Signalling with objects

Conventional signalling systems, such as Q.931 and Q.2931, have grown from simple techniques for creating a single connection between two parties. However, with the B-ISDN, it will be desirable to be able to construct multiparty, multiconnection calls for multimedia services. This paper highlights the work done by the RACE MAGIC project to develop a new object-based signalling protocol to meet these requirements, and describes how this new protocol overcomes the shortcomings of conventional signalling.     

Evolving from narrowband [ISDN]

A nodal system architecture developed by Nippon Telegraph and Telephone (NTT) that will allow stepwise evolution to broadband integrated services digital network (B-ISDN), starting from the current nationwide narrowband integrated services digital network (N-ISDN) system in Japan, is discussed. The status of the current N-ISDN and the requirements for B-ISDN as the next step after N-ISDN are discussed, followed by a scenario for the evolution of B-ISDN from N-ISDN. A plan is outlined for the first ATM switching service for high-speed data transfer and a nodal system architecture permitting easy evolution to full B-ISDN     

B-ISDN: a technological discontinuity

The transition to B-ISDN from current networks represents a major technological discontinuity for the communications world. These discontinuities must be considered for the successful evolution of existing networks to broadband networks. The authors provide an overview of B-ISDN data transfer protocols and the services it will support. They discuss the effects of B-ISDN switching, network operations and management, signalling protocols and architectures, and networked computing     

Requirements for B-ISDN signalling — broadband services

The broadband ISDN (B-ISDN) is being tailored to become the universal (standardised) future netowrk, and will be capable of supporting a wide range of multimedia, multi-party applications. It is based upon the same principles as its narrowband predecessor and hence can be regarded as a natural extension of it. However, the move away from constant bit rate circuit switching towards the use of asynchronous transfer mode (ATM) technology has provided much needed flexibility, especially in terms of the connection bandwidths and quality of service available to the user.This paper briefly describes the network capabilities that B-ISDN should support and how they have been derived from a representative sample of user applications principally proposed by ITU-T/ETSI and Digital Audio-Visual Council (DAVIC). The identification of the required network capabilities is the first step towards the specification of signalling protocols for the B-ISDN which must be flexible enough to support the wide range of current and future advanced applications and services. One such potential future B-ISDN application, which demonstrates the range of signalling functionality required, is the 'Travel Agent Service' which is treated in detail.     

Traffic management for B-ISDN services

A set of asynchronous transfer mode (ATM) bearer service categories, differentiated in terms of quality of service (QOS), that will support the large spectrum of applications expected in broadband integrated services digital networks (B-ISDN) is defined. The evolution of applications and the traffic requirements in B-ISDN/ATM networks are described, and the evolution of network services to address these requirements is discussed. The definition of ATM bearer service categories necessary for the economical support of initial applications and evolution to future B-ISDN services is proposed. The elements of the ATM traffic management strategy to support these service categories are presented     

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.     

Connection architecture and protocols to support efficient handoffs over an ATM/B-ISDN personal communications network

The next generation personal communication network will likely internetwork wireless networks via the ATM/B-ISDN to enable ubiquitous broadband personal communication services. Support of user terminal mobility, particularly the capability for fast and seamless handoffs, over the ATM/B-ISDN is an expected requirement that is not currently met. We propose extensions to the ATM/B-ISDN user transport and signaling network architectures and signaling protocols to meet these requirements. The new architecture employs the Mobile Virtual Circuit (MVC), a dynamic connection tree in which routes are predetermined but not set up for potential handoff connections. During a handoff, associated signaling using source-routing with a new robust adaptation feature is employed for fast resource allocation to establish the handoff connection by distributed control. We also address the new problem of packet ordering synchronization to enable a seamless handoff. The connection tree reconfigures after each handoff to enable continuous support of successive handoffs. The proposed scheme optimizes handoff delay over the ATM/B-ISDN while minimizing unnecessary resource allocation, chances of handoff failure, and call processing load in the intelligent network, and the extensions are backward compatible to current ATM/B-ISDN standards and implementations.This paper was presented in part in PIMRC'95 in Toronto, and Globecom'95 in Singapore. This work was supported by the Canadian Institute of Telecommunications Research (CITR), funded under the Canadian Federal Government's Networks of Centres of Excellence Program.     

A multilevel framework for the attribute description of telecommunication services

Telecommunication services are traditionally described from the terminal viewpoint, including the user interaction with the service, as well as the specific terminal characteristics to the network that it is meant for. Also traditionally the instance of the telecommunication service was a call and a connection as a one-to-one couple. Nowadays networks with powerful multimedia/multiconnection/multiparty capabilities require that a telecommunication service should not be described any more as a conglomerate, but by its main service elements, which in turn are supported by other service elements, so that a service may be built up by building blocks in a levelled model. The criteria to be considered to find these elements are the user viewpoint, the information coding (or terminal) viewpoint and the network access viewpoint. This leads to the telecommunication service, party, party edge, user service module and abstract service module as pure user-dependent service elements, the service module for the terminal aspect, and the access connection element for transfer of the information over the network. All these basic service elements are ordered in a levelled structure called a multilevel framework. Each level or co-level represents a service element type which may be instantiated as a service object, and which is described statically by a table of attributes. Attributes for each level are listed and clarified. An example describing a well-known service is given to illustrate the use of the framework. The views expressed in this document have been developed by the RACE 2044 MAGIC.

