Analysis and Design of an Adaptive Virtual Queue Algorithm for Active Queue Management
- State the problem the paper is trying to solve.
The main problem the paper is trying to solve is how to design and analyze a virtual
queue-based marking scheme for Active Queue Management in Internet Routers.
- State the main contribution of the paper: solving a new problem, proposing a
new algorithm, or presenting a new evaluation (analysis). If a new problem, why
was the problem important? Is the problem still important today? Will the
problem be important tomorrow? If a new algorithm or new
evaluation (analysis), what are the improvements over previous algorithms or
evaluations? How do they come up with the new algorithm or evaluation?
The main contribution of this paper is that it presents a new Active Queue
management scheme called Adaptive Virtual Queue (AVQ). It also presents an
experimental and a mathematically strong argument for why the scheme is stable in
the presence of feedback delays, is able to maintain small queue lengths, and is
robust in the presence of extremely short flow when parameters are design using their
presented rules. The problem is still relevant today as we look for ways to maintain
stability in the face of growing traffic and congestions on the Internet.
- Summarize the (at most) 3 key main ideas (each in 1 sentence.)
The three 3 key main ideas are:
(1) The authors present a new scheme for Active Queue Management called Adaptive
Virtual Queue and study its following properties: stability in the presence of
feedback delays,its ability to maintain small queue lengths and its robustness in
the presence of extremely short flows.
(2) The authors present a simple rule based on control theory-defined stability to
design the parametes fo the AVQ algorithm.
(3) The authors compare the performance of the algorithm through simulation with
several well-known AQM schemes such as RED, REM, PI controller and a non-adaptive
virtual queue algorithm.
- Critique the main contribution
- Rate the significance of the paper on a scale of 5
(breakthrough), 4 (significant contribution), 3 (modest contribution), 2
(incremental contribution), 1 (no contribution or negative contribution).
Explain your rating in a sentence or two.
I give this paper a rating of 4 because it presents significant analysis of Active
Queue Management using modern Control Theory and its ideas about stability. This is a
novel acheivement since control theory is a very appropriate analysis tool given that
congestion on the internet is concerned with stability and speed of stability.
- Rate how convincing the methodology is: how do the authors justify the solution
approach or evaluation? Do the authors use arguments, analyses, experiments,
simulations, or a combination of them? Do the claims and conclusions follow from the
arguments, analyses or experiments? Are the assumptions realistic (at the time of the
research)? Are the assumptions still valid today? Are the experiments well designed?
Are there different experiments that would be more convincing? Are there other
alternatives the authors should have considered? (And, of course, is the paper free of
The authors' methodology was rather convincing in a mathematical sense. The authors
defined their algorithm using a linearized model of their non-linear TCP/AQM model
and then did a state-space analysis of the effects of changing it various parameters.
The authors performed a number of experiments to try to prove that there algorithm
was effective at maintaining stability, small queues, and robustness in the presence
of small flows, as compared to other algorithms that have previous been presented.
- What is the most important limitation of the approach?
The most important limitation of such an approch is that it can be very convoluted to
most readers and can often be so elusive that is both difficult to understand and
also to critique and evaluate for errors. The limitation of their experimental
approach was that there can be question to how accurately their experimental models
simulate the real internet and the performance of all the algorithms on the real
- What lessons should researchers and builders take away from this work. What
(if any) questions does this work leave open?
The lessons that researchers should take away from this work are that it is possible
to do a Control Theory/State-space analysis of the Internet and its congestion
algorithms given the correct model and the correct representation of the problem.
Using Control Theory/State-Space analysis can yield useful information and insight
into the performace and limitations of proposed algorithms.