Papers by Giuseppe DI BATTISTA
Discrete Mathematics, 2005
Consider a planar drawing \({\it \Gamma}\) of a planar graph G such that the vertices are drawn a... more Consider a planar drawing \({\it \Gamma}\) of a planar graph G such that the vertices are drawn as small circles and the edges are drawn as thin strips. Consider a cycle c of G. Is it possible to draw c as a non-intersecting closed curve inside \({\it \Gamma}\) , following the circles that correspond in \({\it \Gamma}\) to the vertices of c and the strips that connect them? We show that this test can be done in polynomial time and study this problem in the framework of clustered planarity for highly non-connected clustered graphs.
Journal of Graph Algorithms and Applications, 2000
We present a method for constructing orthogonal drawings of graphs of maximum degree six in three... more We present a method for constructing orthogonal drawings of graphs of maximum degree six in three dimensions. The method is based on generating the final drawing through a sequence of steps, starting from a "degenerate" drawing. At each step the drawing "splits" into two pieces and finds a structure more similar to its final version. Also, we test the effectiveness of our approach by performing an experimental comparison with several existing algorithms.
We investigate the problem of computing the types of the relationships between Internet Autonomou... more We investigate the problem of computing the types of the relationships between Internet Autonomous Systems. We refer to the model introduced in [1], [2] that bases the discovery of such relationships on the analysis of the AS paths extracted from the BGP routing tables. We characterize the time complexity of the above problem, showing both NP-completeness results and efficient algorithms for solving specific cases. Motivated by the hardness of the general problem, we propose heuristics based on a novel paradigm and show their effectiveness against publicly available data sets. The experiments put in evidence that our heuristics performs significantly better than state of the art heuristics.
Discrete Mathematics, 2005
Consider a planar drawing \({\it \Gamma}\) of a planar graph G such that the vertices are drawn a... more Consider a planar drawing \({\it \Gamma}\) of a planar graph G such that the vertices are drawn as small circles and the edges are drawn as thin strips. Consider a cycle c of G. Is it possible to draw c as a non-intersecting closed curve inside \({\it \Gamma}\) , following the circles that correspond in \({\it \Gamma}\) to the vertices of c and the strips that connect them? We show that this test can be done in polynomial time and study this problem in the framework of clustered planarity for highly non-connected clustered graphs.
Journal of Graph Algorithms and Applications, 2005
In this paper we describe the architecture and the visual interface of BGPlay, an on-line service... more 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.
Journal of Graph Algorithms and Applications, 2000
We present a method for constructing orthogonal drawings of graphs of maximum degree six in three... more We present a method for constructing orthogonal drawings of graphs of maximum degree six in three dimensions. The method is based on generating the final drawing through a sequence of steps, starting from a "degenerate" drawing. At each step the drawing "splits" into two pieces and finds a structure more similar to its final version. Also, we test the effectiveness of our approach by performing an experimental comparison with several existing algorithms.
Gdb, per essere stato il relatore. Titto, per essere stato un santo in generale. Gabriele, la cui... more Gdb, per essere stato il relatore. Titto, per essere stato un santo in generale. Gabriele, la cui trattazione di IPv6 mi ha più volte ispirato. Fabio, Laura, Marco e Giorgio, per avermi iniziato al magico mondo di L A T E X. Mauro Tortonesi, per avermi suggerito il metodo DNS. Stéfano e Giovannone, per avermi detto: "Inizia!". La mia famiglia, per avermi reso la vita facile. Teresa, per la sua meravigliosa cucina. Alessandra, per essermi stata vicino. Maurizio Goretti, Paolo Cursi, Bruno Ciscato, e Gabriella Paolini, che mi hanno dato gli strumenti per lavorare. . . . e, naturalmente, tutti quelli che mi sono dimenticato.
We investigate the problem of computing the types of the relationships between Internet Autonomou... more We investigate the problem of computing the types of the relationships between Internet Autonomous Systems. We refer to the model introduced in [1], [2] that bases the discovery of such relationships on the analysis of the AS paths extracted from the BGP routing tables. We characterize the time complexity of the above problem, showing both NP-completeness results and efficient algorithms for solving specific cases. Motivated by the hardness of the general problem, we propose heuristics based on a novel paradigm and show their effectiveness against publicly available data sets. The experiments put in evidence that our heuristics performs significantly better than state of the art heuristics.
