Stefano Vissicchio

Lecturer @ UCL

s.vissicchio (at) cs (dot) ucl (dot) ac (dot) uk

University College London
Department of Computer Science
Gower Street
London, WC1E 6BT, UK

I have joined the Department of Computer Science at University College London in October 2016, after 4 years as post-doctoral researcher at Universite catholique de Louvain in Belgium and 3 years as PhD student at Roma Tre University in Italy. More information on my background is reported in the About me page.

My research activity focuses on theory, algorithms and systems for efficiently and reliably managing communication networks. I always look for practical problems that are intellectually challenging to solve. And I strive to tackle such problems adopting a rigorous approach, based on leveraging the insights gained by theoretical analyses and formal tools to design new techniques, algorithms, and fully-fledged system prototypes.

I am always looking for highly motivated, talented PhD students. To enter the PhD programme at UCL, candidates must pass the standard UCL admission process. If you are interested in working with me, please drop me an email!

Teaching Research Overview Selected Publications Software


I am currently involved in teaching the following courses.

  • Networked Systems, as module leader.

  • Computer Architecture and Concurrency, as module leader.

  • Computer Systems, as teaching staff member.

  • Design and Professional Skills, as teaching staff member.

Research Overview

An overview of the main topics on which my research activity has focused.

  • Partially centralized networked systems: Theory, architecture and techniques to profitably combine centralized (SDN) and distributed (traditional) control-planes, for the greater good. Our contributions range from an overview of the research space (CCR11) and a general control-plane theory (INFOCOM15) to concrete architectures and techniques (like Fibbing, DEFO, and IBSDN).

  • Fine-grained monitoring: Architectures and systems for advanced monitoring and anomaly detection. Mainly, we proposed and assessed the feasibility of control-plane message collectors based on packet cloning (INM10), traffic-matrix estimators based on programmable routers (PRESTO10), warning systems for BGP policy violations (TNSM16), hardware-bug detectors exploiting segment routing (SCMon), and generic, fine-grained traffic monitoring systems for ISPs (Mille-feuille,Stroboscope).

  • Network updates: Complexity results, algorithms and systems to change packet-forwarding paths in a running network with guaranteed service continuity. We considered several network-update problems, in IGP-only (like SIGCOMM11 and ToN15a), BGP-running (see INFOCOM13 and ToN13), SDN (especially, FLIP) and generic multi control-plane (INFOCOM15,ToN17) networks.

  • Network testing: Methodologies, techniques and tools for checking control-plane correctness before deployment on production networks. Our contributions span configuration checkers for distributed protocols in traditional networks (TNSM11,ToN15b), and black-box testing of OpenFlow controllers (TASTE).

  • Routing theory: Graph-based modeling and formal analysis of distributed network protocols, notably policy-based routing ones as BGP. Our main results include the characterizations of the BGP expressive power and complexity of related routing problems (ICNP13), as well as the identification of sufficient and necessary conditions for guaranteed configuration correctness (ICNP09,INFOCOM12).

  • Measurements: Analyses of active measurements on Internet routing. We conducted large-scale measurement campaign to support key claims in our papers (see, for example, the ToN15b paper on iBGP Policies). We have also performed bias analyses of existing measurement infrastructures, including distributed platforms as RIPE Atlas (IMC13) and publicly-available datasets like RIS/Routeviews BGP ones (Networking14).

Selected Publications

Hereafter, a list of the most important articles that I have co-authored (with many great collaborators!). A complete list is available on my Publications page.

