Industrial > Modems, CSU/DSUs, Muxes

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 E1 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.

T1 is a digital transmission method for multiplexing multiple voice and data channels over two pairs of wires.

By using a technique called Time-Division Multiplexing (TDM), T1 interleaves both voice and/or LAN data across DS0 subchannels. The primary benefit of T1 is bandwidth—1.544 Mbps—available in 24 easily allocated 64-kbps DS0 subchannels.

T1 sends data in frames made up of 24 eight-bit words (one word for each subchannel) and one framing bit for a total of 193 bits per frame. A T1 channel transmits 8000 frames per second.

The framing bits on successive frames follow a pattern for a superframe format. T1 channel banks check this pattern to make sure synchronization is maintained.

T1 is the most flexible end-to-end digital service option available today. It’s the preferred service for internetworking voice, data, fax, and video signals across an enterprise network. And Black Box is your supplier of T1 hardware with a broad range of solutions for consolidating your global high-speed network management.

Local multiplexors extend the distance between computers and terminals or printers that are connected via customer-installed or telco-supplied cable.

Like line drivers, local multiplexors extend RS-232 communications and must be used in pairs. The difference between the two is that multiplexors merge several transmissions into one transmission over a single channel; line drivers generally transmit data over a single channel.

Local multiplexors operate over ordinary twisted-pair copper cable or fiber optic cable. Copper cable is typically used within buildings while fiber optic cable is the most common choice for connecting buildings in a campus environment. For in-building connections, copper cable is widely used because it’s comparatively inexpensive and easy to install. Your building might even have unshielded twisted-pair cable already in place.

The twisted-pair copper cable used for local multiplexors is run throughout buildings from the wallplates of each office or work area to a central wiring closet within the building. Wiring closets have centrally located punchdown blocks where all cables from the building are terminated. That way, when a connection needs to be changed or a new one needs to be made within the building, wiring can be easily rerouted on the punchdown blocks.

Selecting a local multiplexor.
When selecting a local multiplexor, keep in mind that copper-based multiplexors come in a vast array of types. You’ll find multiplexors available with RJ-11, RJ-45, or terminal block connections for your in-house wiring and with RS-232 connections for your computer equipment. All these multiplexors can be used to link a local device to a remote device within a building.

ISDN stands for Integrated Services Digital Network. It’s a high-speed digital data service provided by most phone companies. With ISDN you can transmit large amounts of data, voice, and video signals up to 128 kbps over a single phone line.

The most common (and least expensive) ISDN service is Basic Rate Interface, or BRI. It’s usually used to combine voice and data circuits over one line between small-scale ISDN sites. BRI consists of two 64-kbps B channels plus a 16-kbps D channel to support system “overhead” functions, such as signaling the telecomm switching system to initiate a call.

What makes ISDN unique is that each B channel is a separate communication circuit. That means just one ISDN line can support simultaneous two-way communication for two devices, such as a computer and a telephone or a computer and a video camera for teleconferencing.

If you need to send more data than one 64-kbps B channel can handle, ISDN also supports BONDing for inverse multiplexing. This links the two B channels into a single logical circuit that can support data rates up to 128 kbps.

ISDN lines are terminated at your location with a special RJ-45 jack. There are two main interfaces. The U interface consists of two wires (one twisted pair) and is common in North America. The S/T interface consists of four unshielded wires (two twisted pairs) and is more common outside North America. Unless you already own U-compatible ISDN phones or PCs, you’ll need a terminal adapter to make the connection.

ISDN is the perfect choice when faster data rates, lower prices, and guaranteed data integrity are required. Consider it for high-volume datacomm applications such as Internet access and on-line service, telecommuting, remote-office routing, and disaster recovery. Also consider ISDN for a high-speed backup line—because you never know when you’ll need one.

DDS (Digital Data Service) is an AT&T® service that transmits data digitally over dedicated leased lines. DDS lines use four wires, and support speeds up to 56 kbps; however, DDS is actually a 64-kbps circuit with 8 kbps being used for signaling. You can also get 64-kbps (ClearChannel™) service. Since the transmission is digital, no modems are needed. Dedicated digital lines are ideal for point-to-point links in wide-area networks.

T1 is a dedicated transmission line operating at 1.544 Mbps. It’s comprised of 24 DSOs, each supporting speeds of 64 kbps. The user sends data at N x 56 or N x 64 over T1 circuits. T1 operates over twisted-pair cable and is suitable for voice, data, and image transmissions on long-distance networks.