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 currently have openings for PhD students. Successful candidates must pass the standard UCL admission process. If you are interested in working with me, don't hesitate to drop me an email!

News Teaching Research Overview Selected Publications Software


Latest updates on my research activity.

  • March 2019: Thomas has presented Blink at NSDI 2019.

  • December 2018: Blink, our data-plane solution to fast reroute upon remote Internet failures, at line rate, has been accepted at NSDI 2019!

  • December 2018: Francois presented our paper on robustly disjoint paths at CoNext.

  • November 2018: Edgar presented our paper on hardware-accelerated control-planes at HotNets.

  • October 2018: our survey on network updates, with a special emphasis on SDN updates, has been accepted for publication at IEEE Communications Surveys and Tutorials (early-access version, prior ArXiv paper)

  • September 2018: our paper on implementing control plane (functions) in programmable *hardware* has been accepted at HotNets 2018

  • September 2018: our work on configuring paths that remain disjoint after failures has been accepted for publication at CoNext 2018

  • August 2018: participation in SIGCOMM 2018, where Nikola presented our work on low-delay routing in ISPs (slides, video)

  • July 2018: Computer Communications has accepted our measurement study on the correlation between routing changes and data-plane packet losses in an operational ISP network (Renater)

  • July 2018: participation in Coseners 2018, the UK Academic Meeting on Systems and Networks

  • May 2018: honored to have been a member of the PhD thesis committee of Renaud Hartert, from UCLouvain

  • May 2018: our work on the interplay between path allocation, topology design and input traffic for low-latency routing within ISPs has been accepted at SIGCOMM 2018!

  • April 2018: participation in NSDI 2018 and INFOCOM 2018. In the former, Olivier Tilmans presented our paper on Stroboscope (slides and video)

  • March 2018: TPC member for INFOCOM 2019

  • December 2017: Stroboscope, our monitoring-on-a-budget system for ISPs, has been accepted at NSDI 2018!

  • December 2017: TPC member for SIGCOMM 2018

  • November 2017: participation in IMC 2017

  • October 2017: our position paper on low latency routing on "meshy" ISPs has been accepted at Hotnets 2017

  • October 2017: REPETITA, our proposal to ease repeatable experiments on traffic engineering algorithms (with data on more than 250 topologies, implementation of segmnent routing algorithms, and easy-to-run analyses), is publicly available: Check out our arXiv paper, and our GitHub repository!


I am currently involved in teaching the following courses.

  • Computer Systems (Spring 2019), as class staff member.

  • Networked Systems (Fall 2018), co-led with Mark Handley.

  • Design and Professional Skills (Fall 2018), co-led with Mark Handley.

My past teaching activity encompasses: co-teaching Network Systems (Fall 2017) with Mark Handley; co-teaching Design and Professional Skills (Fall 2017) with George Danezis; being teaching assistant and provide individual lectures in Advanced and Basic Networking courses at UCLouvain (2012-2016) and at Roma Tre (2009-2011).

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.

  • 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 with 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

  • SCMon prototype: monitoring an entire network from a single box with Segment Routing