Review: Controlling High-Bandwidth Flows at the Congested Router

Review: Controlling High-Bandwidth Flows at the Congested Router

Reviewer: Di Niu

This is an exciting paper which offers strong supports for the
arguments it presents. It proposes RED-PD, a mechanism that uses drop
history to identify high-bandwidth flows, and control their
throughput in times of congestion. By doing this, the mechanism not
only alleviates congestion greatly, but also protects unmonitored
flows from the excessive bandwidth occupation by high-bandwidth flows
and ensures max-min fairness. RED-PD enjoys a privilege of simplicity
by only keeping state for high-bandwidth flows.

The paper first offer trace-measurement which shows in Internet only
a small fraction of lows occupy a large fraction of traffic both in
large-scale and small-scale measurement periods. It is therefore
possible to control the small fraction of high-bandwidth flows to
achieve congestion control, while only keeping moderate state
information.

RED-PD identifies high-bandwidth flow by drop history. When a flow
exceeds a target bandwidth T, it will be restricted to T if there is
enough demand from other flows. As T is pushed down, non-mornitered
flows will receive more bandwidth. And this target bandwidth T is
calculated from packet dropping rate and RRT. Then it uses
preferential dropping to reduce the traffic of high-bandwidth flows.
RED-PD is made to avoid link under-utilization. It does not only
protect unmonitored flows from high-bandwidth ones, but also enforces
fairness among unmonitored flows using the iterative increase and
decrease of a flow's dropping probability. Extensive NS based
experimental results were presented to evaluate the scheme.
Received on Mon Oct 02 2006 - 19:14:50 EDT