Integrated Services Digital Research Articles

The effect of cut-through switching on the performance of buffered banyan networks

Abstract Fast packet switches based on banyan interconnection networks and their variations are being proposed for Broadband Integrated Services Digital Network (B-ISDN). Previous analyses on buffered banyan networks mainly assume the store-and-forward operation of the switching systems. In this paper we study the effect of cut-through switching on buffered banyan networks. Two types of buffered banyan networks are considered: those with the switching elements employing input buffers and those employing output buffers. We extend the analytical method of Theimer et al. to multibuffered banyan networks, and to buffered banyan networks with output buffering in the switching elements. We present the analyses of buffered banyan networks operating under cut-through switching. The results of these analyses confirm the simulation results, originally made by Bubenik and Turner, that cut-through switching in buffered banyan networks improves both throughput and delay performances.

North American Integrated Services Digital Network (ISDN) Users Forum (NIUF) - Gaithersburg, Md - June 22-25, 1993

North American Integrated Services Digital Network (ISDN) Users Forum (NIUF) - Gaithersburg, Md - June 22-25, 1993

A novel congestion control strategy in ATM networks

In order to guarantee a committed Quality of Service (QoS) to the users of a Broadband Integrated Services Digital Network (B-ISDN), preventive congestion control becomes critical, and is implemented through Call Acceptance Control (CAC), Usage Parameter Control (UPC), and Space Priority functions. Currently, Asynchronous Transfer Mode (ATM) cells are equipped with a 1-bit Cell Loss Priority (CLP) field, which can be used for service-oriented and/or UPC marking. This creates a conflict, since these two marking approaches may have contradicting objectives, and are designed to operate independently. Moreover, by admitting excessive cells as marked traffic, this group is allowed to grow uncontrollably, thereby jeopardizing the QoS committed to other (low priority) marked cells. This paper presents a solution to these problems based on a new 4-class priority strategy that unifies the two marking approaches, by utilizing a 2-bit CLP field. This is implemented by expanding the CLP field with the adjacent 1-bit RES field in the ATM cell header. A new variant of the “marking Leaky Bucket” UPC mechanism, called the Forgiving Leaky Bucket (FLB) will then be positioned at the Network-Node-Interface (NNI) of interworking ATM-based Broadband ISDN subnetworks. The FLB additionally has the power of un-marking ( forgiving) previously marked ATM cells, whenever the network conditions are appropriate. As a result, the end-to-end survival probability of a cell is improved significantly. Furthermore, “forgiving” corrects access-point bias, a phenomenon observed in interworked ATM subnetworks of different congestion conditions. Through simulations it is shown that this new priority strategy provides a significant improvement over the traditional marking Leaky Bucket UPC mechanism.

Multiplexers ΣD/D/1 with Service in Cyclic Order and Service in the Order of Arrival

AbstractIn future Broadband Integrated Services Digital Networks, information will be transferred in the form of small fixed sized data units called cells. Stations making use of constant bit rate services generate cells at regular intervals. The waiting times experienced by cells if such cell streams are multiplexed and the properties of the cell stream outgoing from the multiplexer are of high interest. They are analyzed here for time continuous, time slotted and time discrete operation, comparing service in cyclic order to service in the order of arrival. Results are given in closed form.

Operations process planning: A systems approach

The public telephone network is evolving rapidly from an embedded analog network to a digital network with a diverse capability for new services in a multi-media environment. Planning operations processes to effectively provision and maintain this ever-changing network is a challenge. This paper presents a systems approach for operations process planning that is a cost-effective alternative to a “trial-and-error” method for instituting change. This methodology enables a planner to gather a full understanding of existing processes and to test out the system effects of changes to the process. An Integrated Services Digital Network (ISDN) maintenance provisioning process is used to illustrate the methodology and how it would be useful to operations planners. Extensions of the use of this methodology to architect new processes for other new services and technologies will be discussed briefly.

Diffusion approximations for GI/M/ s queues with service interruptions

Two heavy traffic limit theorems are presented for a GI/M/ s queue with server vacations. Server vacations are governed by an exogenous process which at any time specifies the number of servers who are on vacation. The number of vacationing servers can effect in the service rate of the remaining servers still functioning. In one case the number of servers going on vacation remains fixed as the queue approaches heavy traffic; in the other case the number grows at the rate of convergence to heavy traffic. The first limit is a diffusion process that is a mixture of an Ornstein-Uhlenbeck process and a Brownian motion with negative drift. The infinitesimal parameters of this limiting diffusion are governed by the exogenous vacation process. The second limit is a jump-diffusion process whose diffusion is a mixture of an Ornstein-Uhlenbeck process and a Brownian motion, while the jumps are from the vacation process. The parameters of this process also are controlled by the vacation process. We propose diffusion approximations for such queueing models in heavy traffic and describe an application in Integrated Service Digital Network (ISDN) communications links.

