Glossary

2B+D

The Basic Rate Interface (BRI) in ISDN. A single ISDN circuit divided into two 64 kbps digital channels for voice or data and one 16 kbps channel for low speed data (up to 9,600 baud) and signalling. 2B+D is carried on one or two pairs of wires depending on the interface, the same wire pairs that today bring a single voice circuit int

o your home or office. See ISDN.

23B+D

In ISDN, also known as the Primary Rate Interface. A circuit with a wide range of frequencies that is divided in twenty-three 64 kbps paths for carrying voice, data, video, or other information simultaneously. It bears a remarkable similarity to today's T1 link, except that T1 carries 24 voice channels. In ISDN, 23B+D gives twenty-three channels and one D channel for out of band signalling. However, in T1, signalling is

handled in band. See ISDN.

two-wire circuit

A transmission circuit composed of two wires, signal and ground, used to both send and receive information. In contrast, a 4-wire circuit consists of two pairs. One pair is used to send. One pair is used to receive. All trunk circuits (long distance) are

4-wire. A 4-wire circuit delivers better reception, but also costs more. All local loop circuits (those coming from a Class 5 central office to the subscriber's phone system) are 2-wire, unless a 4-wire circuit is requested.

U-interface

A twisted pair subscriber loop that connects the NT1 reference point to the ISDN network, as defined in the I.411 Recommendation. This interface provides Basic Rate Access with an operating frequency of 160 kbps and an information rate of 144 kbps. Under U.S. regulations, this also marks the line of demarcation between customer- owned equipment and the public network.

video-conferencing

The real-time, usually two-way, transmission of digitized video images between tw o or more locations. Teleconferencing requires a wideband transmission facility. Transmitted images may be freeze-frame (where television screen is repainted every few seconds to every 20 seconds) or full motion. Bandwidth requirements for two-way video conferencing range from 6 MHz for analog, full-motion, full-color, commercial grade TV to 56 kbps for digitally-encoded freeze-frame to 1.544 kbps for very good quality, full-color, full-motion TV.

wideband

Generally, a communications channel offering a transmission bandwidth greater than a voice grade channel. Data transmission speeds on wideband facilities are typically in excess of 9.6 kbps and often at rates such as 56 kbps and 1.544 Mbps.

128

ISU 128 User Manual

61202.029L2-1

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ADTRAN ISU 128 user manual 2B+D
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ISU 128 specifications

The ADTRAN ISU 128 is a versatile and robust integrated service unit designed for network access solutions, particularly within telecommunications and enterprise environments. This unit plays a critical role in enabling high-speed data transmission, supporting various voice, video, and data services over traditional and next-generation networks.

One of the noteworthy features of the ADTRAN ISU 128 is its ability to aggregate multiple digital circuits into a single access point. It supports T1, E1, and fractional T1/E1 interfaces, making it a flexible choice for customers with different bandwidth needs. The unit allows for seamless migration from legacy systems to modern broadband services, ensuring that businesses can scale their operations without significant infrastructure changes.

The ADTRAN ISU 128 also excels in its support for various protocols, including Frame Relay and ATM, providing the necessary flexibility to adapt to different network architectures. This adaptability is essential for businesses that rely on diverse communication platforms to maintain connectivity and operational efficiency.

Another significant aspect of the ISU 128 is its built-in features for diagnostics and monitoring. The unit includes comprehensive loopback and performance monitoring capabilities, which enable network administrators to troubleshoot potential issues proactively. This functionality ensures a reliable connection and minimizes downtime, which is critical for maintaining service-level agreements (SLAs).

In terms of user interface, the ADTRAN ISU 128 is designed with ease of use in mind. The unit can be configured and managed through a web-based graphical user interface, allowing for straightforward remote access to settings and performance metrics. This capability facilitates quick adjustments and upgrades, helping to streamline network management tasks.

The ISU 128 is also built with a strong emphasis on reliability and durability. It is housed in a compact, rack-mountable design, making it suitable for various deployment environments. These characteristics, combined with support for redundant power supplies, enhance the unit's reliability in critical operations.

Overall, the ADTRAN ISU 128 stands out as a powerful solution for organizations seeking to optimize their network access. With its advanced features, compatibility with multiple technologies, and emphasis on reliability, the ISU 128 is an ideal choice for those looking to enhance their communication infrastructure in a rapidly evolving digital landscape.
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