1 RACE: Research into Advanced Communication Technologies for Europe. MAGIC: Multi-service Applications Governing Integrated Control.

The concepts presented are related to Release 2 and 3 for BISDN as defined in ITU-T.     

Quality of service in telecommunications. I. Proposition of a QoSframework and its application to B-ISDN

The the quality of service (QoS) concept is becoming an ever more important issue in telecommunication and computer communication. The article focuses on the QoS notion and concept. The definition of QoS in the International Telecommunications Union-Telecommunications Sector (ITU-T) recommendations and the International Standards Organization (ISO) standards is analysed. Little is known about the asynchronous transfer mode (ATM) performance requirements of the broadband integrated services digital network (B-ISDN) services, especially for multimedia applications. This is because the ATM performance requirements of multimedia applications depend not only on the diverse QoS requirements from application and user, but also on the protocol stacks and scheduling in end systems. Therefore, in order to guarantee QoS to the user, it is necessary to introduce a set of QoS parameters whose properties indicate the nature and requirements of the layered protocol stack. We describe how a proposed QoS framework can be applied to B-ISDN as a specific network. The QoS aspects related to B-ISDN signaling (the control plane) and the QoS aspects related to layer and plane management (the management plane) are described. We also describe how the QoS framework resides in a protocol stack and works together with the B-ISDN network management and signaling     

Implementing the Orwell protocol over a fibre-based high-speed ATMnetwork

Asynchronous transfer mode (ATM) has emerged as a possible contender for the next generation switching system and fundamental transport basis for the broadband integrated services digital network (B-ISDN) and telecommunications in the future. It is widely thought of as the network to accommodate the uncertain requirements of future public communications because of its high degree of flexibility and service independency. The Orwell protocol developed by British Telecom can provide a communication base to meet the requirements of such a network. Orwell is used as a slotted ring protocol designed to carry a mixture of services which form the basis of an ATM network. The authors describe the realisation of a 155.52 Mbit/s fibre-optic physical layer from the Orwell protocol based on an ATM technology, and also discuss how the Orwell protocol can offer broadband transport capabilities and can provide access to and interwork with existing networks, such as telephone networks and 64 kbit/s based ISDNs     

Konvergenz der Kommunikationsnetze zu Multiservice-Netzen

The rapid progress in the convergence of communication networks (fixed and mobile networks with data networks) to multi service networks has an impact on the principles of the traditional switching technologies. Future requirements will also have to be fulfilled through service-convergence (bundling of individual services to new services) regardless of organizational or technical boundaries. Requirements in the information- and communication-business all the way to technical network aspects are to be faced. Based on developments in microelectronics, two converging evolutions by packet-oriented technologies (within the network and at the edge of the network) are now taking place. Starting with the principles of circuit-switching and packet-switching the change in today’s telecommunications world will be discussed. Apart from that emphasis will be put on the distribution of the switching functions within the network, the change of the network’s topology, as well as the influence on the signalling protocols (extensions and new approaches).     

INSIGNIA: a pan European trial for the intelligent broadbandnetwork architecture

This article summarizes the work carried out within the ACTS project INSIGNIA, which is targeted at the provision of interactive multimedia services through IN and B-ISDN integration. The basic concepts regarding the integrated approach are discussed with emphasis on the functional architecture. This discussion is followed by a presentation of IN multimedia services which were created based on these principles. An overview of the real-life trials which were conducted on a pan-European basis in order to evaluate the INSIGNIA services is also given. The results of this evaluation are examined from a variety of viewpoints, including functional architecture, user and network equipment, service logic programs and applications, as well as user acceptance and network performance     

Frame relaying as a common access to N-ISDN and B-ISDN dataservices

Widespread use of personal computers (PCs) and PC networks is leading to a strongly increased demand for WAN data services in terms of number of accesses and required bandwidth. Narrowband ISDN (N-ISDN) and broadband ISDN (B-ISDN) have the potential to satisfy, respectively, the existing and developing requirements. However, a flexible evolution path needs to be identified for the provision of ISDN access facilities. Frame relaying and frame switching are prime candidates for such a common access facility, although not necessarily intrinsic B-ISDN data services. The article gives an overview of frame relaying and frame switching as possible candidates for harmonized access to N-ISDN and B-ISDN. Pre-ISDN, N-ISDN, and B-ISDN services with their characteristics in terms of cost and performance are first described. It is shown how frame relaying and switching are positioned with respect to the identified service requirements. Then some examples are given of selected scenarios, and the role played by specifically frame relaying to provide access to B-ISDN services, offering at the same time a seamless evolutionary path from N-ISDN to B-ISDN. The position of frame relaying and switching is discussed first in respect to application requirements, and then in architectural terms. Frame relay (and frame switching) services are then identified as services that provide the necessary low threshold and short lead time for rapid market penetration, in order to allow applications to indirectly take advantage of the benefits of ATM services     

