International standards for the broadband ISDN user-network interface

Recently, a series of international standards on broadband ISDN were approved in CCITT Study Group XVIII. These standards establish fundamental details on transmission, multiplexing and switching for broadband aspects of ISDN. This article reports on the current definition of the BISDN user-network interface. The UNI reference configuration, physical medium, rates, structure, ATM functions, and operations and maintenance functions are addressed with consideration given to open issues and the direction of future standards activities. Objectives for the UNI capabilities have generally been met with the current CCITT specifications. Some of the UNI physical layer ‘options’, however, potentially impose networking cost penalties.     

ISDN可视电话用户-网络接口协议的软件实现

对窄带ISDN用户－网络接口协议进行介绍与分析,并给出了一种窄带ISDN可视电话的终端协议软件的实现方法,包括D信道上的用户－用户信令过程和用户－网络信令过程。     

ISDN protocol architecture

IT IS NOW widely recognized that the Integrated Services Digital Network (ISDN) concept is providing a useful framework for the development of future telecommunications networks and services. An ISDN can be regarded as a generalpurpose digital network capable of supporting (or integrating) a wide range of services (voice and non-voice) using a small set of standard multipurpose user-network interfaces. Relevant CCITT Recommendations (or standards) on ISDN interfaces were expected to be available in 1984, the final year of the current study period. This paper reviews CCITT progress on the architectural studies of protocols associated with ISDN's, in particular, the ISDN Protocol Reference Model being developed by Study Group XVIII. This Model, based on the concepts and principles of the ISO/CCITT Open Systems Interconnection (OSI) Reference Model, aims at providing a unified framework for modeling ISDN multiservice communications and capabilities. The new Model is applied to several possible ISDN communications configurations, enabling a number of technical issues to be easily identified.     

The BUNI broadband user-network interface demonstrator network

Describes the BUNI (broadband user-network interface) Demonstrator Project (R1081) of the RACE programme which is concerned with the experimental implementation of the emerging standards for the broadband user network interface. The BUNI demonstrator network, comprising two broadband customer premises network and two broadband switches, is explained in some detail to give the reader an insight into the complexity of the complete demonstrator. The signalling concepts are described to illustrate the innovative nature of the project and to give an indication of the facilities which broadband ISDN will offer. An overview of the services which will be available at the BUNI demonstrator site is given     

GMPLS user-network interface in support of end-to-end rerouting

Carriers are enhancing their transport networks and improving their daily operations to address the increasing demand for (new) IP-based services. They require more scalable support for the increasing traffic demand and more flexible operations for connection provisioning. They are also seeking optimized resource utilization and time performance using faster and more robust recovery schemes while maintaining overall network costs. With advances in the GMPLS protocol suite including its user-network interface support, the possibility for better cooperation between transport and IP/MPLS networks is now possible. This article addresses this question by positioning and comparing the capabilities of the optical interworking forum's UNI with the Internet engineering task force's GMPLS UNI. Through three recovery scenarios, a quantitative analysis is provided that determines the gain obtained in deploying the GMPLS UNI over its OIF counterpart. Finally, a testbed demonstrating the feasibility and practicability of the GMPLS UNI implementation (which enables end-to-end connection rerouting) is presented.     

The ISDN U interface and transceiver

This paper describes the integrated services digital network (ISDN) basic rate interface (BRI) two-wire U interface and the transceiver necessary for the digital transmission of 160 kb/s of information over unshielded twisted pair transmission media. Topics discussed include the U interface structure and framing as described in the American National Standards Institute (ANSI) T1.601 specification, and the VLSI implementation of the ISDN U transceiver. Pertinent transceiver design issues addressed include the type of line code used, such as 2B1Q or 4B3T, echo cancellation, near end crosstalk, equalization and sampling rates.     

Circuit design and transmission performance of ISDN basic interface

An LSI-based user-network interface circuit, applicable to a network terminal (NT) for the integrated services digital network (ISDN) basic interface is developed. Adaptive timing extraction, with a simplified polyphase phase-locked oscillator, is introduced into the circuit for application to both point-to-point and passive bus configurations. This circuit does not require any manual adjustment. In addition to the primitives defined by CCITT between layers one and two, a new primitive is adopted for controlling the transmission of information. This primitive avoids premature transmission due to processing delays in the exchange terminal (ET). The above functions are fabricated on a CMOS gate-array LSI chip with 4000 gates. The performance of the interface circuit is confirmed with special attention to transmission and electrical characteristics     

Distributed resource management and connection control for a multi-access interface to a broadband ISDN (BISDN)

A customer premises network (CPN) provides a common communications fabric to efficiently integrate the traffic of multiple terminals on a common access interface to a BISDN. An important consideration in choosing a CPN architecture is to facilitate terminal portability and application transparency, so as to accommodate standard broadband terminals and applications, requiring only minor modification to adapt them from the standard BISDN interface to the multi-terminal environment. This paper explores the multi-faceted issues of CPN transparency with an emphasis on the evolving BISDN control and management architecture. We introduce a control architecture that conforms to a rigorous separation between ‘call control’ and ‘connection management’. This allows the CPN to be transparent to the user to network signalling exchange, and to participate only in the connection management via a remote resource management protocol. More generally, this scheme allows a call control entity located in a local exchange node (LEN) to manage a distributed set of resources such as switches and multiplexors (and CPNs). This is achieved through the definition of a standard interoperable interface between the central call control entity and the connection control entities which may be remotely located in various network elements. The features and functionality for such an interface, which we term the bearer connection control interface, are described within the framework of the OSI remote management architecture. A standard remote resource management protocol allows for the co-operative sharing of resources across administrative domains. Although the importance of such a scheme is particularly visible as applied to remote CPN management, it is useful in other application domains where it is advantageous to distribute management processes.     

