Dr. Costin Raiciu

Professor of Networking and Systems

Catedra de Calculatoare
Facultatea de Automatica si Calculatoare
Universitatea Politehnica Bucuresti, Romania

Address
Splaiul Independentei 313a
Bucuresti
Romania
Office: Room 203,
Precis Building
eml

News

12/8/2025: NEW A great overview of the innovations in the brand new Ultra Ethernet Transport which solves the problem of connecting GPUs across the multipath scale-out datacenter network.

1/9/2024

Hotnets 2024 paper

7/4/2022

Test of Time Award

PDF

4/3/2022: Our FlexOS paper has been awarded the distinguished artefact award at ASPLOS (three awards given). You can find the camera ready version here .

Code

Unikraft an OS toolkit that allows building fast, lightweight OS images around your favourite POSIX applications with great ease.
htsim simulator (for TCP, MPTCP and NDP), including datacenter topology implementations.
NDP implementation (including stack, switch and simulator).
Beamer stateless datacenter load balancer.
Symnet - a symbolic execution engine for network-wide dataplane verification.

Research Interests

Network verification: the CORNET project (ERC Starting Grant) aims to ensure networks are provably correct. It extends our Symnet/SEFL work (Sigcomm 2016) to verify P4 programs (Vera, Sigcomm 2018) and to test for equivalence between different dataplanes (netdiff, NSDI 2019).
Lightweight virtualization: LightVM is a redesign of Xen to enable booting VMs in a few ms (SOSP 2017). To achieve such low boottimes, LightVM needs small VMs, e.g. unikernels. Unikraft is an open-source project we are involved in that aims to automatically create unikernels from POSIX-compliant apps.
Datacenter networking: the NDP network stack (Sigcomm 2017) that uses a novel switch service model (trim packets to headers and forward headers/packets with weighted round robin) to construct a radical transport protocol that provides low latency and high throughput simultaneously.
Multipath TCP (MPTCP-WG, overview)
- Load balancing for Multipath TCP (HotMiddelbox 2016)
- Protocol (NSDI 2012), Congestion Control (NSDI 2011)
- Using MPTCP: in datacenters (Sigcomm 2011), mobility (MobiArch 2011 and CellNet 2012 papers), Wifi mobility (NSDI 2015), mobile energy saving (Conext 2014)

Thesis

I received my PhD from the Department of Computer Science, University College London in 2011. My thesis was ROAR: Increasing the Flexibility and Performance of Distributed Search [PDF]

Book chapters

Costin Raiciu, Janardhan Iyengar and Olivier Bonaventure - Recent Advances in Reliable Transport Protocols in Recent Advances in Networking (SIGCOMM eBook)

Publications

(Also see Google Scholar page)

