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Roch
Guerin Dept. Elec. & Sys. phone: 215 898-9351 |
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Current ·
Recent ·
Past |
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Journals |
Where Do I Come From?
(Short one-page bio
in pdf format)
I grew up in
a suburb of Paris, France, called Saint
Cloud and
went to high school in
I did my undergraduate studies at ENST, Paris, and actually spent my last year in Toulouse in the South-West of France in the Satellite Communications Systems department (don't ask me why, but it was fun). I did my undergraduate thesis on "Jamming Resistant Multiple Access Methods for Satellite Systems."
After finishing my undergraduate studies, I attended Caltech, where I received both my MS (1984) and Ph.D. (1986) from the Electrical Engineering department. My Ph.D. was supervised by Prof. Edward Posner and was entitled "Queueing and Traffic in Cellular Radio" (sorry, no link. That was way too long ago...).
After graduating from Caltech, I joined the IBM T.J. Watson Research Center, where I worked on many aspects related to quality of service in broadband networks for over 12 years. When I left I was the manager of the Network Control and Services department (sample of projects I was involved in while at the IBM T.J. Watson Research Center).
I joined the department of Electrical and Systems Engineering at the University of Pennsylvania in October 1998 as the Alfred Fitler Moore Professor of Telecommunications Networks.
In 2001, I
co-founded Ipsum Networks (now part of Iptivia)
with Raju Rajan, a former colleague from my days at the
I was elected IEEE Fellow in January 2001 and served as a Member-at-Large on the Board of Governors of the IEEE Communications Society until the end of 2002. I was an editor for the IEEE/ACM Transactions on Networking and the IEEE Transactions on Communications, served as the chair of the Technical Committee on Computer Communications of the IEEE Communications Society from 1997 to 1999, and was the General Chair of the IEEE INFOCOM'98 conference.
I became an ACM Fellow in 2006, served as the Editor of the ACM SIGCOMM Computer Communication Review (CCR) until the end of 2001 and returned as an area editor for CCR from 2005 to 2006. I was Program co-Chair of the ACM SIGCOMM'2001 conference and General Chair of the ACM SIGCOMM 2005 Conference, and Program co-Chair, together with Olivier Bonaventure, of the 2007 ACM CoNEXT conference. I have also been on SIGCOMM's Technical Advisory Committee from 2001 till 2005.
I served on the Scientific Advisory Board (Scientific Council) of France Telecom for two consecutive terms from 2001 till 2006, and on Samsung's Technical Advisory Board in 2003 and 2004.
Courses
I Have Recently Taught or Currently Teach
Email
me in case you want access to some of the course material I used, as our course
portal is currently not allowing external access…
· Networking Theory and Fundamentals (TCOM 501 - Spring'05): An entry level graduate course on the basic analytical techniques used in the design and modelling of networking systems.
· Advanced Networking Protocols (TCOM 502 – Fall'04, Spring'05-08): An entry level graduate course on a range of protocols and technologies used in networking. The courses covers everything from addressing, to packet forwarding and lookup techniques, to routing protocols for which it provides an in-depth treatment of RIP, EIGRP, OSPF, IS-IS and BGP, as well as a general discussion of multicast protocols ending with a review of PIM-SM and SSM. Topics such as MP-BGP and MPLS/BGP VPNs are also discussed. The course ends with a brief introduction to various efforts for introducing service differentiation in modern networks, and reviews both the underlying mechanisms for enforcing differentiation and the signalling protocols (RSVP and RSVP-TE) used to configure them.
· Introduction to Networks and Protocols (TCOM 400/500 - Fall'05-07): An introductory combined upper level undergraduate and entry level graduate course on networks and protocols. The course introduces the basic mechanisms and technologies involved in enabling modern end-to-end communications with an emphasis on packet networks. The course follows a bottom-up approach roughly along the various layers of the OSI model but focusing primarily on layers present in IP networks, and using examples derived from current network technologies and applications. The course by nature emphasizes breadth over depth in any specific topic, but provides a solid foundation on which students interested in pursuing further studies in networking can build.