  • S. Gao, M. Handley, S. Vissicchio. Stats 101 in P4: Towards In-Switch Anomaly Detection. In Proc. Hotnets, 2021. (paper)

  • T. Holterbach, E. C. Molero, M. Apostolaki, A. Dainotti, S. Vissicchio, L. Vanbever. Blink: Fast connectivity recovery entirely in the data plane. In Proc. NSDI, 2019. (paper)

  • N. Gvozdiev, S. Vissicchio, B. Karp, M. Handley. On Low-Latency-Capable Topologies, and their Impact on the Design of Intra-domain Routing. In Proc. SIGCOMM, 2018. (paper) (slides) (talk)

  • O. Tilmans, T. Buhler, I. Poese, S. Vissicchio, L. Vanbever. Stroboscope: Declarative Network Monitoring on a Budget. In Proc. NSDI, 2018. (paper) (talk) (Web site)

  • T. Holterbach, S. Vissicchio, A. Dainotti, L. Vanbever. SWIFT: Predictive Fast Reroute. In Proc. SIGCOMM, 2017. (paper) (talk) (Web site)

  • S. Vissicchio, L. Cittadini. FLIP the (Flow) Table: Fast LIghtweight Policy-preserving SDN Updates. In Proc. INFOCOM, 2016. (paper) (talk) (journal version)
    Selected as INFOCOM 2016 Best Paper Award Runner-up

  • S. Vissicchio, O. Tilmans, L. Vanbever, J. Rexford. Central Control over Distributed Routing. In Proc. SIGCOMM 2015. (paper) (talk) (Web site)
    Selected as SIGCOMM 2015 Best Paper, awarded with the IRTF Applied Network Research Prize 2016

  • R. Hartert, S. Vissicchio, P. Schaus, O. Bonaventure, C. Filsfils, T. Telkamp, P. Francois. A Declarative and Expressive Approach to Control Forwarding Paths in Carrier-Grade Networks. In Proc. SIGCOMM 2015. (paper) (talk) (Web site)

  • S. Vissicchio, L. Cittadini, G. G. Xie, O. Bonaventure, L. Vanbever. On the Co-Existence of Distributed and Centralized Routing Control-Planes. In Proc. INFOCOM, 2015. (paper) (talk)

  • S. Vissicchio, L. Vanbever, O. Bonaventure. Opportunities and Research Challenges of Hybrid Software Defined Networks. ACM SIGCOMM Computer Communications Review. 44(2):70- 75. April 2014. (paper)

  • M. Chiesa, L. Cittadini, G. Di Battista, L. Vanbever, S. Vissicchio. Using Routers to Build Logic Circuits: How Powerful is BGP? In Proc. ICNP, 2013. (paper)
    Selected as ICNP 2013 Best Paper

  • S. Vissicchio, L. Vanbever, C. Pelsser, L. Cittadini, P. Francois, O. Bonaventure. Improving Network Agility with Seamless BGP Reconfigurations. IEEE/ACM Transactions on Networking. 21(3):990-1002. June 2013. (paper)
    Awarded with the IRTF Applied Network Research Prize 2013

  • C. Pelsser, L. Cittadini, S. Vissicchio, R. Bush. From Paris to Tokyo: On the Suitability of ping to Measure Latency. In Proc. IMC, 2013. (paper)

  • L. Vanbever, S. Vissicchio, C. Pelsser, P. Francois, O. Bonaventure. Seamless Network-Wide IGP Migrations. In Proc. SIGCOMM, 2011. (paper)

  • L. Cittadini, G. Di Battista, M. Rimondini, S. Vissicchio. Wheel + Ring = Reel: the Impact of Route Filtering on the Stability of Policy Routing. In Proc. ICNP, 2009. (paper)


Some pointers to the code produced by my collaborators and myself for our research projects.

  • REPETITA: a software framework for repeatable experiments on traffic engineering (TE) algorithms. It includes more than 250 real topologies, the implementation of state of the art TE algorithms (with IGP weight optimization and segment routing), and easy-to-run analyses

  • SWIFT inference algorithm and VM: predictively rerouting traffic to drastically speed up reaction to remote inter-domain failures

  • Fibbing controller: profitably using distributed routing protocols for centralized control

  • DEFO optimization module: optimizing forwarding paths with Constraint Programming

  • FLIP algorithm: computing fast, low-memory and policy-preserving updates of OpenFlow networks by combining rule replacements and tag-and-match operations

  • Hybrid SDN update algorithms: guaranteeing usage of either initial or final paths throughout the update of traditional, SDN and mixed networks