This pages is under major renovation - please come back soon.
Presentation Slides for Recent Papers
Research Interests and Areas
My primary research interest is in optical networks, at the networking layer.
The development of dWDM (allowing many channels of communication over the same
fiber) and wavelength routing (allowing fast switching at the optical layer),
coupled with the huge increment in available bandwidth that the use of fiber
allows, has changed the way we look at some networking problems, as well as
given rise to new ones. My interest is currently in two major areas, that
of traffic grooming and fault tolerance. I have a secondary interest in
performance and management of optical networks, as well as ad-hoc networking.
The quantum jump in transmission speed due to the use of fiber has not been
accompanied by a similar improvement in processing speed at intermediate
network processing elements (routers, switches). As a consequence, either
the fiber has to be severely underutilized (not a preferable solution, and
not viable in the long run), or many processing elements have to be deployed
to conventionally route/switch at each intermediate (network interior) node.
This latter solution can be prohibitively expensive. In addition, the
processing equipment is all electronic, thus delay is incurred in electro-optic
conversion every time the packets/cells contained in an optical signal must
be routed. This will usually be necessary because the bandwidth of even a
single wavelength is likely to be much larger than the typcial user channel
bandwidth, thus many slower speed traffic streams will be multiplexed (probably
TDM) over each wavelength channel.
It becomes very attractive to allow some (hopefully the bulk) of
the traffic to be switched optically, using wavelength routing, and resort to
electro-optic conversion and electronic processing only when it cannot be
avoided. This problem has been called traffic grooming in literature.
In the general case, as well as in many quite restrictive cases of topology
and traffic patterns, this problem is computationally intractable. My research
concentrates on finding theoretical results characterizing optimal solutions
to different traffic grooming problems and relations between them, as well as
the development of heuristic solutions. See the technical report linked below
for a thorough overview and review.
Protection and Restoration
As tomorrow's networks grow in speed and reliability, they are going to take
over many functions for which computer networking is not currently the primary
or preferred vehicle. This is going to result in tomorrow's optical backbone
acquiring a "lifeline" characteristic which it does not have now. Reliability
and fault tolerance are going to be important issues in such a network. The
protection and restoration research area addresses these issues. Usually, we
make a distinction between proactive (plan beforehand for a link or node
failure) or reactive (once a failure occurs, respond, taking network state
into account) approaches. Approaches can focus purely on the optical layer or
involve co-operation between the optical layer and its client layer (such as
IP). Research areas address design optimization for static as well as dynamic
(blocking characteristics) considerations.
The following technical reports are available from the Computer Science
Technical Report Archive.
See the resume section for refereed publications.
- Traffic Grooming in Star NetworksM by
Chen, Dutta and Rouskas,
NCSU CSC Technical Report TR-2004-16
- Traffic Grooming in Path, Star, and Tree Networks:
Complexity, Bounds, and Algorithms by Dutta, Huang and
Rouskas, NCSU CSC Technical Report TR-2002-15
- A Survey of Optical Network Survivability
by Washington, Perros, and Dutta,
NCSU CSC Technical Report TR-2002-08
- A Networking Perspective for Intelligent Utilization of Directional
Antennas in Ad Hoc Wireless Networks: The TANDEM Approach by Dutta and
Sichitiu, NCSU CSC Technical Report TR-2002-03
- Traffic Grooming in WDM Networks: Past and Future by Dutta and
Rouskas, NCSU CSC Technical Report TR-2002-02
- A Sequence of Bounds for the Problem of Minimizing Electronic Routing
in Wavelength Routed Optical Rings by Dutta and Rouskas,
NCSU CSC Technical Report TR-2000-11
- A Survey of Virtual Topology Design Algorithms for Wavelength
Routed Optical Networks by Dutta and Rouskas,
NCSU CSC Technical Report TR-99-06
Prospective Research Students
If you are considering research work with me, thank you for your interest in my
research. These are some of the points to consider with respect to possible
research work with me:
- My primary research area is in optical networks. I would want to work
with students to advance my research in this field. I regret that at this time
I cannot guide your research if you would like to work in a different area.
- I would want to focus my energies in guiding research that is beneficial both
for the student and the for the research community. In other words, to work
with me you should be working towards a thesis that is part of your degree; if
you simply have an interest in the research area and would like to read about it,
you may want to browse my publications. Similarly, research to be truly useful
must be written up and published; I assume implicitly that if you work with me
you intend to produce publishable material.
- I currently have no funded grants, so I cannot support you financially at
this time. You would need to have your own support in the form of a
TA contract or other source. If you start working with me, I may be able to
obtain support for you later, but this is not guaranteed by any means. I may
not receive such support, or if I do I may have to choose between different
students in apportioning the funds.
- Since I can only work with a limited number of students,
I would have a strong bias towards working with Ph.D. students
rather than MS students; MS students in their first semester would be an
outside possibility (especially if a thesis is part of their degree
requirements). I have no unit of work for a single semester or
so, and the background work itself may take significant time, more than the
average MS student would want to consider.
Also, I would tend to consider students who I have known
through the courses I teach before others.
- To work in my research area, the following background is desirable. You
should obviously have the basic Computer Science background including OS,
architecture, algorithms. Naturally, you must also have more thorough coverage
of the networking area, familiarity with basic networking concepts as well as
specific protocols such as TCP/IP, ATM etc. In addition, the following are
areas/tools/techniques that we are likely to use:
- Optimization - linear and non-linear, LPs, ILPs
- Complexity Theory - NP-completeness, equivalence
- Graph Theory - graph colorability, graph algorithms
- Queuing Theory - queueing networks, blocking characteristics
- If you would like to talk to me about the possibility of doing research
work with me, please e-mail me to make an appointment. When we meet, I request
that you bring with you:
- An academic transcript, showing all coursework (with grades) performed
during Baccalaureate or post-Baccalaureate studies, including the current
- A resume, with all job experience (academic or industrial). Please include
your current department, degree programme, expected date of graduation, etc.
- A personal statement, telling me how your current degree work fits in your
long term plans, etc.
Students sometimes ask me about independent studies: while basically it is a
good idea, I cannot undertake to guide you in one at this time. I also encourage
you to do most of the work for an independent study before the semester you
actually register for it; this proves intent and reduces the chance that you
may not get a satisfactory grade for it.
I wish you luck in your research endeavours, whether with myself or other faculty