ISDN Design for Global Markets

Integrated Services Digital Network (ISDN) promises end-to-end, high-speed digital connectivity in a multivendor environment. Over the past several years, applications — such as high-speed data transfer and telemarketing enhancements — have expanded, and the deployment of ISDN customer-premises equipment has increased. However, applications that are available in some countries are not available in others, in part, because standards for the ISDN primary-rate interface (PRI) and the deployment rates of this interface vary from country to country (and carrier to carrier). Thus, true global portability of the protocol is not feasible at this time. However, it is possible to design and develop a PRI implementation that aligns with these varying standards in a single software and hardware base. The implementation requires flexibility and leniency in handling certain protocol elements and may rely on system administration to allow explicit control over some country-specific options of the protocol. This paper reviews the differences found worldwide in the ISDN PRI standards, and describes the flexibility that can be designed into an ISDN PRI implementation to accommodate these inconsistencies.

Conference Report: NORTH AMERICAN INTEGRATED SERVICES DIGITAL NETWORK (ISDN) USERS' FORUM (NIUF) Gaithersburg, MD October 26-30, 1992.

Conference Report: NORTH AMERICAN INTEGRATED SERVICES DIGITAL NETWORK (ISDN) USERS' FORUM (NIUF) Gaithersburg, MD October 26-30, 1992.

Integrated Services Digital Networks (ISDN): six case study assessments of a commercial implementation

Abstract Integrated Services Digital Networks (ISDN) have recently move from the conceptual phase to the marketplace with a great deal of media attention. The purpose of this paper is to examine the experiences of six ISDN clients of the Southern Bell company in Atlanta, Georgia with a view to identifying the technological and organizational considerations involved in the promotion of integrated telecommunication services. The data were collected in a series of extensive interviews with the senior executives directly responsible for ISDN implementation in the six firms. Interviews were also conducted with the marketing group of the service provider. The results of our study indicate that while the implementation of ISDN has proceeded without any major glitches, the value added from the new service is still rather vague and mostly undocumented. Furthermore, a host of both technical and organizational issues will need to be resolved before the full benefit of ISDN is appreciated. A principal technical issue is that of customer premise equipment (CPE) compatability, and the major organizational issue is that of determining what new and/or existing applications should be facilitated by using ISDN. An appropriate tariff for ISDN is also an area requiring careful consideration.

Broadband‐ISDN: Personal Connections to Global Resources

Discusses the telecommunications infrastructure of the USA and issues surrounding its restructuring. Describes the role and impact of broadband Integrated Services Digital Network (ISDN) in applications development and the societal implications of this change. Points out that global development of broadband technologies makes personal access to multimedia applications possible and promotes new information‐sharing partnerships. Argues for an holistic, ethical approach to future development of ISDN.

ISDN Personal Video

Desktop personal video telephony has become an area of increased interest among telecommunications professionals. This interest has been spurred by the combination of increased availability and lower cost for the bandwidth required for video transmission, and significant advances in video compression technology. Although analog technology current supports video telephony, the Integrated Services Digital Network (ISDN) will increase the growth and development of video telecommunications.

A Multimedia Distance Learning Trial Using ISDN BRI

Distance Learning using multimedia communications can be conducted in a point-to-point or multipoint mode. Trials were conducted at California State University in Chico to assess the viability of using Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) for transmission of voice, data and video. A prototype multimedia bridge was developed for the multipoint trial based on Definity® telecommunications system technology.

特集 ディジタル伝送 ディジタル衛星放送用変調方式の検討

Digital modulation schemes for satellite broadcasting, such as ISDB (Integrated Services Digital Broadcasting), are investigated. The study must take into account the following conditions when using a 12 GHz band for digital broadcasting. The transmission scheme has to satisfy the criteria of WARC-BS. In addition, service availability must be compatible with conventional FM television services which are in use now. This is because simulcast services for digital and FM television will be necessary when digital broadcasting begins.This paper introduces a modulation sheme and suitable tansmission rate. This study used an ISDB transmission format which includes as error correction code comprising shortened difference set cyclic code (1016, 772). Characteristics of a broadcasting satellite transponder and mass-produced satellite receiver are simulated. Results show that ISDB service in a 12 GHz band is feasible using a 40 Mbps QPSK sheme. This is confirmed by simulations and indoor experiments.

Operational experience with DQDB MANs

In most developed countries, Metropolitan Area Networks (MAN) are being field tested (or it is planned to do so) as an intermediate, evolutionary step toward Broadband Integrated Services Digital Networks (B-ISDN). This paper deals with operational experience gained with the field introduction of MANs in Italy. Specifically, a DQDB-based MAN is described which is the basis of various implementations planned in major Italian cities. A field trial with the system started in October 1991 in Torino, the first example of a DQDB MAN installed for public service in Italy, and one of the first in Europe. The experience gained so far with this field trial is reported, together with the most significant test results obtained on running the system. Considerations on system evolution and a description of other similar MAN installations planned in the short-term in Italy are also discussed.