2025	Ultra Ethernet's Design Principles and Architectural Innovations - Torsten Hoefler, Karen Schramm, Eric Spada, Keith Underwood, Cedell Alexander, Bob Alverson, Paul Bottorff, Adrian Caulfield, Mark Handley, Cathy Huang, Costin Raiciu, Abdul Kabbani, Eugene Opsasnick, Rong Pan, Adee Ran, Rip Sohan - arXiv preprint arXiv:2508.08906 [PDF] Generating P4 Data Planes Using LLMs - Mihai-Valentin Dumitru, Vlad-Andrei Bădoiu, Alexandru M Gherghescu, Costin Raiciu - in Computer Networks Volume 272, November 2025 [PDF] LLMic: Building a Romanian Foundation Language Model - - Vlad-Andrei Bădoiu, Alexandru M Gherghescu, Alexandru Agache, Mihai-Valentin Dumitru, Costin Raiciu - in SYNASC 2025 [PDF]
2024	Loupe: Driving the Development of OS Compatibility Layers - Hugo Lefeuvre, Gaulthier Gain, Vlad Andrei Badoiu, Daniel Dinca, Vlad-Radu Schiller, Costin Raiciu, Felipe Huici, Pierre Olivier- in ASPLOS 2024 [PDF] I've Got 99 Problems But FLOPS Ain't One - Alexandru M Gherghescu, Vlad-Andrei Bădoiu, Alexandru Agache, Mihai-Valentin Dumitru, Iuliu Vasilescu, Radu Mantu, Costin Raiciu - in Hotnets 2024 [PDF] Towards automatic exploitation of programmable networks - Mihai Dumitru, Dragos Dumitrescu, Costin Raiciu - in Netsoft 2024 [PDF]
2023	Nephele: Extending Virtualization Environments for Cloning Unikernel-based VMs - Costin Lupu, Andrei Albisoru, Radu Nichita, Doru Blanzeanu, Mihai Pogonaru, Razvan Deaconescu, Costin Raiciu - in Eurosys 2023 [PDF]
2022	An edge-queued datagram service for all datacenter traffic - Vlad Olteanu, Haggai Erran, Dragos Dumitrescu, Adrian Popa, Cristi Baciu, Mark Silberstein,Georgios Nikolaidis, Mark Handley, Costin Raiciu - in NSDI 2022 [PDF; Slides] FlexOS: Towards Flexible OS Isolation - Hugo Lefeuvre, Vlad Badoiu, Alexander Jung, Stefan Lucian Teodorescu, Sebastian Rauch, Felipe Huici, Costin Raiciu, Pierre Olivier - in ASPLOS 2022 [PDF] [Best Artefact Award]
2021	Unikraft: Fast, Specialized Unikernels the Easy Way - Simon Kuenzer, Vlad Badoiu, Hugo Lefeuvre, Sharan Santhanam, Alex Jung, Gaulthier Gain, Cyril Soldani, Costin Lupu, Stefan Teodorescu, Costi Raducanu, Cristian Banu, Laurent Mathy, Razvan Deaconescu, Costin Raiciu, Felipe Huici - in Eurosys 2021 [PDF; Video] [Awarded Best Paper] FlexOS: Making OS Isolation Flexible - Hugo Lefeuvre, Vlad Badoiu, Stefan Teodorescu, Pierre Olivier, Tiberiu Mosnoi, Razvan Deaconescu, Felipe Huici, Costin Raiciu - in HotOS 2021 [PDF; Video] Unikraft and the Coming of Age of Unikernels - Hugo Lefeuvre, Gaulthier Gain, Daniel Dinca, Alexander Jung, Simon Kuenzer, Vlad Bădoiu, Răzvan Deaconescu , Laurent Mathy, Costin Raiciu, Pierre Olivier, Felipe Huici - Usenix ;login:, July 2021 - [article] FlexOS : Vers une Isolation Flexible du Noyau - Hugo Lefeuvre, Vlad-Andrei Badoiu, Stefan Lucian Teodorescu, Pierre Olivier, Tiberiu Mosnoi, Razvan Deaconescu, Felipe Huici and Costin Raiciu - in Compass 2021 [PDF]
2020	bf4: towards bug-free P4 programs - Dragos Dumitrescu, Radu Stoenescu, Lorina Negreanu, Costin Raiciu - in Sigcomm 2020 [PDF; Video] Can we exploit buggy P4 programs? - Mihai Dumitru, Dragos Dumitrescu, Costin Raiciu - in SOSR 2020 [PDF; Video] Online Learning Multipath Transport - Tomer Gilad, Neta Rozen Schiff, Brighten Godfrey, Costin Raiciu, Michael Schapira - in Conext 2020 [PDF] Compiling Packet Programs to Reconfigurable Switches:Theory and Algorithms - Balazs Vass, Erika Berczi-Kovacs, Costin Raiciu, Gabor Retvari - in EuroP4 2020 [PDF]
2019	Dataplane equivalence and its applications - Dragos Dumitrescu, Radu Stoenescu, Matei Popovici, Lorina Negreanu and Costin Raiciu - in NSDI 2019 [PDF; Video] NDP: Rethinking Datacenter Networks and Stacks. Two Years After - Costin Raiciu, Gianni Antichi - editorial note in ACM Sigcomm Computer Communication Review Volume 49 Issue 5, October 2019 [PDF] Do You Know Why Your Web Pages Load faster? - Costin Raiciu - technical perspective in the Communications of the ACM, Volum 62, No. 7, July 2019 [PDF]
