ATM-layer OAM: principles and open issues [B-ISDN]

The principles of operation and maintenance (OAM) for broadband ISDN access, as well as some general OAM rules for an asynchronous transfer mode (ATM) network, are discussed. Standardization of the OAM functions and mechanisms for the ATM layer, which is based primarily on CCITT Recommendations, is considered. Issues regarding OAM flow at the ATM layer are examined. It is seen that although references can be made both to basic and primary rate ISDN, new solutions are necessary for the OAM of B-ISDN. Issues requiring further study are identified     

A guide to data communications: B-ISDN and how it works

The capabilities of the emerging broadband integrated services digital network (B-ISDN) are examined. Fundamental differences between broadband and narrowband ISDN are identified. The basics of asynchronous transfer mode (ATM), the switching technique used by BISDN networks, are discussed. Channel identification, generic flow control, using ATM, and connectionless service are considered. The first services expected to make use of ATM are briefly described     

Layered ATM systems and architectural concepts for subscribers'premises networks

The authors review the essential elements of the ATM (asynchronous transfer mode) technique and presents a framework for the definition of ATM, based on the ISDN (integrated-services digital network) protocol reference model. A layered functional model of an ATM open system is presented and the relation with existing packet techniques is studied. The use of ATM in the subscribers' premises network (SPN) is analyzed. A two-tier SPN architecture is proposed covering both residential and business environments, in line with the modeling principles outlined. The merits of this architecture in the field of standardization are emphasized. Some implementation issues and the relation with the reference configuration are discussed     

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 practical dimensioning method for ATM systems

In this paper, a simplified practical method for dimensioning asynchronous transfer mode (ATM) systems is proposed. Packet switching services are classified into two categories: connection-oriented packet switching (COPS) with quality of service (QoS) guaranteed and connection-less packet switching (CLPS) on a best effort basis. A new control scheme is proposed for maintaining the cell-level QoS requirement for the COPS even in overload conditions. A dimensioning method is also proposed for the system where the COPS is served with nonpreemptive priority over the CLPS. The methods proposed are expected to contribute to the realization of robust and economical ATM systems     

多媒体通信与ATM传输网络技术

本文首先介绍了传输视频、音频、图象、图形、文本、动画等媒体信息对网络的要求。然后讨论了ＡＴＭ中分组交换、面向连接技术以及ＡＴＭ对多媒体通信的支持，充分证实ＡＴＭ传输网络技术是目前多媒体通信中最理想的网络技术。     

B-ISDN architecture and protocol

The authors discuss the architecture and protocol for broadband ISDN (B-ISDN) based on the CCITT standards. The discussion attempts to address the general concept of B-ISDN architecture and protocol and, whenever possible, present alternatives and the rationale for decisions in the selection of the protocol. B-ISDN is presented as a network evolution, and the impact of the asynchronous transfer mode (ATM) on the network is described. The role of virtual channel and virtual path in B-ISDN is discussed. The B-ISDN protocol structure and lower layer functions comprising the physical, ATM, and adaptation layers are presented, and the tentative trends of signaling and traffic control for the B-ISDN are delineated     

Lightwave subscriber loop systems toward broad-band ISDN

The state-of-the-art of lightwave subscriber loop systems is reviewed. An approach is described for deriving an architecture for subscriber loop systems that can accommodate technological trends in broadband ISDN such as asynchronous transfer mode (ATM) and synchronous digital networks. Key component technology is discussed, namely, optical fibers and cables, splicing and connectors, and switching     

Fast restoration of ATM networks

Asynchronous transfer mode (ATM) is now well recognized as the fundamental switching and multiplexing technique for future broadband ISDN. As these networks will be increasingly relied upon for providing a multitude of integrated voice, data, and video services, network reliability is a key concern. There are several intrinsic features of ATM networks that could potentially be exploited to provide improved restoration techniques, beyond those established for synchronous transfer mode (STM) networks, such as digital cross-connect restoration or self-healing rings. These features include ATM cell level error detection, inherent rate adaptation and nonhierarchical multiplexing. The authors explore the use of these features in developing fast restoration strategies for ATM networks. In particular, they address: (1) ATM error detection capabilities for enhanced failure detection, (2) network rerouting strategies, (3) spare capacity allocation, and (4) network control architecture and related implementation aspects. Their findings suggest that fast network span failure detection and bandwidth-efficient rerouting capabilities can be combined to develop restoration strategies for ATM networks with significantly greater performance-cost ratios when compared to existing STM network restoration strategies     

Asynchronous transfer mode or synchronous transfer mode or both

Some of the problem areas attendant upon the asynchronous transfer mode (ATM) concept are addressed. Concern is chiefly with the use of small, fixed-length packets and the issue of congestion control. It is argued that broadband ISDN services should not be tied down to ATM as presently standardized, because ATM has several problems when embedded in a wide area network with diverse services     

Designing a practical ATM LAN

The adaptor cards and driver software for workstations and local asynchronous transfer mode (ATM) switches and switch control software used in an ATM local area network (LAN) system are discussed. It is shown that the ATM hardware and software components together provide services that are essential for ATM to be considered a realistic alternative to current shared-media LANs. These services include: completely transparent support for the TCP/IP protocol suite, an application programming interface for full access to the underlying ATM capabilities, support for AAL5, AAL3/4, and the null AAL, both connection-oriented and connectionless service, dynamic connection establishment or switched virtual circuits, resource reservation of guaranteed bandwidth and quality of service, full-bandwidth multicast and broadcast, virtual path and channel routing among multiple switches, automatic configuration and failure recovery, dynamic address assignment and internetwork address resolution, and network management via the simple network management protocol (SNMP)     