Evaluation of Broadband UNI Signaling Protocol Techniques

This paper compares several distinct approaches for providing user-network signaling in a Broadband Integrated Services Digital Network (B-ISDN). The protocols are examined against B-ISDN functional objectives and performance considerations. In addition, they are compared in terms of the ease of introducing new services, common UNI/NNI signaling, offering equal opportunity for service providers, and backward compatibility. The study concludes that the protocols may be made similar in terms of providing functionality. Each of the protocols examined provides advantages and disadvantages in the other areas compared.

Frame relay and SMDS services on a common ATM-based platform

The evolution to broadband networking in the world market has started, enabled by the evolution of the transmission infrastructure and new switching techniques. The market is being driven by the high-speed requirements imposed by the unprecedented penetration of LAN technology and associated high-speed applications as well as the integration of voice, data, image and video requirements. The rapid deployment of more reliable, often fiber-based, facilities migrating to the Synchronous Digital Hierarchy (SDH) and the introduction of switching techniques such as Frame Relay and Asynchronous Transfer Mode (ATM) make possible the introduction of networking capabilities to satisfy emerging requirements. Frame Relay services rely on a stream-lined protocol implementation that makes advantage of end-to-end error control strategies to simplify network processing and enable higher throughput and lower delay. Frame Relay services are being targeted at the 64 Kbps to E1 range. The Asynchronous Transfer Mode (ATM) has been accepted as the transport mechanism for the future Broadband Integrated Services Digital Network (B-ISDN). Metropolitan Area Networks (MANs), based on IEEE 802.6 ATM principles, represent the first commercial application of ATM technology. An early MAN service is the Switched Multimegabit Data Service (SMDS) 1 which has been specified to provide efficient high-speed data transport in the E1 to 34 Mbps range with future extensions to incorporate isochronous transport for the addition of constant-bit rate services such as voice and video services. Similar to SMDS, Connectionless Broadband Networking Services (CBDS) are being defined by ETSI for the European Market with input from the European SMDS Interest Group (ESIG). This paper presents an ATM-based architectural approach, as implemented in At&T's Broadband Networking System 2000 (BNS-2000), to provide Frame Relay as well as SMDS services on the sam platform. The BNS-2000 represents a growable and modular architecture that has been built to comply with international standards such as ANSI, CCITT and ETSI to support the emerging needs of the market.

ISDN - the telecommunications highway for Europe after 1992?

This article examines EC policies intended to promote the coordinated introduction of an Integrated Services Digital Network (ISDN) in all member countries by 1993. ISDN was originally supposed to be a new telecommunications network that would eventually replace the old telephone network. It is argued that the EC's ISDN activities are trapped between the attempt to liberalize the so far closed and fragmented European telecommunications markets on the one hand and the aim of building up a strong, independent European telecommunications industry and a Europe-wide telecommunications network on the other. At the moment ISDN deployment is far behind schedule and will not fulfil the Commission's expectations.

Global Teamwork: Developing International ISDN Capabilities for the 5ESS® Switch

Several geographically and culturally diverse partners within AT&T are working as a team to develop new capabilities for the 5ESS® switch in the international marketplace. Throughout this project, participants from organizations in AT&T Bell Laboratories in the United States and AT&T Network Systems International in The Netherlands and the United Kingdom have worked together using a common development process. This paper describes the global teamwork involved in the development of international Integrated Services Digital Network (ISDN) capabilities for the 5ESS switch.

Bridging remote connectionless LAN/MANs through connection oriented ATM networks

One major issue arising from the parallel development of communication networks using different operational principles and focusing in various applications, is the interconnection of users belonging to heterogeneous communication environments. This paper examines the interworking of existing LANs and MANs currently under development with the ATM (Asynchronous Transfer Mode) oriented B-ISDN (Broadband Integrated Services Digital Networks). The problem examined consists of the following parameters: (i) Alternative ways of connectionless (CL) data service provision by the connection oriented (CO) ATM network; and (ii) bridging protocols at the network access points. For (i), the CCITT scenarios are discussed and critically compared. Regarding (ii), a proposed bridge architecture is presented and its application to different LANs and MANs is investigated. The paper examines and critically compares the above cases, and discusses trade-offs in qualitative terms when different options are possible.

North American agreements on ISDN

The work of the North American Integrated Services Digital Network Users Forum (NIUF) is presented, and its relationship to the Accredited Standards Committee T1 and other standards bodies is discussed. The role of the NIUF within the ISDN arena is evident when considering the Federal Information Processing Standard (FIPS) for ISDN and the Transcontinental ISDN Project (TRIP), both of which are described. The relationship of the ISDN FIPS to the Government Open System Interconnection Profile (GOSIP) and the military standard on ISDN are also discussed. A comparison of NIUF agreements/ISDN standards and the Bellcore NI-1 specifications is presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>