2018	Secure Opportunistic Multipath Key Exchange - Sergiu Costea, Marios Choudary, Doru Gucea, Bjoern Tackmann, Costin Raiciu - in CCS 2018 [PDF] Debugging P4 Programs with Vera - Radu Stoenescu, Dragos Dumitrescu, Matei Popovici, Lorina Negreanu and Costin Raiciu - in SIGCOMM 2018 [PDF, Technical Report, Video] Stateless Datacenter Load-balancing with Beamer - Vladimir Olteanu, Alexandru Agache, Andrei Voinescu, and Costin Raiciu - in NSDI 2018 [PDF] [Community Award Winner]
2017	Re-architecting datacenter networks and stacks for low latency and high performance - Mark Handley, Costin Raiciu, Alexandru Agache, Andrei Voinescu, Gianni Antichi, Andrew Moore, Marcin Wojcik -in SIGCOMM 2017 [PDF] [ Awarded Best Paper] My VM is Lighter (and Safer) than your Container - Filipe Manco, Costin Lupu, Florian Schmidt, Jose Mendez, Simon Kuenzer, Sumit Sati, Kenichi Yasukata, Costin Raiciu, Felipe Huici - in SOSP 2017 [PDF] [Featured on HackerNews link and YCombinator link] CloudTalk: Enabling Distributed Application Optimizations in Public Clouds - Alexandru Agache, Mihai Ionescu, Costin Raiciu - in Eurosys 2017 [PDF] Integrating Verification and Repair into the Control Plane - Aaron Gember Jacobson, Costin Raiciu, Laurent Vanbever - in HotNets 2017 [PDF; Video] Sharing CPUs via endpoint congestion control - Laura Vasilescu, Vladimir Olteanu, Costin Raiciu - in KBNets 2017 [PDF]
2016	Symnet: scalable symbolic execution for modern networks - Radu Stoenescu, Matei Popovici, Lorina Negreanu and Costin Raiciu - in SIGCOMM 2016 [PDF] Exploiting Multipath Congestion Control for Fun and Profit - Matei Popovici and Costin Raiciu - in Hotnets 2016 [PDF] Datacenter scale load balancing for multipath transport - Vladimir Olteanu and Costin Raiciu - in HotMiddlebox 2016 [PDF] OpenStack networking for humans: symbolic execution to the rescue - Radu Stoenescu, Dragos Dumitrescu and Costin Raiciu - Invited Paper in LANMAN 2016 [PDF]
2015	In-Net : In-Network Processing for the Masses - Radu Stoenescu, Matei Popovici, Vladimir Olteanu, Joao Martins, Roberto Bifulco, Felipe Huici, Mohamed Ahmed, Georgios Smaragdakis, Mark Handley and Costin Raiciu - in proceedings of ACM EUROSYS 2015, Bordeaux, France. [PDF] Towards Wifi Mobility without Fast Handover - Andrei Croitoru, Dragos Niculescu and Costin Raiciu - in proceedings of Usenix NSDI 2015, Oakland, USA. [PDF] Increasing Datacenter Network Utilization with GRIN - Alexandru Agache, Razvan Deaconescu and Costin Raiciu - in proceedings of Usenix NSDI 2015, Oakland, USA. [PDF] Oh Flow, Are Thou Happy? TCP sendbuffer advertising for make benefit of clouds and tenants - Alexandru Agache, Costin Raiciu - in HotCloud 2015, Santa Clara, USA [PDF] Lost in Network Address Translation: Lessons from Scaling the World's Simplest Middlebox - Vladimir Olteanu, Felipe Huici, Costin Raiciu - in HotMiddlebox 2015, London, UK [PDF] Good cop, Bad Cop: Forcing Middleboxes to Cooperate - Costin Raiciu, Vladimir Olteanu and Radu Stoenescu - position paper in the IAB Workshop on Stack Evolution in a Middlebox Internet (SEMI) 2015, Zurich, Switzerland. [PDF] In-Network Processing, User-Level Stacks and the Future of Internet Evolution - Felipe Huici, Costin Raiciu and Michio Honda - position paper in the IAB Workshop on Stack Evolution in a Middlebox Internet (SEMI) 2015, Zurich, Switzerland. [PDF]
2014	Using Cooperation for Low Power Low Latency Cellular Connectivity - Catalin Nicutar, Dragos Niculescu and Costin Raiciu - in proceedings of ACM Conext 2014, Sydney, Australia. [PDF] ClickOS and the Art of Network Function Virtualization - J. Martins, Mohamed Ahmed, Costin Raiciu, Vladimir Olteanu, Michio Honda, Roberto Bifulco and Felipe Huici - in proceedings of Usenix NSDI 2014, Seattle, USA. [PDF] Rekindling Network Protocol Innovation with User-Level Stacks - M. Honda, F. Huici, C. Raiciu, J. Araujo, L. Rizzo - in Computer Communication Review, April 2014. [PDF]