General Research Interests
·
My
general area of research is networking, although I have also been looking at a
number of application level issues that arise when applications need to
communicate over a packet network. In the networking area, I still have a couple
of projects related to Quality-of-Service (QoS), with a focus on scalable and
flexible mechanisms that require minimum configuration and interactions between
the network and users. However, in general and in spite, or rather because of
many years investigating QoS topics, I have reached the conclusion that the
large majority of QoS solutions turn out to be more expensive than the
resources they are trying to manage. Hence, the bulk of my current activities
are directed at what I would characterize as “Robust Networking.” What I
mean by that are a set of techniques that allow you to design networks and
network mechanisms that can ensure efficient operation across a broad range of
operational characteristics. For example, in the traffic engineering area, this
means identifying routing schemes that are tolerant of link and node failures
as well as changes in traffic patterns, in the sense that they result in “good”
overall network performance even in the presence of such perturbations. In the
more traditional QoS area, this means devising mechanisms that support service
differentiation across a broad range of traffic characteristics, i.e., are not
heavily dependent on the proper configuration of policers. I am also interested
in extending the concept of robust networking to the wireless setting, where
the combination of greater limitations on resources and the more dynamic nature
of users and of the network infrastructure itself, creates a new set of
problems. One area of recent interest is that of leveraging diversity as a
means for improving robustness in large-scale networks (see the presentation “Size
Does Matter! From the Age of Closed-Loop to the Age of Open-Loop” given at NeXtworking’07 – 2nd
COST-NSF Workshop on Future Internet, April 2007, Berlin, Germany, together
with the accompanying one-page
abstract for additional details).
Current
and Recent Activities in the Multimedia and Networking Lab
The
Multimedia and
Networking Lab has
a number of ongoing projects that typically involve a mixture of analysis and
experiments. The experiments are often carried out using a testbed consisting
of multiple routers, hubs, and switches from different vendors. In particular,
part of the testbed has been built using equipment generously donated by 3COM, IBM, and Lucent. Most of the projects carried out in the lab
are supported through NSF grants, as well as
through additional support from industrial partners such as Sprint Labs, Nortel Networks, and Siemens.
Current Projects
On the Economic
Viability of Network Architectures. This is a joint
project with Prof. Kartik
Hosanagar from the Wharton Business School and Profs. Andrew Odlyzko and Zhi-Li Zhang from the University of
Minnesota, which is funded by NSF under the FIND initiative (NSF grant
CNS-0721610). The project has three main
thrust areas aimed at assessing the economic viability of new network
architectures:
1.
Investigate
and quantify the potential benefits of key proposed architectural features such
as virtualization, integration, and diversity;
2.
Explore
when and why the existence of a formidable incumbent (today’s Internet) can
affect the emergence of new technologies;
3.
Develop
models that account for how the openness and flexibility of a network
architecture can foster the adoption of new technology, and its ultimate
success.
Related
Publications
·
Forthcoming.
A Framework for
Manageability in Future Routing Systems.
This
is a joint project with the
Related
Publications
·
K.-W.
Kwong, R. Guerin, A. Shaikh, and S. Tao, “Improving Service
Differentiation in IP Networks through Dual Topology Routing.” Proc. ACM CoNEXT'07, New York, NY, December
2007.
Distributed Uplink Scheduling in CDMA
Networks. This is a project in collaboration with Ashwin Sridharan and partially
funded by Sprint Labs, which explores
issues that arise in CDMA networks when devices (mobiles) are afforded some
level of independence in making transmission decisions, instead of being under
the tight control of a base station.
Giving mobile devices some flexibility in deciding when to transmit and
at what rate is increasingly desirable because of the diversity of applications
they are now capable of running and that exhibit a broad range of communication
requirements. However, allowing devices
to make individually controlled transmission decisions may affect global
system performance, and one of the goals of this project is to explore this
trade-off in a number of different settings.
Related
Publications
·
A.
Sridharan, R. Subbaraman, and R. Guerin, “Distributed Uplink Scheduling
in CDMA Networks.'' Proc.
Networking'2007,
Towards
Large-Scale Flat Networks. This is a
project sponsored by and in collaboration with Siemens. Flat networks like Ethernet have many
advantages in terms of simplicity and flexibility, e.g., plug-&-play and
little or no configuration requirements.
However, they suffer from a number of potential scalability
limitations, which have limited the scope of their deployments and promoted the
use of (hierarchical) routed solutions to build large networks, the Internet
being a case in point. This work is not
aimed at replacing the Internet with one big flat network, but it explores
various issues aimed at improving the scalability of flat networks. In particular, it targets two important
factors that affect scalability: (i) reliance on broadcast for address
discovery; and (ii) loop prevention during path changes.
