B-ISDN and the OSI protocol reference model

The evolution of public telecommunication networks toward broadband integrated services digital networks (B-ISDNs) is presented. The asynchronous transfer mode (ATM), which supports B-ISDNs, and the B-ISDN protocol reference model are discussed. It is shown that the service offered by the ATM layer in the B-ISDN protocol reference model is equivalent to the service offered by the OSI physical layer. It is also shown that the service offered by the ATM adaptation layer (AAL) type 3/4 is similar to an OSI data link service. The emergence of the metropolitan area network (MAN) standard as an intermediate support for broadband services and the similarities between the DQDB MAC and the AAL type 3/4 in its connectionless mode are discussed     

Developing a cohesive traffic management strategy for ATM networks

The background and some of the rationale for the development of an asynchronous transfer mode (ATM) traffic management framework to support the wide variety of services to be carried over the B-ISDN are discussed. The advantages of statistical, as opposed to deterministic, multiplexing are examined. Given the anticipated B-ISDN service characteristics, two classes of quality of service are defined based on cell delay and cell loss. The key ATM traffic management tools are reviewed. These tools are broadly classified as either preventive, limiting the total amount of traffic admitted to the network in order to virtually eliminate probability of cell-level congestion, or reactive, assisting the network and individual connections to avoid the onset of congestion and minimize its severity when it does occur. A strategy for the initial introduction and the long-term evolution of an ATM traffic management framework is described     

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     

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     

The infrastructure for gigabit computer networks

The key features of the synchronous optical network (SONET) and asynchronous transfer mode (ATM) standards for the broadband integrated services digital network (B-ISDN) public network, which is expected to provide a powerful and ubiquitous infrastructure to support the emerging gigabit-per-second data and multimedia applications, are reviewed. The advantages of ATM, the ATM cell format, the B-ISDN protocol reference model and the ATM layer, the ATM adaptation layer, and ATM traffic management and signaling are discussed. An experimental high-performance parallel interface (HIPPI)-ATM-SONET interface is presented as an example to illustrate how the SONET and ATM techniques can be used to provide end-to-end transport for applications requiring a bandwidth of 800 Mb/s and possibly 1600 Mb/s     

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     

Integrated open service node for active networks and services

The changing business scenario for telecommunication services requires higher levels of openness compared to current technologies. The realization of a programmable and open network intelligence fosters the transition toward an open telecom market. This extended openness is requested to allow flexible component-based service integration; extended control/management capabilities are needed for new electronic business infrastructure, more service personalization and programmability, and integration and management of heterogeneous networks (Internet/B-ISDN/mobile, etc.). We present an integrated architecture for active and programmable networks and services based on the concept of an integrated service node. We study the business point of view, the B-ISDN/ATM point of view, and the Internet point of view. Each of these technologies is supported by an adapted and adaptive service node to introduce advanced service composition, control, and management capabilities. We present a possible implementation infrastructure, and discuss related issues     

A service architecture for ATM: from applications to scheduling

This article derives a rationale for the service architecture of the ATM Forum's Traffic Management 4.0 specification. This model distinguishes a small number of general ways to provide quality of service (QoS) which are appropriate for different classes of applications. We construct the set of ATM service categories by first analyzing the QoS and traffic requirements for a reasonably comprehensive list of applications. The most important application properties and the complexity of the related network mechanisms are used to structure the services. This method has the desirable property that the number of service categories does not expand rapidly with the introduction of new applications. We also discuss packet scheduling as the key component for realizing such a set of services, and report on an experimental realization of a fair queuing scheduler     

ATM in MPLS-based converged core data networks

Services supported by asynchronous transfer mode account for the majority of data and Internet service revenues generated by carrier networks today. This is based on ATM's ability to support high availability services with quality of service. However, the influences of the Internet and a highly dynamic telecommunications market have raised demands for increased flexibility while controlling costs. Therefore, future carrier networks are likely to continue to be based on established technologies, such as ATM, as well as IP. In many cases, this is achieved through maintaining separate ATM and IP core networks, with the IP network supporting Internet services, while the ATM network continues to support guaranteed services such as private lines, broadband access, and video. In some cases, however, it can be advantageous for a carrier to transport segments of their ATM network over their IP network core; for example, to transport ATM traffic currently carried on leased facilities onto an IP network where the service provider owns the facilities. Developments in IP and MPLS-based traffic engineering and QoS may increase the ability of IP-based networks to support ATM services using MPLS. This article provides an overview of approaches enabling a network based on MPLS that naturally supports IP services to also support ATM services. The drivers and requirements for convergence on an IP/MPLS core network are presented, followed by an overview of the different approaches and associated challenges currently being debated in the standards bodies.     

