Abstract-

Abstract-

No abstract

No abstract

We consider the problem of computing orthogonal drawings and quasi-upward drawings with vertices of prescribed size. For both types of drawings we present algorithms based on network flow techniques and show that the produced drawings are optimal within a wide class. Further, we present the results of an experimentation conducted on the algorithms that we propose for orthogonal drawings. The experiments show the effectiveness of the approach.

Network emulators are software environments that closely reproduce the functionalities and the behavior of real world networks. In this paper we describe Netkit, a freely available lightweight network emulator based on User-Mode Linux. Netkit allows users to experiment with a large number of network technologies and provides tools for a straightforward setup of complex network scenarios that can be easily distributed via email or published on the Web. Netkit also comes with a set of ready to use experiences, accompanied by lecture slides, that enable users to immediately experiment with specific case studies. Our system has proved itself to be helpful in testing the configuration of ISP-scale real world networks and is profitably used within University level networking courses. We provide a detailed comparison against other competing solutions and experimental measures about the scalability of the system.

Abstract. In this paper we study the clustered graphs whose underlying graph is a cycle. This is a simple family of clustered graphs that are "highly non connected". We start by studying 3-cluster cycles, that are clustered graphs such that the underlying graph is a simple cycle and there are three clusters all at the same level. We show that in this case testing the c-planarity can be done efficiently and give an efficient drawing algorithm. Also, we characterize 3-cluster cycles in terms of formal grammars. Finally, we generalize the results on 3-cluster cycles considering clustered graphs that at each level of the inclusion tree have a cycle structure. Even in this case we show efficient c-planarity testing and drawing algorithms.

In this paper we describe the architecture and the visual interface of BGPlay, an on-line service for the visualization of the behavior and of the instabilities of Internet routing at the autonomous system level.A graph showing only the connections among autonomous systems is not enough to convey all the information needed to fully understand routing and its changes. BGPlay uses specifically tailored techniques and algorithms to display the state of routing at specific points in time and to animate its changes. The system obtains routing data from well known on-line archives of routing information which are constantly kept up-todate.