جنبه های سوئیچینگ تجزیه و تحلیل سیستم تحول قرن

Traffic Theory has accompanied the evolution from early switching systems to an omnipresent communication infrastructure through the last century. Targeting at the mathematical modelling of call attempts at first the main goal was the dimensioning of telephone infrastructure. Emerging new services, mobile communication environments and the integration of packet style communication links into by then well known switched circuit equipment has put new challenges to traffic theory. Still new interpretations and facets of the basic models are found and elaborated to make traffic theory useful for modern systems as the internet.

The institute of Electronic Systems and Switching, led by Prof. Dr.-Ing. Rudolf Schehrer, has accompanied and taken part of the evolution of communication systems throughout the last 3 decades. This paper comprises notes on milestones of this work. Early issues were concentrating on the design of computer based and decentralized switching systems that would compete against classical electro mechanical designs. The scientific results led on to the ISDN era in the late 1970’s, where service integration forced new strains of thought to complement the capacity oriented design of switching systems so far. The emerging internet in the early 1990’s and the simultaneous need of mobile access to communication resources added further challenges as packet stream multiplexting resulted in and contributed to ATM systems, providing a promising techology formulti service backbones. Modelling the data traffic itself instead of the utilization of trunks came into focus, while the interaction of signalling and transprort protocols for the sake of seamless mobility opened up complete new fields of research. The multitude of parameters, all showing different and partly long time correlated distributions became a severe challenge as the amount of data to be analyzed grew steadily in the recent years. Due to that, new approaches to handle the data of experiments and measurements of real traffic had to be devised. Received February 20, 2004. LS Elektronische Systeme und Vermittlungstechnik, Fakultät für Elektrotechnik und Informationstechnik, Universität Dortmund, 44221 Dortmund, Germany. web: www.esv.e-technik.uni-dortmund.de E-mail:scheher@esv.e-technik.uni-dortmund.de A snapshot of the current work at the institute shall highlight these activities. Section 2 and 3 depict the application of classical traffic theory to modern mobile switching systems for the case of hierarchical networks. Section 4 gives an overviewon a concept of “localisation” defined by a distance metric which is derived from a neighbourhood of information, targeting at a distribution of relevant information to a specific set of consumers. Section 5.2 finally highlights state of the art methods to deal with the problem of getting proper information for the models devised earlier out of huge amounts of data. In addition, concepts of visualizing network traffic are introduced.

Local information and its infrastructure was described in this section. The communication approach is very different to well-known point-to-point data transfer and its advantages must be proven in the future. Therefore work was started, to implement the discribed layers into the network simulator NS2 and into the netBSD-Kernel. At the end of this work a demonstrator will be ready to show the “real life” functionality as well as a simulation environment to emulate even big networks