Director, Research Laboratory / Research Group Leader

Kenjiro CHO

Contact Info: IIJ Research Lab. Iidabashi Grand Bloom, 2-10-2 Fujimi, Chiyoda-ku Tokyo 102-0071, Japan
phone:+81-3-5205-6464 email:kjc at iijlab dot net

My research focus is on understanding network dynamics from a global view, which contributes to turning the Internet into a simpler, more flexible and more dependable communication infrastructure.

Research Topics

The Internet that is an inter-network of distributed autonomous networks shows surprisingly complex behaviors due to interference of various technologies. For example, a local optimization sometimes has a negative impact to the global system, and such a global impact is often overlooked. We also need to take it into consideration that, even if there is no problem at the moment, it might affect future technical evolution. It is important for the global Internet that we look at technologies with a global perspective, and understand their technical impacts as well as social impacts.

My research projects include measurement of traffic dynamics, and quality of service.

  • Traffic measurement from Japanese ISP backbones
  • MAWI: Publicly available packet traces from the WIDE backbone
  • NECOMA Project (cybersecurity for improved resilience against cyber threats)
  • agurim: a traffic monitoring tool by multi-dimensional aggregation
  • Network anomaly detection
  • Network security analysis
  • DNS measurement
  • IPv4/IPv6 comparative path analysis
  • Network data visualization
  • ALTQ (a framework for packet scheduling)


Selected Recent Papers
  • Kenjiro Cho, Jean-Fran├žois Baffier.
    An Autonomous Resource Management Model towards Cloud Morphing.
    Edgesys2023. Rome, Italy. May 2023.
  • Romain Fontugne, Anant Shah, Kenjiro Cho.
    Persistent Last-mile Congestion: Not so Uncommon.
    ACM IMC 2020. October 2020. (url).
  • Shinyoung Cho, Romain Fontugne, Kenjiro Cho, Alberto Dainotti, Phillipa Gill.
    BGP hijacking classification.
    TMA 2019. Paris, France. June 2019. (pdf).
  • Hamed Haddadi, Vassilis Christophides, Renata Cruz Teixeira, Kenjiro Cho, Shigeya Suzuki, Adrian Perrig. SIOTOME: An Edge-ISP Collaborative Architecture for IoT Security. IEEE IoTSec 2018, April 2018. (pdf).
  • Kenjiro Cho. Recursive Lattice Search: Hierarchical Heavy Hitters Revisited. ACM IMC 2017, London, UK, November 2017. (pdf).
  • Romain Fontugne, Patrice Abry, Kensuke Fukuda, Darryl Veitch, Kenjiro Cho, Pierre Borgnat, Herwig Wendt. Scaling in Internet Traffic: a 14 year and 3 day longitudinal study, with multiscale analyses and random projections. IEEE/ACM Transactions on Networking, vol.25(4). pp2152--2165. August 2017. (pdf).

Tools and Datasets

Open Source Software

Open Datasets

Professional Activities

  • ACM Recognition of Service Award (for contributions to ACM IMC2015). December 2015.
  • ACM Recognition of Service Award (for contributions to ACM SIGCOMM2007). November 2007.




  • OpenPGP publickey fingerprint: 4DDF 260C CB14 6D28 CD83 2BE4 555B E672 640B DA0C
  • (old publickey fingerprint: FFC4 5675 A05F 8AE9 3CDC A95C 91CF CAD0 D9FB 511F)