CITT E.700 recommendation series-a framework for trafficengineering of ISDN

Traffic engineering of ISDN (integrated services digital network) has become a key area of CCITT recommendations since 1985. The authors report on the first recommendations formalized in a dedicated series on ISDN traffic engineering, the CCITT E.700 series of recommendations. The authors also report on the ongoing work towards an extension of the series to cover integration of mobile services into ISDN, the E.750 series. Future directions related to such emerging issues as intelligent network services and broadband-ISDN/ATM (asynchronous transfer mode) are also reviewed     

Performance management issues of currently operated ATM enterprisenetworks

The author proposes a solution for the allocation and balancing of resources to maximize available bandwidth shared among corporate users. Currently established broadband virtual private networks (BVPNs) based on asynchronous transfer mode (ATM) technology comprise ATM cross-connects (ATM-CCs) and a lot of intelligent customer premises equipment (CPE). The CPE, an intelligent ATM service switcher or ATM multiplexer, enables the corporate user to connect routers, private branch exchanges (PBXs), or codecs onto the ATM network. One fundamental characteristic of CPE is that it is capable of accumulating asynchronous and synchronous traffic which may belong to different corporate users' sites. A typical example given of a BVPN configuration serving two corporate network users with four user sites each. In general, each user site needs to exchange asynchronous (connectionless) data streams for the inter-local area network (LAN) communication and synchronous (connection-oriented) data streams with constant bit rates for video/voice communication. The configuration and the performance aspects of inter-LAN communications employing a connectionless server (CLS) are discussed. The bandwidth allocation aspects of the BVPN having to convey synchronous and asynchronous traffic in an ATM environment without a CLS are discussed, including the bandwidth allocation algorithm. The important characteristics of the proposed algorithm is also summarised     

Asynchronous transfer mode security

It is envisioned that asynchronous transfer mode (ATM) will provide scalable and high-performance application-independent security services. The ATM Forum Security Working Group is currently developing its phase one security specification, which defines a number of security services for the ATM user plane and control plane. In addition, mechanisms for carrying security-related messages and required security infrastructure mechanisms are also being defined. These mechanisms will allow an organization to build an ATM network which not only meets its performance objectives, but also its information protection requirements as specified in its site security policy. This article provides an overview of ATM security as specified by the ATM Forum Security Working Group. First, the ATM user and control planes' security services and mechanisms are described. Then the security messaging mechanisms at connection establishment and during the connection lifetime phases are discussed     

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     

Efficient use of protocol stacks for LAN/MAN-ATM interworking

Connectionless (CL) services as already developed in LANs, have to interwork with emerging asynchronous transfer mode (ATM) connection-oriented (CO) networks. MANs are a significant evolutionary step and CO MANs, in particular, constitute a technically appealing method to integrate both environments and provide shared medium access for all services. The functions required for enhancing distributed-queue dual-bus (DQDB) MANs with CO services in a way compatible with ATM are described. Within the integrating framework of B-ISDN, the practically useful scenarios for interworking LANs, CO and CL MANs, and ATM are investigated and classified in order to exploit the advantages of an efficient protocol relay utilizing the resources of the lowest possible layer. This is aimed at assisting interworking unit (IWU) designers and implementors to decide on key options in this versatile and evolving environment. The CO DQDB case emerges as the most advantageous development in terms of interworking simplicity and robustness     

Technical concepts in broadband ATM

The asynchronous transfer mode (ATM) approach to connecting subscribers to the broadband packet network, is expected to bring an appropriate solution for a future public network. The prerequisites of the broadband network, the characteristics of the ATM technique as well as possible ATM network equipment are described here. Envisaged solutions to the basic problems being posed are discussed.     

A scalable ATM switching system architecture

The architecture of an asynchronous transfer mode (ATM) switching system for prototype applications is presented. The general concept to upgrade the existing ISDN switch with an ATM module is introduced, and the building blocks of this ATM module are described in detail. Switching of ATM cells is performed in a single application-specific integrated circuit (ASIC). ASICs can be cascaded to form large switching modules. Peripheral modules interface the ATM switch to external transmission systems and perform all ATM-related functions, including means for redundancy of the switching network. The redundancy scheme tolerates single failures without affecting the user information. A switching network architecture is shown to be capable of fulfilling varying demands in terms of the number of ports for ATM switches and cross connects, concentrators, and multiplexers     

ATM local area networks

LAN emulation offers a best-effort, connectionless, packet transfer service at the MAC sublayer, implemented on top of a connection-oriented ATM network LAN emulation using switched virtual connections requires address resolution to locate the destination end station followed by connection establishment to the resulting ATM address. Address resolution may be implemented by a broadcast technique or by an address server. The broadcast method is the simplest for small networks but a combination of both is probably better. The use of the MAC address to identify an end station, with dynamic binding to its current physical location in the ATM network, allows the ATM LAN segment to be viewed as a virtual LAN. The virtual LAN model permits end stations to move and change physical location while maintaining connection to the same ATM LAN segment. This greatly simplifies the management of large data networks     

On self-similar traffic in ATM queues: definitions, overflowprobability bound, and cell delay distribution

Recent traffic measurements in corporate local-area networks (LANs), variable-bit-rate video sources, ISDN control-channels, and other communication systems, have indicated traffic behaviour of self-similar nature. This paper first discusses some definitions and properties of (second-order) self-similarity and gives simpler criteria for it. It then gives a model of self-similar traffic suitable for queuing system analysis of an asynchronous transfer mode (ATM) queue. A lower bound to the overflow probability of a finite ATM buffer is obtained, as also a lower bound to the cell loss probability. Finally, the stationary distribution of the cell delay in an infinite ATM buffer is obtained