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Kenjiro CHO Research Director

Kenjiro CHO Photo

Research Director
Kenjiro CHO

The Internet is global, folks!

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 ISP backbones
  • DNS measurement
  • IPv4/IPv6 comparative path analysis
  • Publicly available packet traces from the WIDE backbone
  • Network data visualization
  • ALTQ (a framework for packet scheduling)


including ALTQ, aguri, and ttt.

Professional Activity




English Papers
  • Kenjiro Cho, Kensuke Fukuda, Hiroshi Esaki and Akira Kato,The Impact and Implications of the Growth in Residential User-to-User Traffic, SIGCOMM2006, pp207-218, Pisa, Italy, September 2006
  • Tomoo Mizukami and Kenjiro Cho,Tunneling with Service Discovery: A romote access model and Implementation, IEEE CCNC2006, Las Vegas, NV, January 2006
  • Toshiyuki Miyachi, Kenjiro Cho and Yoichi Shinoda,On the Stability of Server Selection Algorithms against Network Fluctuations, AINTEC2005, Bangkok, Thailand, December 2005
  • Kazuhide Koide, Shunsuke Fujieda, Kenjiro Cho and Norio Shiratori, TCP Retransmission Monitoring and Configuration Tuning on AI3 Satellite Link, AINTEC2005, Bangkok, Thailand, December 2005
  • Matthew Luckie, Kenjiro Cho and Bill Owens, Inferring and Debugging Path MTU Discovery Failures, Internet Measurement Conference 2005, Berkeley, CA, October 2005
  • Kensuke Fukuda, Kenjiro Cho and Hiroshi Esaki, The impact of residential broadband traffic on Japanese ISP backbones, ACM SIGCOMM CCR SPECIAL ISSUE: Measuring the internet's vital statistics, vol35(1), pp15-22, January 2005
  • Kenjiro Cho, Matthew Luckie and Bradley Huffaker, Identifying IPv6 Network Problems in the Dual-Stack World, SIGCOMM'04 Network Troubleshooting Workshop, Portland, Oregon, September 2004
  • Kenjiro Cho, Fitting theory into reality in the ALTQ case, ASIA BSD conference, Taipei, Taiwan, March 2004
  • Yuji Sekiya, Kenjiro Cho, Akira Kato, Ryuji Sonegawa, Tatsuya Jinmei and Jun Murai, Root and ccTLD DNS server observation from worldwide locations, PAM2003, La Jolla, CA, April 2003
  • Ryuji Somegawa, Kenjiro Cho, Yuji Sekiya and Suguru Yamaguchi, The Effects of Server Placement and Server Selection for Internet Services, IEICE Trans, on Commun, Vol.E86-B No.2, February 2003, p.542-551
  • Kenjiro Cho, Ryo Kaizaki and Akira Kato, Aguri: An Aggregation-based Traffic Profiler, In Proceedings of QofIS2001 (published by Springer-Verlag in the LCNS series), September 2001
  • Kenjiro Cho, The Design and Implementation of the ALTQ Traffic Management System, dissertation, Keio University, January 2001
  • Kenjiro Cho, Koushirou Mitsuya and Akira Kato, Traffic Data Repository at the WIDE Project, In Proceedings of USENIX 2000 Annual Technical Conference: FREENIX Track, San Diego, CA, June 2000
  • Kenjiro Cho, Flow-valve: Embedding a Safety-valve in RED, In Proceedings of IEEE GLOBECOM99 Global Internet Symposium, Rio de Janeiro, December 1999,
  • Kenjiro Cho, Managing Traffic with ALTQ, In Proceedings of USENIX 1999 Annual Technical Conference: FREENIX Track, Monterey CA, June 1999
  • Kenjiro Cho, A Framework for Alternate Queueing: Towards Traffic Management by PC-UNIX Based Routers, In Proceedings of USENIX 1998 Annual Technical Conference, New Orleans LA, June 1998
  • Kenjiro Cho and Kenneth P.Birman, A Group Communication Approach for Mobile Computing, In Proceedings of IEEE Workshop on Mobile Computing Systems and Applications, Santa Cruz, December 1994, pp95-102


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