Standardization of a multi-configuration medium access protocol for broadband ISDN

This paper examines the current work within various standards bodies to define a multi-configuration medium access control (MAC) protocol for operation between broadband ISDN terminals. To begin, the configurations in which the MAC protocol is expected to operate are introduced. The relation between the MAC protocol and the broadband ISDN resource allocation schemes is then discussed. Several MAC protocol proposals currently being discussed in various standards bodies, each with unique assumptions regarding resource allocation in broadband ISDN, are then described and compared. Finally, areas for future work on this topic are identified.     

A mail and protocol conversion node for ISDN facsimile application

An adapter for conventional G3 facsimiles for communicating over an ISDN network (INS NET-64) is presented. Its external functions, architecture, and control structure are described. The adapter is targeted for a transitional market and is intended to provide reduced communication costs     

Evolution of ISDN towards broadband ISDN

Worldwide activities to evolve integrated services digital network (ISDN) into an optical-fiber-based universal broadband network have resulted in the first baseline documents, such as CCITT Recommendation I.121. The asynchronous transfer mode has been established as a key element of broadband ISDN (BISDN). The adoption of the G.707-709 recommendations on the new digital transmission hierarchy will also strongly influence further BISDN development. The author presents the current state of the BISDN discussion, especially within CCITT, briefly addressing broadband services and then concentrating on the user-network interface, as its definition is of utmost importance with respect to the introduction of a worldwide unique BISDN. Network scenarios and evolution and interworking aspects of the arising broadband realizations are also addressed     

Broadband ISDN resource management: the role of virtual paths

It is shown that virtual paths will be a substantial component of a resource management control hierarchy for the B-ISDN. Other components of this hierarchy include connection admission, usage parameter control, and reactive congestion control. An overview of this control hierarchy is provided. The role of virtual paths for cost-effective resource management and connection admission control in the B-ISDN is examined. Some strategies for reserving capacity on virtual paths are identified, and the use of virtual paths to simplify connection admission control is discussed. The reservation of capacity on virtual path connections is shown to result in substantial network cost savings for the case study considered     

ISDN standardization

The history and achievements of ISDN (integrated services digital network) standardization in the CCITT are reviewed. Two of the most important developments, ISDN basic and supplementary services and broadband ISDN, are focused upon. The underlying concepts in the discussions of ISDN standardization are briefly explained     

Design and analysis of a bandwidth management framework forATM-based broadband ISDN

When designing and configuring an ATM-based B-ISDN, it remains difficult to guarantee the quality of service (QoS) for different service classes, while still allowing enough statistical sharing of bandwidth so that the network is efficiently utilized. These two goals are often conflicting. Guaranteeing QoS requires traffic isolation, as well as allocation of enough network resources (e.g., buffer space and bandwidth) to each call. However, statistical bandwidth sharing means the network resources should be occupied on demand, leading to less traffic isolation and minimal resource allocation. The authors address this problem by proposing and evaluating a network-wide bandwidth management framework in which an appropriate compromise between the two conflicting goals is achieved. Specifically, the bandwidth management framework consists of a network model and a network-wide bandwidth allocation and sharing strategy. Implementation issues related to the framework are discussed. For real-time applications the authors obtain maximum queuing delay and queue length, which are important in buffer design and VP (virtual path) routing     

Multi-rate ISDN

Multi-rate integrated services digital network (ISDN) is a new technology for providing dialed-up, circuit-switched, isochronous communications for bandwidths from 128 kb/s to 1.536 Mb/s (DS-1) or 1.920 Mb/s (CEPT-1). Multi-rate ISDN provides a simple way to extend ISDN network services to match the higher bandwidth requirements emerging for videoconferencing, multimedia, imaging, and other high-speed applications. Using this technology, network service providers can offer high-speed connectivity within the boundaries and benefits of existing, circuit-switched, central office and transmission equipment. Only minor changes are required in the operations administration and maintenance and provisioning (OAM&P) procedures associated with multi-rate ISDN, versus existing ISDN transmission and central office maintenance procedures     

Personalizing ISDN

It is argued that making integrated services digital networks (ISDNs) more popular among personal computer users is essential for ISDN to prosper. Users in offices, businesses, and at home form a large potential ISDN market. Existing ISDN interface modules such as ISDN adapter boards for personal computers, are limited to ISDN features and can hardly handle the various needs of personal users. An ISDN interface module for personal computers must be designed to handle various applications and provide any-to-any communications. An ISDN personal computer interface developed to handle digital and analog communication protocols and flexibly combine resources is described     

Narrowband ISDN and broadband ISDN service and network interworking

For a significant period of time, B-ISDN will coexist with the 64-kb/s-based (narrowband) ISDN. The specification of a concept and the mapping functions employed for interworking between the two networks, in particular for voice services, is a major factor for the success of B-ISDN