In this paper we give a new description of the planarity testing and embedding algorithm presente... more In this paper we give a new description of the planarity testing and embedding algorithm presented by Boyer and Myrvold [2], providing, in our opinion, new insights on the combinatorial foundations of the algorithm. Especially, we give a detailed illustration of a fundamental phase of the algorithm, called walk-up, which was only succinctly illustrated in [2]. Also, we present an implementation of the algorithm and extensively test its efficiency against the most popular implementations of planarity testing algorithms. Further, as a side effect of the test activity, we propose a general overview of the state of the art (restricted to efficiency issues) of the planarity testing and embedding field.
Journal of Graph Algorithms and Applications, 2005
In this paper we describe the architecture and the visual interface of BGPlay, an on-line service... more 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.
IEEE Transactions on Network and Service Management, 2004
Tunnels are widely used to improve security and to expand networks without having to deploy nativ... more Tunnels are widely used to improve security and to expand networks without having to deploy native infrastructure. They play an important role in the migration to IPv6, which relies on IPv6-in-IPv4 tunnels where native connectivity is not available; however, tunnels offer lower performance and are less reliable than native links. In this paper we introduce a number of techniques to detect, and collect information about, IPv6-in-IPv4 tunnels, and show how a known tunnel can be used as a "vantage point" to launch third-party tunnel-discovery explorations, scaling up the discovery process. We describe our Tunneltrace tool, which implements the proposed techniques, and validate them by means of a wide experimentation on the 6bone tunneled network, on native networks in Italy, the Netherlands, and Japan, and through the test boxes deployed worldwide by the RIPE NCC as part of the Test Traffic Measurements Service. We assess to what extent 6bone registry information is coherent with the actual network topology, and we provide the first experimental results on the current distribution of IPv6-in-IPv4 tunnels in the Internet, showing that even "native" networks reach more than 60% of all IPv6 prefixes through tunnels. Furthermore, we provide historical data on the migration to native IPv6, showing that the impact of tunnels in the IPv6 Internet did not significantly decrease over a 6-month period. Finally, we briefly touch on the security issues posed by IPv6-in-IPv4 tunnels, discussing possible threats and countermeasures.
Gdb, per essere stato il relatore. Titto, per essere stato un santo in generale. Gabriele, la cui... more Gdb, per essere stato il relatore. Titto, per essere stato un santo in generale. Gabriele, la cui trattazione di IPv6 mi ha più volte ispirato. Fabio, Laura, Marco e Giorgio, per avermi iniziato al magico mondo di L A T E X. Mauro Tortonesi, per avermi suggerito il metodo DNS. Stéfano e Giovannone, per avermi detto: "Inizia!". La mia famiglia, per avermi reso la vita facile. Teresa, per la sua meravigliosa cucina. Alessandra, per essermi stata vicino. Maurizio Goretti, Paolo Cursi, Bruno Ciscato, e Gabriella Paolini, che mi hanno dato gli strumenti per lavorare. . . . e, naturalmente, tutti quelli che mi sono dimenticato.
Journal of Graph Algorithms and Applications, 2004
In this paper we study simple families of clustered graphs that are highly unconnected. We start ... more In this paper we study simple families of clustered graphs that are highly unconnected. We start by studying 3-cluster cycles, which 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 have a cycle structure at each level of the inclusion tree. We present efficient c-planarity testing and drawing algorithms also for this case.
In this paper we give a new description of the planarity testing and embedding algorithm presente... more In this paper we give a new description of the planarity testing and embedding algorithm presented by Boyer and Myrvold [2], providing, in our opinion, new insights on the combinatorial foundations of the algorithm. Especially, we give a detailed illustration of a fundamental phase of the algorithm, called walk-up, which was only succinctly illustrated in [2]. Also, we present an implementation of the algorithm and extensively test its efficiency against the most popular implementations of planarity testing algorithms. Further, as a side effect of the test activity, we propose a general overview of the state of the art (restricted to efficiency issues) of the planarity testing and embedding field.
