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.     

城域网与B－ISDN

本文首先阐述了应用需求是如何促进宽带高速网络发展的，然后在说明现有通信网技术的缺点和比较两种过渡技术的基础上，指出利用城域网过渡到Ｂ－ＩＳＤＮ的优点，最后提出现有通信网通过城域网技术逐步演变成Ｂ－ＩＳＤＮ的基本设想。     

Research on Advanced Switching Techniques for the Evolution to ISDN and Broadband ISDN

Switching techniques for packetized data and for video communications are a key element in the evolution of the central office from IDN, to ISDN, and to broadband ISDN. An evolutionary scenario, based both on a short-term and on a longterm reference architecture for the switching system, is proposed, and two advanced switching techniques for labeled switching and for diffusive video switching, respectively, are analyzed which match the above scenario well. Plans and preliminary results are also reported on experimental research through laboratory demonstrators of the two switching techniques.     

Broadband communication and its realization with broadband ISDN

In addition to narrowband services, future broadband networks will also include broadband services for applications like: high-speed communication of data, text and graphics person-to-person video communication, access to video information as well as broadcast of programs and data. Low terminal costs and service charges are essential with respect to a growing demand for new services, especially in the home. Broadband ISDN, to be developed on the basis of ISDN and using glass-fiber subscriber lines, will enable a wide range of applications satisfying the needs and requirements of the business and private sectors. The best technical solution from the aspect of user-friendliness and economy is to implement this broadband ISDN for all services with an evolutionary and flexible design. The broadband ISDN concept is not restricted to the public network and terminal equipment but also comprises private networks, information and program centers, etc. Many countries are pursuing the goal of this universal network for the future "information society". However, the approaches for setting up the broadband ISDN differ from country to country, depending on the particular technical and political situation. Standardization plays an important role with regard to "open broadband telecommunication", the worldwide trouble-free communication and information exchange of one party with any other.     

Technology Aspects for System 12 Broadband ISDN

Although the enhancement of System 12, SEL's digital switching system, for ISDN services is virtually complete, further development work is being carried out to allow broadband switching for videophone services, videoconferencing, and the distribution of radio and television programs. This paper describes an appropriate approach to the evolution Of System 12 toward the broadband ISDN (B-ISDN), emphasizing the crosspoint and technology aspects of the broadband switch. Test results on a broadband switch VLSI circuit for 140 Mbit/s in a 2μm CMOS technology are presented.     

Broadband ISDN and asynchronous transfer mode (ATM)

The transfer mode chosen by the CCITT Study Group XVIII Task Group on ISDN Broadband Aspects as the basis of broadband ISDN is called the asynchronous transfer mode (ATM). ATM is a high-bandwidth, low-delay, packetlike switching and multiplexing technique. It is essentially a connection-oriented technique, although it is envisioned as a basis for supporting all services, connectionless as well as connection-oriented. The basic transfer mode concepts are explained. The limits of synchronous transfer mode (ATM) are discussed and reasons for choosing ATM over STM are given. The main technical issues having an impact on the ATM specifications are discussed     

High-Speed Time Division Switching Technique for Broadband ISDN

A key point in realizing broadband switching networks is architectual efficiency for switching various types of traffic with speeds ranging from several kbits/s to several Mbits/s. We propose a new switching technique, that is, a high-speed time division switching based on the single slot switching technique. This technique has several switching modules corresponding to standardized bit rates of traffic, and each cell is switched in the switching module corresponding to its speed. With this technique, all types of traffic will be equivalent with respect to the grade of service. This paper outlines its principle, clarifies the performance of traffic capacity,and finally proves its feasibility.     

Broadband ISDN Switching Capabilities from a Services Perspective

Broadband switching and transmission technologies are maturing rapidly, promising to make broadband ISDN (B-ISDN) possible and potentially economical in the near future. The diversity of possible B-ISDN services provides much impetus for the implementation of B-ISDN, but complicates the task of specifying network switching requirements. This paper examines a few representative services in order to generate a set of basis vectors in capability space. New services are then projected onto this basis; if a new service cannot be constructed from the basis vectors, other vectors are added to the basis set. B-ISDN architects can then specify switching requirements by selecting those capability basis vectors that are required for the services most in demand. For full motion entertainment video services, circuit switching capability at about 150 Mbit/s may be required, while selective broadcast and remote switching capabilities may reduce the cost of these services. For subvideo-rate services, new transfer mode (NTM) capability may be required to allow users the flexibility to allocate access channels dynamically on a per-call basis. Multiple connection (e.g., voice and video) and multiple party call capabilities may be required for many B-ISDN services, implying a need to extend the ISDN signaling protocol. The capability for the user to request network code conversion between different coding formats (e.g., NTSC or HDTV), and network compression of signals to reduce the cost of interoffice facilities, may also be required. Finally, fast call setup capability and high calling volume capabilities may be required, implying a need to distribute call processing functions over multiple processors in the central office.     

