Heinrich J. Stüttgen

Transport services for multimedia applications on broadband networks

Abstract A new class of computer network applications, called multimedia applications, is currently evolving. At the same time high speed networks such as FDDI, DQDB and B-ISDN are being developed. The question is, how can a multimedia application take best advantage of these high speed networks. The term multimedia applications, as used in this paper, refers to computer network applications with widely varying data traffic characteristics. In this paper an interface is outlined suitable for conveying the different application requirements to the communication subsystem, here called the transport system.

Network evolution and multimedia communication

The survey analyzes the communication requirements of distributed multimedia applications. To understand the ongoing evolution of networking, we must consider how current and new networking technologies support these requirements. In addition to the functional aspects, the survey investigates how the new technologies blend with existing infrastructures. It concludes with a brief discussion of the higher layer multimedia communication issues.

Implementation of an Internet video conferencing application over ATM

The paper describes a complete implementation of an Internet video conferencing application taking advantage of the quality-of-service (QoS) capabilities provided by ATM. RSVP has been used to exchange the QoS parameters among the communicating video conferencing applications. The RSVP QoS parameters are mapped to ATM parameters and dedicated VCs with the corresponding ATM parameters are established by the underlying classical IP over ATM implementation. These VCs provide the desired QoS from the ATM network to the application data flow. The implementation is based on existing components such as an Internet conferencing tool, a RSVP implementation, and a classical IP over ATM implementation. The paper presents the required modifications of all these components to support QoS communication and the adaptation for their integration.

A Linux Implementation of a Differentiated Services Router

The Internet Engineering Task Force (IETF) is currently working on the development of Differentiated Services (DiffServ). DiffServ seems to be a promising technology for next-generation IP networks supporting Quality-of-Services (QoS). Emerging applications such as IP telephony and time-critical business applications can benefit significantly from the DiffServ approach since the current Internet often can not provide the required QoS. This paper describes an implementation of Differentiated Services for Linux routers and end systems. The implementation is based on the Linux traffic control package and is, therefore, very flexible. It can be used in different network environments as first-hop, boundary or interior router for Differentiated Services. In addition to the implementation architecture, the paper describes performance results demonstrating the usefulness of the DiffServ concept in general and the implementation in particular.

Performance evaluation of a Linux DiffServ implementation

This paper aims to discuss the possibilities and the limitations of differentiated services (DiffServ) based on end-to-end performance measurement results obtained with a DiffServ implementation on Linux routers. The paper describes methods for end-to-end performance measurements of bandwidth, delay, and jitter for both TCP and UDP flow. The measurement results show that both per-hop-behaviours-expedited (EF) and assured forwarding (AF)-are able to provide a guaranteed bandwidth together with a very small delay and jitter even in a highly congested network as long as sufficient network resources are provisioned. The results further show that not only EF but also AF can be used to provide low delay services.

Transportdienste in Breitbandnetzen

Durch den Fortschritt im Bereich der Mikroelektronik sowie der Ubertragungs- und Vermittlungstechnik ist die Integration der Daten- und Telekommunikation nicht nur netzseitig, sondern auch im Bereich der Endsysteme und damit auch der verteilten Anwendungen moglich geworden. Durch die integrierte Verarbeitung und Ubertragung von Sprache, Text, Daten, Fest- und Bewegtbildern werden aber auch neuartige Anforderungen an die Funktionalitat und Dienstgute der transportorientierten Funktionen der unteren vier Schichten des OSI-Referenz- modells gestellt, die durch die heute existierende Standards nicht abgedeckt werden. Im folgenden werden daher die notwendigen Erweiterungen des Transportdienstes vorgestellt und diskutiert. Im einzelnen sind dies erweiterte Dienstguteparameter, ein neuartiger Request/Response- Dienst, die Gruppenkommunikation und die gemeinsame Verwaltung mehrerer Transportverbindungen durch ein Call Management.

Implementation of differentiated services over ATM

The paper describes the concept and the implementation of differentiated services over ATM. ATM components are being used in order to implement DiffServ traffic conditioning components such as shaping and policing. The implementation architecture based on a Linux router platform and some initial performance measurement results are presented.

An internetworking architecture for multimedia communication over heterogeneous networks

Distributed multimedia applications of the future will run on heterogeneous networks. Initially deployed on traditional LANs like Token Ring and FDDI there will be a long period of transition to ATM-based LANs that offer better support for continuous media traffic like video and audio. In parallel, public ATM services emerge that enable the wide-area interconnection of LANs. In this paper we identify the issues involved in the interconnection of heterogeneous networks for multimedia communication. We discuss the interaction of traffic management, signalling and data transmission protocols and present alternatives in the protocol architectures.

Layer4+ Supported Class of Service

Class of Service (CoS) support within the Internet is currently discussed and may become reality in the near future. Current applications usually lack the ability to articulate their service demands in order to make use these new services. Integrating support for such applications into the network is desirable and would allow these applications to coexist with future service-aware applications.

Die Internet-Architektur für integrierte Multimediakommunikation

Dr. rer. nat. Torsten Braun studierte Informatik an der Universität Karlsruhe. Nach seinem Diplom an der Fakultät für Informatik war er von 1990-1994 wissenschaftlicher Mitarbeiter am Institut für Telematik der Universität Karlsruhe, wo er 1993 promoviert wurde. Nach einem Forschungsaufenthalt am Institut National de Recherche en Informatique et en Automatique ( INRIA) in Sophia-Antipolis (Frankreich) von 1994-1995 ist er seit 1995 wissenschaftl icher Mitarbeiter in der Abteilung Breitband-Mult imedia Kommunikat ion des European Networking Center (ENC) der IBM in Heidelberg.