ATM shared-memory switching architectures

ATM will provide flexibility in bandwidth allocation and will allow a network to carry heterogeneous services ranging from narrowband to wideband services. The challenge is to build fast packet switches able to match the high speeds of the input links and the high performance requirements imposed. The CCITT has standardized the asynchronous transfer mode (ATM) as the multiplexing and switching principle for the broadband integrated services digital network (B-ISDN). ATM is a packet and connection-oriented transfer mode based on statistical time division multiplexing techniques. The information flow is organized in fixed-size packets called cells, consisting of a user information field (48 octets) and a header (5 octets). The primary use of the header tag is to identify cells belonging to the same virtual channel and to make routing possible. Cell sequence on a virtual channel is preserved, a very low cell loss probability must be guaranteed (< 10^-12), and intensive error and flow control protocols are provided at the edges of the network     

An early implementation of a DAVIC V1.0 system — use of dynamic connections for interactive multimedia services

Advances in networking technology and the provision of greater wide area bandwidths are the catalysts for the emergence of new broadband services in both the business and residential market. This is in turn producing new, more complex, business models involving service consumers, content providers, service brokers and network connectivity providers. Such business models require the underlying technology to enable sophisticated network signalling to set up, monitor and tear down connections reliably and in real time.This paper describes the evolution of a broadband call control demonstrator believed to be the first of its kind in the world to provide a practical realisation of the signalling required in such business models. It focuses on signalling and switch control and has developed into an end-to-end implementation of a Digital Audio Visual Council (DAVIC) V1.0 system.The evolution of the switch control and signalling architecture is described, showing where existing standards have been implemented to provide basic connectivity across an ATM network. Additional capabilities are built upon this platform through the adoption of emerging signalling concepts, such as session control, and application control using distributed object-oriented principles, for the access and control of a video-on-demand service.To further understand the evolutionary path for emerging consumer systems, the paper illustrates how work was undertaken to separate set-top box (STB) functionality into a set-top unit (STU) and a network interface unit (NIU), allowing easier access to future broadband network capabilities.     

Modeling call control for distributed applications in telephony

The advanced intelligent network (AIN) architecture, an environment in which distribution applications are designed, developed, and deployed independent of the network implementation by different service developers, on possibly different platforms, at different times, is considered. The focus is primarily on support for call-processing applications through call-modeling techniques. However, the entities of NECs application service processor (ASP) architecture as a whole are briefly described to provide a basic understanding of the scope of the call model. The call-modeling concepts discussed at the Bellcore-sponsored Multi-Vendor Interaction forum are compared with NEC's call-modeling concepts. A simple approach (i.e. the logical path) for controlling the execution of FCs (function components) when multiple AIN services are active on a call is suggested. An object-oriented implementation based on the NEC call model is described     

ATM: customer needs in the transition to B-ISDN

The development of the broadband integrated-services digital network (B-ISDN) is part of the continuing evolution of the telecommunications network. The author considers the expected rate of increase in information-carrying capacity to the general public and its needs for interfacing and service. He proposes a technique of shaping/policing the channel capacity which will be easily understood by both user and network provider. Finally the uncertainties that remain in the way that applications may exploit the ATM network and the consequent different needs for signalling and control have been highlighted     

Self-healing virtual path architecture in ATM networks

ATM network techniques have been actively researched and developed with the goal of realizing B-ISDN. ATM networks can transport signals of various services efficiently and economically, and offer the benefit of enhanced flexibility if the virtual path (VP) concept is adopted. Therefore, the ATM network will provide the infrastructure for B-ISDN. One of the most important themes in B-ISDN is the increased level of network reliability required to to match the high volume of data transmission that will be incurred by the information society and the “mission critical” nature of such data. The authors summarize self-healing network (SHN) schemes they have developed, and discuss problems that must be solved to realize SHN     

B-ISDN multimedia workstation architecture

Technical issues involved in integrating computer and communication technologies in the broadband integrated services digital network (B-ISDN) environment are discussed. The Multimedia Environment for Remote Multiple-Attendee Interactive Decision-making (MERMAID), an ISDN-based multimedia and multiparty desktop conference system, is described. MERMAID involves B-ISDN key technologies related to multimedia and multicast protocols, and workstation architecture for groupware applications. Technical issues based on user experiences and evaluations of MERMAID over three years are presented and discussed in connection with the system's evolution in the B-ISDN environment