enable inbound access to your Web Server—even support a voice/data/fax/video WAN that extends halfway around the world! T1 and E1 are typically used for:
• Accessing public Frame Relay networks or Public Switched Telephone Networks (PSTNs) for voice or fax.
• Merging voice and data traffic. A single T1 or E1 line can support voice and data simultaneously.
• Making super-fast LAN connections. Today’s faster Ethernet speeds require the very high throughput provided by one or more T1 or E1 lines.
• Sending bandwidth-intensive data such as CAD/CAM, MRI, CAT-scan images, and other large files.

Scaling T1
Basic T1 service supplies a bandwidth of 1.536 Mbps. However, many of today’s applications demand much more bandwidth. Or perhaps you only need a portion of the 1.536 Mbps that T1 supplies. One of T1’s best features is that it can be scaled up or down to provide just the right amount of bandwidth for any application.

A T1 channel consists of 24 64-kbps DS0 (Digital Signal [Zero]) subchannels that combine to provide 1.536 Mbps throughput. Because they enable you to combine T1 lines or to use only part of a T1, DS0s make T1 a very flexible standard.

If you don’t need 1.536 Mbps, your T1 service provider can rent you a portion of a T1 line, called Fractional T1. For instance, you can contract for half a T1 line—768 kbps—and get the use of DS0s 1–12. The service provider is then free to sell DS0s 13–24 to another customer.

If you require more than 1.536 Mbps, two or more T1 lines can be combined to provide very-high-speed throughput. The next step up from T1 is T1C; it offers two T1 lines multiplexed together for a total throughput of 3.152 on 48 DS0s. Or consider T2 and get 6.312 Mbps over 96 DS0s by multiplexing four T1 lines together to form one high-speed connection.

Moving up the scale of high-speed T1 services is T3. T3 is 28 T1 lines multiplexed together for a blazing throughput of 44.736 Mbps, consisting of 672 DS0s, each of which supports 64 kbps.

Finally there’s T4. It consists of 4032 64-kbps DS0 subchannels for a whopping 274.176 Mbps of bandwidth—that’s 168 times the size of a single T1 line!

These various levels of T1 service can by implemented simulta-neously within a large enterprise network. Of course, this has the potential to become somewhat overwhelming from a management standpoint. But as long as you keep track of DS0s, you always know exactly how much bandwidth you have at your disposal.

T1’s cousin, E1, can also have multiple lines merged to provide greater throughput. collapse

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