A multimedia STM switch prototype

There is no doubt the concept of ATM (asynchronous transfer mode) has gripped the technical community and has raised the hope for truly integrated voice, data, imaging, and video services. Such a dream was never possible before because of the diverse bandwidth requirements of each service type. Existing narrowband switches could not possibly keep up with widely varying channel bandwidth or the enormous aggregate bandwidth required. New methods of signaling would also be required to support new broadband services. The signaling itself might need varying degrees of bandwidth, and would likely be carried in the same stream as the data, yet be easily distinguishable. A common unit of information in the form of a 53 byte cell, including a header that helps determine the final destination of that cell, was adopted as the broadband integrated services digital network (B-ISDN) standard. While a great deal of work has progressed on ATM since the standard was adopted, there remains a camp that voices concerns as to the technical challenges that face deployment of ATM for certain services. In particular, concerns have been raised questioning the use of ATM networks to effectively route traffic that is constant-bit-rate (CBR) in nature and highly correlated. Voice and video services are of particular interest because of their potential economic markets. While it is almost certain that ATM, given enough time and resources, will prove its ability to handle these services, it behooves us to look for alternatives based on experience with existing telecommunications products. We present work completed in this area     

Priority queueing strategies and buffer allocation protocols fortraffic control at an ATM integrated broadband switching system

The problem of furnishing an asynchronous transfer mode (ATM) based broadband-ISDN (B-ISDN) with two bearer services supporting different grades of transfer quality is addressed. The focus is on priority bandwidth and buffer management in the ATM communications nodes (switches, multiplexers or concentrators, and expanders) in the context of a multichannel network architecture. Detailed queueing analyses and simulations and results are provided to evaluate the differentiation between traffic classes that can be achieved by different strategies. The implementation complexity of the different schemes is discussed. Various priority queueing strategies characterized mainly by different degrees of resource sharing and a general system model for performance evaluation are introduced. Performance comparisons and design tradeoffs are addressed     

Satellite ATM for broadband ISDN

This paper presents the development of satellite ATM for broadband ISDN based on the Research in Advanced Communications in Europe (RACE) CATALYST project. The purpose of the project is to develop an experimental ATM satellite link for the future B-ISDN services, particularly for the interconnections of the ATM testbeds which are in the form of broadband islands developed in Europe. Then initial ATM based B-ISDN can be introduced by interconnections of these broadband islands. An evolutionary approach has been adopted in the development of the ATM networks that the CATALYST project has developed the equipment to be able to interconnect the newly developed ATM testbeds as well as the existing networks such as DQDB, FDDI and Ethernet networks. In March 1994, the project carried out an experiment on the second demonstratoras the Laboratories of Alcatel Telespace in Nanteere near Paris to demonstrate the capability of the satellite ATM connections supporting data, voice, video and multimedia applications. This experiment provided a real system demonstration of satellite ATM for B-ISDN. In the light of the experiment, this paper presents the model and architecture of the ATM satellite equipment, studies the relevant issues and the impact of ATM-via-satellite on the applications and the protocols, and evaluates of satellite ATM based on some measured and simulated results.     

ATM traffic management in an LMDS wireless access network

We investigate the capacity of LMDS to support ATM services in the local loop. In particular, we evaluate the performance of a MAC protocol for this system when transporting voice and IP traffic using the VBR and GFR service categories of ATM, respectively. Our results show that the MAC protocol is well suited for voice traffic but in general lacks efficient bandwidth management mechanisms to support the more dynamic bandwidth requirements of IP traffic     

QoS and multipoint support for multimedia applications over the ATMABR service

Multimedia applications with stringent delay requirements are usually supported by the constant bit rate (CBR) or real-time variable bit rate (rt-VBR) service categories of ATM. This article shows that the available bit rate (ABR) service, which was originally designed for data, can also support multimedia applications under certain circumstances. Issues related to the design of proper ABR traffic management algorithms for such support are presented     

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.     

Bandwidth allocation and connection admission control in ATMnetworks

Asynchronous transfer mode (ATM) is the transmission format for almost all future communication networks, including broadband integrated services digital networks (B-ISDN). The key feature of ATM is its high flexibility in bandwidth allocation. Instead of reserving capacity for each connection, the bandwidth is allocated on demand. As a consequence, packets (called cells in ATM terminology) might be lost. To guarantee a given quality of service (QoS), some kind of control is needed to decide whether to accept or to reject an incoming connection. A connection is accepted only if the network has sufficient resources to achieve the QoS required by the user without affecting the QoS of the existing connections. In ATM networks, connection admission control (CAC) is responsible for this decision. It is a very complex function because the traffic may vary greatly and have poorly known characteristics. This paper describes CAC procedures proposed in the literature and discusses issues related to bandwidth allocation in ATM networks. It shows that CAC and statistical multiplexing are only needed for certain connections     

The MainStreetXpress core services node-a versatile ATM switcharchitecture for the full service network

Switching systems based on the ATM principle have outgrown the experimental stage, and are already used today in private and corporate networks, as well as in public wide area networks to provide regular service. ATM has the inherent ability to provide a common basis for transmission and switching functionality in both local and wide area networks. With the potential to support all services available today as well as those envisaged for the future, ATM holds a strong promise for network operators and end customers. To fully exploit this potential, ATM switch architectures are required which provide versatility and modularity in supporting services and protocols, independent scalability of data throughput and control performance over a wide range, and also reliability features adaptable to the respective application scenario. This paper describes in some detail how the MainStreetXpress core services node, which has evolved from the prototype described by Fischer et. al. (1991) to a mature central office ATM switch, addresses these issues and provides a future-proof architecture incorporating all of the features required in the B-ISDN era