Broadband ISDN — service visions and technological realities

Two forces, service needs and technological advances, are driving the extension of the Integrated Services Digital Network (ISDN) into the broadband area. First, this paper identifies several business and residential services which provide a market pull for broadband ISDN (BISDN). Secondly, it reviews recent advances in optical transmission and broadband switching which provide a technological push. Finally, it describes an experimental broadband prototype constructed to help us better understand the transmission, switching, signaling protocol, software, and service capabilities required for BISDN.     

Synchronous Composite Packet Switching-A Switching Architecture for Broadband ISDN

A new switching architecture for broadband ISDN, "Synchronous Composite Packet Switching (SCPS)," is proposed and evaluated. It efficiently integrates circuit and packet switching functions on a single switching system and accommodates very high speed-up to several tens of Mbit/s-communication services, such as very high speed bursts of data, still picture, and motion video, as well as 64 kbit/s or less voice and data services. The SCPS system comprises plural switch modules and plural Very high speed synchronous loops. In the SCPS system, messages on plural circuit switched channels are assembled into quasi-packets, called "composite packets," and switched synchronously between switch modules, maintaining complete time transparency and short absolute delay time. A system parameter design to obtain high system efficiency and appropriate system modularity is explained, and an example for a very large capacity transit switch of 4 Gbit/s throughput is presented. System implementation problems to realize the SCPS principle, such as efficient implementation of the composite packet assembling and loop transmission functions, are investigated and an experimental system constructed for circuit switching part is presented. The most remarkable characteristic of the SCPS is that it efficiently integrates64 times nkbit/s circuit switching with packet switching. Moreover, the SCPS system retains compatibility with existing networks and the possibiliy of evolution toward a future broadband ISDN. On the basis of the above investigations and experimental system construction, the authors conclude that the SCPS is one of the most practical switching architectures for the coming broadband ISDN era.     

Broadband public network and switch architecture

The authors present a view of public network and switch architecture evolution to broadband capabilities, driven by the applications evolutions and built on a synchronous fiber transmission infrastructure such as SONET (synchronous optical network). The scenario is based on the partitioning of broadband network functions between synchronous fiber transmission systems and cell-based transport. The first stage of evolution incorporates frame-based switching to support increasing data traffic for LAN (local area network) interconnections. Cell-based technology appears first in the form of point-to-point high-speed data trunks and then as switched high-speed access. Centralized cell switching will provide interconnect between cell-based trunks and shared access lines. Remote cell multipliers will provide traffic concentration when the number of customers further increases. Since cell transport will first be introduced in the network as an extension of frame transport to higher speed, interworking between cells and frames will be necessary     

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     

宽带ISDN与ATM交换技术：第五讲 宽带业务应用与ATM网络的发展策略

本文分析了宽带业务的应用，讨论了ＡＴＭ网络与现有各种网络的互通问题，并概述了Ｂ－ＩＳＤＮ网络的发展策略。     

Broadband networks and services: architecture and control

Broadband networks to support a diverse combination of media and services present two interrelated challenges to the designers: how to devise the proper network architectures to efficiently deliver information, and how to realize the control and software infrastructure for end-to-end support of broadband applications. The new networks and applications that represent the future of interactive digital broadband are not driven by technology alone. We should recognize that the true foundation of the future information networking business involves the uses and benefits that it produces. The applications that are driving the information age are numerous, coming from the areas of entertainment, enterprise systems, telecommunications, education, health, etc. The use of client-server distributed object computing technologies is at the foundation of all the software systems that have been designed and implemented. There are still many Issues to he resolved in the application of this software technology, but it is clear that we must rely on distributed software designs to support the features of interactive broadband services. Concerns over the ability to manage complexity and scalability in these large distributed software systems are a common thread and an indication that the technology still needs to mature     

Broadband ISDN ATM layer management: operations, administration,and maintenance considerations

An overview and characteristics of the broadband integrated services digital network (ISDN) that is based on asynchronous transfer mode (ATM) is presented. ATM layer management across the user network interface (UNI) is discussed. The UNI is described, as are the ATM cell structure and its role in management protocols. There are two management protocol models which are explained; however, the focus is on the ATM layer management protocol. An overview of network management functions is provided. Some examples of ATM layer management functions based on the generic functions are provided     

A pipelined, multiprocessor architecture for a connectionlessserver for broadband ISDN

The direct provision of connectionless service in BISDN calls for servers that are connected to or are part of an ATM network to provide the routing function at input speeds up to 622 Mb/s. Routing is achieved in such a server by changing the VCI/VPI headers in the ATM cells; actual switching is done by existing switches in the ATM network. The paper presents an architecture capable of executing all the functions of a server at input speeds up to 622 Mb/s, scalable to multiple inputs at that speed, making use of processors and special hardware that are available today. To avoid storing large quantities of data, the architecture routes data packets by examining routing information in the initial cell of the packet and routing subsequent cells as they arrive rather than waiting until the complete packet has arrived. It is capable of handling packets that have been multiplexed at the SAR sublayer using AAL Type 3/4 and, with minor modifications, could also handle Type 5 traffic. Arguments are also presented for the use of AAL Type 5 for the direct connectionless service