分组网与ISDN互连的研究

非ＩＳＤＮ网与ＩＳＤＮ互连是向ＩＳＤＮ过渡的策略之一，其中ＰＳＤＮ与ＩＳＤＮ的互连占有重要地位。本文研究ＰＳＤＮ与ＩＳＤＮ互连的技术问题，在对两种网比较的基础上，文中提出了几种可能的互连方案，并讨论了互连层选择、号码制度互通、流量控制、差错控制、信令转换、信关结构等技术问题和性能分析问题。     

Implementing ISDN in the United States

Planning for implementation of ISDN is proceeding at a rapid rate throughout the United States. Planning for nationwide deployment of common-channel signaling to support database access, as well as internode signaling for ISDN is also underway. This paper describes planning for trials and initial applications of ISDN and common-channel signaling for service starting in late 1986 through early 1988, as well as ISDN demonstrations, some already in operation. In addition, this paper discusses the network and regulatory environment for ISDN implementation in the United States, standards for the U.S. environment, and trials of transition services.     

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.     

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.     

Why are ISDN standards important?

The advantages offered by the integrated services digital network (ISDN) to US Department of Defense (DoD) communications in terms of interoperability provides a framework for a discussion of ISDN standards. The standards organizations working on ISDN and network protocol standards are described, and their relationship to each other is delineated. The status of the standards being developed is discussed, and those that would be of special interest to the US DoD are examined     

Virtual tree‐based multicast routing with a distributed numbering algorithm for WM‐ATM handover

The flexibility offered by the ATM transport mechanism and its potential capabilities, together with its compatibility with the B‐ISDN, makes ATM the prime candidate for the support of multimedia services over the wireless medium. However, technical issues remain to be resolved in relation to the feasibility of ATM for the support of mobility over the radio interface. This paper examines network issues in supporting handover in a wireless ATM network. In particular, analysis has been performed for a virtual tree-based network architecture. Results have shown that by using multicast transmission and by using a distributed numbering algorithm, the potential problems of cell-loss and cell-duplication have been eliminated. This revised version was published online in June 2006 with corrections to the Cover Date.     

Technology '89: telecommunications

The demonstration in late 1988 of an experimental broadband ISDN (integrated-services digital network) in Japan, which conforms to the draft international standards recommended by the International Telegraph and Telephone Consultative Committee (CCITT) is discussed. Other 1988 developments discussed are the commercial operation of TAT-8, the first transatlantic fiber-optic cable between the US and UK; wavelength-division multiplexing of up to 10 channels on a single fiber, using tunable semiconductor lasers; the push for digital cellular phones; deregulation in the US of very-low-power radio transmission; and progress in gateways and faxphones     

Standards: the blueprints for optical networking

The definition of standards for optical networking is a new work item for the International Telecommunication Union (ITU) 1997-2000 Study Period. The authors provide a brief overview of this nascent standards development effort, with a specific focus on key issues currently under discussion that, when resolved, will have far-reaching impact on the ultimate realization of “optical networking”     

ISDN protocols for connection control

The technical details of the integrated services digital network (ISDN) access protocols for connection control are described. These protocols are the ISDN physical layer, link layer, and layer 3, which are documented in International Telegraph and Telephone Consultative Committee (CCITT) Recommendations I.430, I.441, and I.451, respectively. Other work that supports or enhances these protocols is described. In particular, the ISDN protocol reference model, how it relates to the open systems interconnection reference model, and CCITT Recommendation Q.932 on service feature control on ISDN are discussed. Possible uses of ISDN, possible evolution paths, and some understanding issues related to ISDN are also described     

Overview of the GSM system and protocol architecture

The global system for mobile telecommunications (GSM), which provides terminal mobility, with personal mobility provided through the insertion of a subscriber identity module (SIM) into the GSM network, is discussed. Cellular mobile communications, the cellular network infrastructure, and the specification of network databases and standards are described. The GSMs, numbering plan, radio channel structure, mobility management, call routing and signaling, protocol layering architecture, signaling transport protocols, and paging messaging systems are also described     

Layer 1 ISDN Recommendations

In the framework of the I-series of Recommendations, layer 1 specifications for ISDN user-network interfaces are given in Recommendation I.430 for the basic access(2B + D)at 144 kbits/s, and in Recommendation I.431 for the primary access at 1544 and 2048 kbits/s. The former Recommendation contains a completely new set of procedural, functional, and electrical characteristics whose definition was started during the last CCITT Study Period and is expected to be completed by the end of the present CCITT Study Period. Moreover, the latter Recommendation is largely based on functional and electrical characteristics of existing Recommendation G.703, which gives specifications for the physical/electrical characteristics of the hierarchical digital interface.     

天津市建设N-ISDN有关问题的探讨

介绍了窄带综合业务数字网（Ｎ－ＩＳＤＮ）的业务特点及种类，对天津市建设Ｎ－ＩＳＤＮ的必要性、Ｎ－ＩＳＤＮ的网络结构和基本配置等有关建设方案和其他一些问题进行了初步的探讨。     

Introduction of Wide-Band Communications in the Telecommunications Network

An increasing demand for digital wide-band business communications has been emerging as a new driving force in the evolution of the telecommunication network. In parallel with this demand, new transmission, multiplexing, and switching technologies are becoming available to support the implementation of attractive end-to-end wide-band services. This paper looks at the application opportunities of wide-band technologies in the telecommunication network for both near and longer term use, and discusses key implementation and evolution issues. The paper also defines a wide-band channel structure plan as a basis for wide-band ISDN standardization.     