Related
Publications
·
S.
Ray, R. Guerin, and R. Sofia, “A Distributed Hash Table
based Address Resolution Scheme for Large-scale Ethernet Networks.” Proc. ICC’07,
·
S.
Ray, R. Guerin, and R. Sofia, “Distributed Path Computation
without Transient Loops: An Intermediate Variables Approach.” Proc. ITC’20,
Recent Projects
Data
plane aggregation.
This
work was supported through NSF grant ITR-0085930 and
aimed at developing a better understanding of the relations that exist between
QoS provided as some aggregate level, e.g., a service class as in the
Differentiated Services model, and the actual QoS that individual users
experience. Of particular interest are models that allow explicit evaluation of
individual QoS measures, and their use in identifying characteristics of user
traffic that can result in significant differences between individual and
aggregate QoS measures. This led to the
development of models that allow the evaluation of the loss probability
experienced by individual connections and when and why it differs from the
aggregate loss probability. The environment that is assumed consists of a
single FIFO queue where all the individual users belonging to the same service
class are multiplexed. A separate but related perspective is that
of security, namely, understanding the extent to which a single (or a few) user
can affect the performance of many other users. In that context, we
investigated the extent to which more sophisticated attack schemes can defeat
existing mechanisms, and used that understanding towards developing better
defenses.
Related Publications
·
Y.
Xu and R. Guerin, "Individual QoS
versus aggregate QoS: A loss performance study." IEEE/ACM Trans. Netw.
Vol. 13, No. 2, April 2005. For a short version, see also
the proceedings of INFOCOM'2002,
·
Y.
Xu and R. Guerin, "On Evaluating Loss Performance Deviation: A
Simple Tool and Its Practical Implications." In Proceedings of 2nd international workshop on QoS in
Multiservice IP Networks (QoS-IP 2003),
· Y. Xu and R. Guerin, “On the Robustness of Router-Based Denial-of-Service (DOS) Systems.” ACM Computer Communication Review, Vol. 35, No. 3, July 2005.
·
Y.
Xu and R. Guerin, “A
Double Horizon Defense Design for Robust Regulation of Malicious Traffic.”
In Proceedings SecureComm 2006,
Traffic
engineering in IP networks. This is work was aimed at better
understanding what is achievable using different traffic engineering
techniques, and more important how one can devise solutions that are not highly
sensitive to the quality of the “input” on which traffic engineering decisions
are based. One problem that was investigated included how to best group traffic
flows to minimize the number of distinct paths that had to be established in
order to achieve optimal performance, and how this grouping affected both long
term and short term performance. Another problem focused on devising minor
modification to existing IP forwarding in order to allow the implementation of
near optimal traffic distribution over existing IP networks. Yet another area
of investigation involved evaluating traffic engineering solutions that can
provide resilience to changes caused by link or node failures or by
fluctuations in traffic patterns. This work was supported in part by NSF grants ANI-9902943
and ITR-0085930, and by a gift from Sprint ATL, and was partly carried out in collaboration
with Christophe Diot
(now at Thomson Paris Research Lab) and his
former group at Sprint ATL. Another aspect of this work, supported by
supported by NSF grant ITR-0085930,
investigated the use of overlay networks to deliver better service “guarantees”
over IP networks by leveraging the (path) diversity offered by the availability
of a large number of peers. Part of this
investigation was carried in the context of real-time applications such as VoIP
and video (see above), but another area of focus was to develop simple
techniques for quickly identifying peers that could act as “good” relay nodes
for alternate overlay paths, i.e., overlay paths with performance that was largely
uncorrelated with that of the default path.
The challenge was to retain the benefits of having access to a very
large number of possible choices, while devising simple and scalable solutions,
i.e., that required little processing and only minimal storage.
Related Publications
· A. Sridharan, S. Bhattacharyya, C. Diot, R. Guerin, J. Jetcheva, and N. Taft, "On The Impact of Aggregation on The Performance of Traffic Aware Routing." Technical Report, University of Pennsylvania, June 2000 (short version presented at ITC'17, Salvador da Bahia, Brazil, September 24-28, 2001).