2013	Enabling Fast, Dynamic Network Processing with ClickOS - J. Martins, M. Ahmed, C. Raiciu, F. Huici - in procedings of HotSDN 2013 [PDF] Evolving the Internet with Connection Acrobatics - C. Nicutar, C. Paasch, M. Bagnulo, C. Raiciu - in proceedings of HotMiddlebox 2013 [PDF] SymNet: Static Checking for Stateful Networks - R. Stoenescu, M. Popovici, L. Negreanu, C. Raiciu - in proceedings of HotMiddlebox 2013 [PDF]
2012	How Hard Can It Be? Designing and implementing a deployable Multipath TCP - C. Raiciu, C. Paasch, S. Barre, A. Ford, F. Duchene, O. Bonaventure and M. Handley in procedings of Usenix NSDI, San Jose, California [PDF] [ Awarded the Community Award at NSDI 2012 ] Utilizing the Empty Half of Full Bisection Networks with GRIN - A. Agache, C. Raiciu - in procedings of HotCloud 2012 [PDF] Opening Up Black Box Networks with CloudTalk - C. Raiciu, M. Ionescu, D. Niculescu - in procedings of HotCloud 2012 [PDF] Exploring Mobile/WiFi Handover with Multipath TCP - C. Paasch, G. Detal, F. Duchene, C. Raiciu, O. Bonaventure - in procedings of CellNet 2012 [PDF] An Overview of Multipath TCP - O. Bonaventure, M. Handley and C. Raiciu - in the Usenix ;login: magazine, October 2012, Volume 37, Number 5. Download here (Usenix subscription required).
2011	Is It Possible to Extend TCP? - M. Honda, Y. Nishida, C. Raiciu, A. Greenhalgh, M. Handley, H. Tokuda - in proceedings of ACM Internet Measurement Conference (IMC) 2011, Berlin, Germany [PDF] [ Awarded the Applied Networking Research Prize by the Internet Research Task Force ] [ Featured on Slashdot ] Improving datacenter performance and robustness with Multipath TCP - C. Raiciu, S. Barre, C. Pluntke, A. Greenhalgh, D. Wischik, M. Handley - in proceedings of ACM SIGCOMM 2011, Toronto, CA [PDF] Design, Implementation and Evaluation of Congestion Control for Multipath TCP - D. Wischik, C. Raiciu, A. Greenhalgh, M. Handley in proceedings of Usenix NSDI, 2011, Boston, USA [PDF] [ Best Paper Award at NSDI 2011 ] Opportunistic Mobility with Multipath TCP - C. Raiciu, D. Niculescu, M.Bagnulo, M. Handley in proceedings of the MobiArch Workshop (colocated with ACM Mobisys), 2011, Washington DC, USA [PDF]
2010	Data Center Networking with Multipath TCP - C. Raiciu, C. Pluntke, S. Barre, A. Greenhalgh, D. Wischik, M. Handley. in Proceedings of ACM Hotnets 2010, Monterey, California [ PDF] [BibTex]
2009	ROAR: Increasing the Flexibility and Performance of Distributed Search - C. Raiciu, F. Huici, M. Handley, D.S. Rosenblum , in proceedings of ACM SIGCOMM, August 2009, Barcelona, Spain [PDF] Control of multipath TCP and optimization of multipath routing in the Internet - D.Wischik, M. Handley, C. Raiciu, invited paper in NetCoop 2009, November 2009, Eindhoven, The Netherlands.
2008	Preventing memory error exploits with WIT - P. Akritidis, C. Cadar, C. Raiciu, M. Costa, M. Castro , in proceedings of IEEE Security and Privacy (Oakland), May 2008, Oakland, USA [PDF]
2006	Reducing Congestion Effects in Wireless Networks by Multipath Routing - L. Popa, C. Raiciu, I. Stoica, D. S. Rosenblum, in proceedings of IEEE ICNP , November 2006,Santa Barbara, USA [PDF] Enabling Confidentiality in Content-Based Publish/Subscribe Infrastructures - C. Raiciu, D. S. Rosenblum, in proceedings of IEEE Securecomm , August 2006, Baltimore, USA. [PDF] Exploit Hijacking: Side Effects Of Smart Defenses - C. Raiciu, M. Handley, D.S. Rosenblum, in proceedings of ACM SIGCOMM Workshop on Large Scale Attacks and Defenses, September 2006, Pisa, Italy [PDF] Revisiting Content-Based Publish/Subscribe - C. Raiciu, D.S. Rosenblum, M. Handley, in Proceedings of the IEEE ICDCS Workshop on Distributed Event Based Systems, July 2006, Lisbon, Portugal. [PDF]
2004	Using Code Collection to Support Large Applications on Mobile Devices - L. Popa, C. Raiciu, R. Teodorescu, I. Athanasiu, R. Pandey, in proceedings of ACM MobiCom, September 2004, Philadelphia, USA [PDF]

