review: Analysis and Design of an Adaptive Virtual Queue (AVQ) Algorithm for
Active Queue Management
- What is the best Active Queue
Management method? Should
indications to the end nodes of congestion be in the form of marking the
packets or by just dropping them?
What should be considered optimal between goodput
and delay latency?
- A comparative analysis of
several distinct Queue management techniques. An introduction to an Adaptive Virtual
Queue method that uses packet marking for notifications and a virtual
queue for decisions.
- A. The different queue management methods
(Type of notification):
GKVQ (Packet marking)
PI (Packet dropping)
- AVQ uses Explicit Congestion Notification to
notify users of congestion. When it
detects the onset of congestion it marks a bit in the packet header that
the end node interprets as a dropped packet, without having to actually
drop the packet. This increases the
goodput by reducing retransmissions.
- The algorithm maintains a
virtual queue that has a smaller virtual capacity than the actual buffer. Then when this queue has overrun, it is
interpreted as congestion approaching the actual queue threshold, and
packets are marked explicitly to slow the sending from the end users. This prevents the actual queue from ever
dropping packets, but also slows users sending rates in the event of
approaching congestion. The virtual
queue is dynamic and does not have to depend on the size of the actual
- Critique the main
System researchers and
builders should recognize that often the best methods are created by
combining two marginal methods of creating the same results into one
method. Often the extra overhead of
combining them is less than the performance gain of each method.
- Significance- 2
The article is more of an implementation change
than an actual discovery. The packet marking has already been done
by GKVQ, and the active queue can for the most part be replaced by
placing a threshold on a fraction of the whole actual queue. The thought of having a preliminary
threshold and marking indication bits before actually dropping is far
- Convincing- 2 Each of the implementations
are explained and they do present some actual network data, but it is
very limited in scope and not very dynamic. The conditions seem to be optimized in
an effort to crowd out the good results of GKVQ and to display the
weaknesses of RED and PI.