PHS roaming signaling protocol architecture toward global mobilitynetwork

The network for supporting the global personal communication is called the global mobility network (GLOMONET), where global mobility is guaranteed by coordination between intelligent networks (INs). This paper describes the implementation of a roaming signaling protocol for the personal handy-phone system (PHS) GLOMONET, clarifying the concepts of the PHS architecture regarding the GLOMONET. The PHS is a more economical personal communication system than existing cellular systems, by introducing the concept that the PHS service is provided by the most effective use of the existing ISDN and IN functions, where the majority of network functions to provide ISDN services are commonly used for functions for PHS service provision. The PHS mobility function realized by the IN guarantees flexible and effective roaming service provision for the globalization of future personal communication. The proposed PHS signaling protocol architecture is based on the intelligent network capability set 2 (IN CS2) defined by the International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Study Group 11 and a visitor location register (VLR) database scheme with efficient signal transfer in the GLOMONET. The PHS specific roaming signaling protocol is defined by the service-independent IN application protocol (INAP). The proposed PHS concepts and roaming signaling protocol were reflected to the national telecommunications standards in the Telecommunication Technical Committee (TTC) and standards in the PHS-memorandum of understanding (MoU)     

An Idea Turns Into Reality--CCITT Activities on the way to ISDN

This paper traces, in broad terms, how the idea of integration of telecommunication services into one network has evolved in the CCITT. A brief overview of existing telecommunication networks is followed by a review of CCITT activities from 1968 to 1980. It had become evident by 1968 that digital technology would not be restricted to transmission only, but would also intrude into switching, signaling, and the terminal field. The CCITT acknowledged this tendency by setting up a Special Study Group entrusted with the study of all questions related to PCM and the coordination of work going on in other Study Groups in the digital field. By 1980 the first ISDN Recommendation (G. 705) was agreed upon, and activities during 1980-1984, when the ISDN took shape, are related in some detail. The structure of the I-Series Recommendations, all relevant to ISDN matters, is described.     

ISDN: a snapshot

A snapshot of the present status of ISDN (integrated services digital network) is presented in terms of standardization efforts, field trials and demonstrations, implementations and services, and equipment and devices. A review of opinions and controversies as well as future trends is also given. The authors emphasize the importance of the worldwide standardization effort and discuss the organizations that are responsible for establishing such standards. It is pointed out that, with the limitation and inflexibility of the narrowband ISDN and the broadband ISDN, issues for higher-rate services have become prominent. For broadband services, the problem is not merely increasing the speed of the operation. It affects the compatibility of switching technology, the workability of the local loop arrangement, the availability of rate adaption, and the efficiency of bandwidth utilization. Although some basic principles of narrowband ISDN can be carried to broadband ISDN, the technology is quite different. For example, the interconnection and transmission problems of video, HDTV, (high-definition television), and high-speed data are different from those of voice. Thus, the standard 64-kb/s B channel itself, the fundamental rate of ISDN transmission, appears inadequate for wideband services. At present, the solution is to establish the multiples of 64 kb/s for accommodation of broadband or higher rates     

Interworking IEEE 802/FDDI LANs via the ISDN frame relay bearerservice

The author presents a generic architecture for interconnecting LANs (local area networks) through the ISDN (integrated services digital network) bearer services, particularly the frame relay bearer service. The architecture is derived from the IEEE 802.1 MAC (medium access control) bridge and ISDN frame relay standards. An algorithm for MAC/ISDN address resolution that makes minimal use of the WAN (wide area network) bandwidth (which is potentially the most expensive resource) is presented. The algorithm uses a MAC/ISDN address resolution server to resolve addresses for new stations, the resolution in all other cases (e.g. stations moving from the ISDN address to another) being fully distributed. To prevent a server failure from inhibiting communication to new stations, a backup server may be provided. A practical implementation of the architecture has been found capable of supporting full throughput at ISDN hyperchannel rates (384-1920 kb/s) for all IEEE 802.3 frame lengths. Frame relay is seen as having a number of important advantages for LAN interconnection, including the following: a large number of virtual circuits available, giving the potential for a rich interconnection architecture with single-hop connections across the ISDN; and low processing overhead enabling efficient use of ISDN channels, including ISDN hyperchannels (384-1920 kb/s)     

The role of ISDN in data networking

The integrated services digital network (ISDN) offers on-demand switched end-to-end digital connectivity over the wide area, enabling the integration of both voice and data services over a common core network. This paper considers the role of ISDN in data networking, both as the core transport network and as a means of enhancing resilience in a mixed-technology data solution, complementing other data network technologies. The issues associated with data transport based on an ISDN solution are considered, and include security, bandwidth utilisation, scalability and the management of ISDN-attached devices. Optimising the use of ISDN networks for supporting the most prevalent routed and routeing protocols is also discussed.