Internet Standards

RFC 6182 Architectural Guidelines for Multipath TCP Development - A Ford, C. Raiciu, M. Handley, S. Barre, J. Iyengar - March 2011
RFC 6356 Coupled Congestion Control for Multipath Transport Protocols - C. Raiciu, M. Handley, D. Wischik - October 2011
RFC 6824 TCP Extensions for Multipath Operation with Multiple Addresses - A. Ford, C. Raiciu, M. Handley, O. Bonaventure - January 2013
RFC 7430 Analysis of Residual Threats and Possible Fixes for Multipath TCP (MPTCP) - M. Bagnulo, C. Paasch, F. Gont, O. Bonaventure, C. Raiciu - July 2015

Students

Postdoc: Sergiu Costea (now at ETH Zurich), Andrei Voinescu (now at Fitbit).
PhD: Alexandru Agache (graduated, now at Amazon Bucharest), Vladimir Olteanu, Laura Vasilescu (now at Google Zurich), Costin Lupu, Dragos Dumitrescu
Master's: Radu Stoenescu, Andrei Croitoru (graduated, now at Google), Catalin Nicutar (graduated, now at Facebook)

Talks

Google Tech Talk: overview of Multipath TCP and its Applications
NSDI 2012 Talk: How Hard Can It Be? Designing and Implementing a Deployable Multipath TCP

Teaching

Fall 2016 - Advanced Topics in Distributed Systems (Masters Course) (link, UPB CS Students only).
Spring 2017 - Operating Systems (3rd year undergraduate)

Professional Activities

Chair for the Jochen Liedtke committee 2024.
Committee for selecting the ACM Dissertation Award 2021.
Technical Program Committee: OSDI 2024, Sigcomm 2024, NSDI 2023, NSDI 2022, NSDI 2021, Sigcomm 2020,OSDI 2020, SIGCOMM 2018, NSDI 2018, SOCC 2018, Eurosys 2018, Conext 2015, 2016 and 2017, ANCS 2016, PAM 2016, INFOCOM 2014 and 2015,IMC 2014 and 2012,
HotMiddlebox 2015 Co-Chair
ACM CONEXT 2013 Workshops Co-Chair
Co-chair of the ACM CONEXT 2011 Student Workshop
Judge for the South-Eastern Europe Regional ACM Programming Contest - 2011, 2012

Grants (Principal Investigator)

CORNET (Provably Correct Networks) - ERC Starting Grant funded by the EC (5 years, starting 1/2018)
SafeNet - ERC Proof of Concept grant (18 months, starting 9/2019).
150K USD gift funding from VMWare (2021)
100K USD gift funding from Huawei for research in systems and networking. (9/2018)
UNICORE - H2020 project, funded by EC (3 years, starting 1/2018), in the area of lightweight virtualization.
SUPERFLUIDITY H2020 project, funded by the EC (2.5 years, starting 7/2015)
SSICLOPS H2020 project, funded by the EC (3 years, starting 2/2015)
Trilogy 2 FP7 project, funded by the EC (3 years, starting 1/2013)
MobiL4 project funded by the Romanian Government (joint project with Intel Romania) (2.5 years starting july 2012)
Funding from CISCO's University Research Program to work on Evolving Networks with Multipath TCP (1 year starting in august 2011)
CHANGE FP7 project (3 years, starting in 10/2010)
Amazon AWS Research Grant (1 year, starting 1/2011)

Media

CORNET, my ERC project, is one of the "media-friendly" ERC Starting Grant projects funded in 2017: see ERC project highlights.

Fun

The slides for my outrageous opinions talk on our ride to Sigcomm are here.
Wifi TPC - outrageous opinions talk given at Sigcomm 2015 that used Wifi quality to estimate how good the presented paper really is. Using Wifi quality information gathered during the conference, we were able to predict the best paper award before it was announced officially.