IEEE/ACM Transactions on Networking, 2007
We investigate the problem of computing the types of the relationships between Internet Autonomou... more We investigate the problem of computing the types of the relationships between Internet Autonomous Systems. We refer to the model introduced by Gao (IEEE/ACM Transactions on Networking, 9(6):733-645, 2001) and Subramanian et al. (IEEE Infocom, 2002) that bases the discovery of such relationships on the analysis of the AS paths extracted from the BGP routing tables. We characterize the time complexity of the above problem, showing both NP -completeness results and efficient algorithms for solving specific cases. Motivated by the hardness of the general problem, we propose approximation algorithms and heuristics based on a novel paradigm and show their effectiveness against publicly available data sets. The experiments provide evidence that our algorithms perform significantly better than state-of-the-art heuristics.
IEEE Transactions on Network and Service Management, 2004
Tunnels are widely used to improve security and to expand networks without having to deploy nativ... more Tunnels are widely used to improve security and to expand networks without having to deploy native infrastructure. They play an important role in the migration to IPv6, which relies on IPv6-in-IPv4 tunnels where native connectivity is not available; however, tunnels offer lower performance and are less reliable than native links. In this paper we introduce a number of techniques to detect, and collect information about, IPv6-in-IPv4 tunnels, and show how a known tunnel can be used as a "vantage point" to launch third-party tunnel-discovery explorations, scaling up the discovery process. We describe our Tunneltrace tool, which implements the proposed techniques, and validate them by means of a wide experimentation on the 6bone tunneled network, on native networks in Italy, the Netherlands, and Japan, and through the test boxes deployed worldwide by the RIPE NCC as part of the Test Traffic Measurements Service. We assess to what extent 6bone registry information is coherent with the actual network topology, and we provide the first experimental results on the current distribution of IPv6-in-IPv4 tunnels in the Internet, showing that even "native" networks reach more than 60% of all IPv6 prefixes through tunnels. Furthermore, we provide historical data on the migration to native IPv6, showing that the impact of tunnels in the IPv6 Internet did not significantly decrease over a 6-month period. Finally, we briefly touch on the security issues posed by IPv6-in-IPv4 tunnels, discussing possible threats and countermeasures.
Journal of Graph Algorithms and Applications, 2004
In this paper we study simple families of clustered graphs that are highly unconnected. We start ... more In this paper we study simple families of clustered graphs that are highly unconnected. We start by studying 3-cluster cycles, which 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 have a cycle structure at each level of the inclusion tree. We present efficient c-planarity testing and drawing algorithms also for this case.
IEEE/ACM Transactions on Networking, 2007
We investigate the problem of computing the types of the relationships between Internet Autonomou... more We investigate the problem of computing the types of the relationships between Internet Autonomous Systems. We refer to the model introduced by Gao (IEEE/ACM Transactions on Networking, 9(6):733-645, 2001) and Subramanian et al. (IEEE Infocom, 2002) that bases the discovery of such relationships on the analysis of the AS paths extracted from the BGP routing tables. We characterize the time complexity of the above problem, showing both NP -completeness results and efficient algorithms for solving specific cases. Motivated by the hardness of the general problem, we propose approximation algorithms and heuristics based on a novel paradigm and show their effectiveness against publicly available data sets. The experiments provide evidence that our algorithms perform significantly better than state-of-the-art heuristics.
Discrete Mathematics, 2005
Consider a planar drawing \({\it \Gamma}\) of a planar graph G such that the vertices are drawn a... more Consider a planar drawing \({\it \Gamma}\) of a planar graph G such that the vertices are drawn as small circles and the edges are drawn as thin strips. Consider a cycle c of G. Is it possible to draw c as a non-intersecting closed curve inside \({\it \Gamma}\) , following the circles that correspond in \({\it \Gamma}\) to the vertices of c and the strips that connect them? We show that this test can be done in polynomial time and study this problem in the framework of clustered planarity for highly non-connected clustered graphs.
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Papers by Giuseppe DI BATTISTA