Performance Evaluation and Modelling of Networks
Monday, April 21st 2008, 15:30-16:30, SE III
Professor Anthony E. KrzesinskiDepartment of Computer Science |
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It is a great pleasure for us to announce a talk from Prof. Anthony E. Krzesinski from the University of Stellenbosch, South Africa.
Abstract: Mapping the African Internet
The decentralized nature of the Internet and the complexity and diversity of its infrastructures, owners and operators together with the market-driven incentives for providers to obscure their network infrastructures have made comprehensive knowledge of Internet connectivity difficult to obtain.
The goal of this project is to determine accurately and anonymously where Internet resources are logically and geographically located in the African Internet. The resources include autonomous systems (ASs), peering relationships, Internet service provider (ISP) points of presence (POPs), routers and links.
This talk will describe the methods used to generate maps of the African Internet both at the router level and at the autonomous system (AS) level. The traceroute utility was used to collect router level information on the Internet. BGP routing tables were used to collect
AS information.
We developed software to automate the sending of traceroute probes to selected IP addresses, to store the information produced by the traceroute data and to transform the data into adjacency matrices. The adjacency matrices, together with geographical data concerning the
location of the routers, were used to draw various maps showing the Internet topology.
Abstract: A Distributed Scheme for Responsive Network Engineering
Optimal bandwidth utilisation together with resilience and recovery from failure are two key drivers for Traffic Engineering (TE). Most IGP routing protocols deployed in the Internet and their TE extensions are concerned either with optimality or with resilience. This leads to a duplication of routing protocols and algorithms where each of these objectives (optimality, resilience) is addressed by its own protocol or algorithm. The interactions among these protocols introduce additional complexities which do not necessarily translate into equivalent performance gains.
We have developed a unified Network Resource Controller which combines these two objectives. At random time instants the NRC computes bandwidth prices which are used in an automated scheme to dynamically adjust the bandwidths of the network paths in response to the traffic and network equipment conditions. The NRC works without centralised control and thus scales to large networks: rather than using TE to move network flows to where the network bandwidth is located, the NRC uses Network Engineering (NE) to move network bandwidth to where the network flows are located.
We next present an efficient heuristic to find diversely routed backup paths and to provision the network links with the least amount of backup (spare) bandwidth in order to be able to deploy equivalent recovery paths for any failure scenario which leaves the network connected.
Simulation results are presented which show that the reallocation scheme provides prompt bandwidth provisioning both for random traffic fluctuations during normal operating conditions, and when provisioning recovery routes in the event of network failure.
Background
Anthony Krzesinski obtained the MSc from the University of Cape Town and the PhD from Cambridge University, England. He is a Professor of Computer Science at the University of Stellenbosch. His research interests centre on the performance evaluation of telecommunication networks.
More information is available at http://www.cs.sun.ac.za/~aek1/.
