ERCIM News No.37 - April 1999

Activities at SICS's Computer and Network Architecture Laboratory

by Bengt Ahlgren

The focus of the Computer and Network Architecture (CNA) laboratory is in the networking technology and the computing platform for advanced distributed applications on the Internet. The networking technology ranges from the design of hardware for IP routers over core Internet protocols in the network and transport layers to how distributed applications use the network service.

The CNA lab participated in the EU Esprit LTR project HIPPARCH together with researchers from INRIA Sophia-Antipolis, University College London, Uppsala University, Dassault Electronique (now part of Thompson-CSF) and University of Technology, Sydney. The project was finished at the end of August 1998 with excellent reviews. The project therefore received additional funding for exploiting the results further.

In HIPPARCH we have been investigating novel architectures for high performance communication protocols based on the Application Level Framing (ALF) and Integrated Layer Processing (ILP) concepts. The project also adopted the notion of “network conscious applications”, that is, applications that are aware of varying network conditions and that adapt in one way or another to these conditions in order to optimize application performance. This notion is based on the belief that it is only the application itself that can make the best adaptation decision, for example, change audio encoding algorithm.

The results from the project include a protocol compiler supporting the development of ALF based applications, control algorithms for network consciousness, a multicast based reliable distribution protocol, a QoS model for network conscious applications and a network bandwidth probing tool.

We are also participating in the EU Esprit project Pegasus II. The other partners are University of Cambridge, University of Twente, University of Glasgow and Citrix Ltd (Cambridge, UK, formerly APM Ltd). The Pegasus II project develops an operating system, Nemesis, which is a generic platform for multimedia applications featuring effective user control over resource allocation policy.

A mobile ad-hoc network, or “MANET”, is a self-configuring multihop wireless packet network, where all nodes participate in forwarding packets to their destinations. All nodes are also mobile, and thus free to move arbitrarily. Ad-hoc networking is a hot research area in the area of mobile communication. The research issues we are working on in this area are power management, routing protocols and addressing to provide Internet connectivity to ad-hoc networks.

In a previous project we have developed a dimensioning model for IP telephony. We are continuing this work with simulations and measurements in experimental networks to validate the model and to evaluate if an IP network with differentiated services can provide the necessary network quality of service for telephony.

For more information on the Computer and Network Architecture Laboratory, see

Please contact:

Bengt Ahlgren - SICS
Tel: +46 8 633 1562

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