Review: TCP Nice

Prefetching of data can as a background tranfer can significantly improve
the the availability, reliability, latency and consistency. But the
challange in prefetching is to prefetch the data in a way that has no
effect on foreground operations in terms of interferance and latenies.
Current operating systems and networks donot provide aqequate support for
background tranfer. In this paper the author has purposed a variation of
TCP Vegas, called TCP Nice, protocol to support the background transfer of
data with the goal to mimimize the interferance with foregound traffic and
maximize the utilization of available bandwidth.

TCP Vegas provides a simple abstraction of zero-cost background transfers
through a self-tuning background trasport layer. This overcomes the
drawback of hand tuning the background flows that complicates the
application and cannot cater for the fluctuation in network traffic. TCP
Nice has added three components to TCP Vegas

- More sensitive congestion detection mechanism
- Multiplicative reduction in window size in responce to increasing RTT
that makes it more sensitive to congestion
- Ability to reduce congestion window below one

In order to demonstrate the effective of TCP Nice in hadling background
trasfers authors carried out a formal analysis to bound the reducation in
throughtput that foreground flows can experience. The results were then
comapred with simulation experiments carried out to stress test the system
under varying network configuration and conditions. The results show that
TCO Nice casue almost no interferance besides utilizing a significant
fraction os available bandiwidth for background flows. TCP Nice was also
tested in real world scenario over variety of internet links.

The author in this paper has tested the purposed solution using all the
dimensions e.g formal analysis, simulations and real world deployment
which is a very strong point to believe that TCP Nice is a elegant
solution to support background transfers. One main concern is that TCP
Nice is using the multiplicative reduction in windown size which in not a
very good solution in case of congested link as highlighted in some of
previous reseach becasue this mechanism is not very fair. Overall TCP Nice
is a great contribution that could be used to support massive replication
of data services.
Received on Thu Oct 05 2006 - 10:34:16 EDT