Quality of Service over Specific Link Layers: state of the art report

The Integrated Services concept is proposed as an enhancement to the current Internet architecture, to provide a better Quality of Service (QoS) than that provided by the traditional Best-Effort service. The features of the Integrated Services are explained in this report. To support Integrated Services, certain requirements are posed on the underlying link layer. These requirements are studied by the Integrated Services over Specific Link Layers (ISSLL) IETF working group. The status of this ongoing research is reported in this document. To be more specific, the solutions to provide Integrated Services over ATM, IEEE 802 LAN technologies and low-bitrate links are evaluated in detail. The ISSLL working group has not yet studied the requirements, that are posed on the underlying link layer, when this link layer is wireless. Therefore, this state of the art report is extended with an identification of the requirements that are posed on the underlying wireless link, to provide differentiated Quality of Service

Electronic and photonic switching in the atm era

Broadband networks require high-capacity switches in order to properly manage large amounts of traffic fluxes. Electronic and photonic technologies are being used to achieve this objective both allowing different multiplexing and switching techniques. Focusing on the asynchronous transfer mode (ATM), the inherent different characteristics of electronics and photonics makes different architectures feasible. In this paper, different switching structures are described, several ATM switching architectures which have been recently implemented are presented and the implementation characteristics discussed. Three diverse points of view are given from the electronic research, the photonic research and the commercial switches. Although all the architectures where successfully tested, they should also follow different market requirements in order to be commercialised. The characteristics are presented and the architectures projected over them to evaluate their commercial capabilities.Peer ReviewedPostprint (published version

ACSys/RDN experiences with Telstra’s experimental broadband network, second progress report

This report addresses three issues relevant to DHPC network infrastructure requirements:. · Technically, what we can currently achieve with the EBN? · What are desirable qualities in future ATM networks? · What further development of the EBN would we like to see for other applications? In writing this report, we will briefly describe the EBN ATM experience of ACSys’ Distributed High Performance Computing Project and Digital Media Libraries project, explain some of the technology and networking issues we have dealt with and summarise what we have learned. We have also included some background material on the EBN and ATM networks in general

An Integrated Network Architecture for a High Speed Distributed Multimedia System.

Computer communication demands for higher bandwidth and smaller delays are increasing rapidly as the march into the twenty-first century gains momentum. These demands are generated by visualization applications which model complex real time phenomena in visual form, electronic document imaging and manipulation, concurrent engineering, on-line databases and multimedia applications which integrate audio, video and data. The convergence of the computer and video worlds is leading to the emergence of a distributed multimedia environment. This research investigates an integrated approach in the design of a high speed computer-video local area network for a distributed multimedia environment. The initial step in providing multimedia services over computer networks is to ensure bandwidth availability for these services. The bandwidth needs based on traffic generated in a distributed multimedia environment is computationally characterized by a model. This model is applied to the real-time problem of designing a backbone for a distributed multimedia environment at the NASA Classroom of the Future Program. The network incorporates legacy LANs and the latest high speed switching technologies. Performance studies have been conducted with different network topologies for various multimedia application scenarios to establish benchmarks for the operation of the network. In these performance studies it has been observed that network topologies play an important role in ensuring that sufficient bandwidth is available for multimedia traffic. After the implementation of the network and the performance studies, it was found that for true quality of service guarantees, some modifications will have to be made in the multimedia operating systems used in client workstations. These modifications would gather knowledge of the channel between source and destination and reserve resources for multimedia communication based on specified requirements. A scheme for reserving resources in a network consisting legacy LAN and ATM is presented to guarantee quality of service for multimedia applications

On QoS Provisioning in ATM Networks

ATM is representative of the connection-oriented resource provisioning class of protocols. An ATM network isexpected to provide end-to-end QoS guarantees to connections in the form of bounds on delays, errors and/or losses.Performance management involves measurement of QoS parameters, and application of control measures (if required)to improve the QoS provided to connections, or to improve the resource utilization at switches. QoS provisioning is veryimportant for real-time connections in which losses are irrecoverable and delays cause interruptions in service. Mostscheduling disciplines provide static allocation of resources at connection setup time. End-to-end bounds are obtainablefor some schedulers, however these are precluded for heterogeneously composed networks. The resource allocation doesnot adapt to the QoS provided to connections in real-time. In addition, mechanisms to measure the QoS of a connectionin real-time are scarce.A novel framework for QoS management is proposed in this paper to provide QoS guarantees to real-time connections.It comprises of in-service QoS monitoring mechanisms, a hierarchical scheduling algorithm based on dynamicpriorities that are adaptive to measurements, and methods to tune the schedulers at individual nodes based on the endto-end measurements

Analytical models for the multiplexing of worst case traffic sources and their application to ATM traffic control.

Postprint (published version