Paper Info
Title
The effects of active queue management and explicit congestion notification on web performance
Abstract
We present an empirical study of the effects of active queue man- agement (AQM) and explicit congestion notification (ECN) on the distribution of response times experienced by a population of users browsing the Web. Three prominent AQM schemes are consid- ered: the Proportional Integral (PI) controller, the Random Expo- nential Marking (REM) controller, and Adaptive Random Early Detection (ARED). The effects of these AQM schemes were stud- ied with and without ECN. Our primary measure of performance is the end-to-end response time for HTTP request-response ex- changes. For this measure, our major results are:  If ECN is not supported, ARED operating in byte-mode was the best performing AQM scheme, providing better response time performance than drop-tail FIFO queuing at offered loads above 90% of link capacity. However, ARED operating in packet- mode (with or without ECN) was the worst performing scheme, performing worse than drop-tail FIFO queuing.  ECN support is beneficial to PI and REM. With ECN, PI and REM were the best performing overall schemes, providing sig- nificant response time improvement over ARED operating in byte-mode. In the case of REM, the benefit of ECN was dra- matic. Without ECN, response time performance with REM was worse than drop-tail FIFO queuing at all loads considered.  ECN was not beneficial to ARED. Under current ECN imple- mentation guidelines, ECN had no effect on ARED perform- ance. However, ARED performance with ECN improved sig- nificantly after reversing a guideline that was intended to police unresponsive flows. Nonetheless, overall, the best ARED per- formance was achieved without ECN.  Whether or not the improvement in response times with AQM is significant (when compared to drop-tail FIFO), depends heavily on the range of round-trip times (RTTs) experienced by flows. As the variation in flows' RTT increases, the impact of AQM and ECN on response-time performance is reduced. We conclude that AQM can improve application and network per- formance for Web or Web-like workloads. In particular, it appears likely that with AQM and ECN, provider links may be operated at near saturation levels without significant degradation in user- perceived performance.
Year
DOI
Venue
2007
10.1109/TNET.2007.910583
IEEE/ACM Transactions on Networking
Keywords
Field
DocType
Delay,Pi control,Proportional control,Guidelines,Computer science,TCPIP,Programmable control,Adaptive control,Time measurement,Degradation
Random early detection,Web performance,Control theory,Computer science,Simulation,Active queue management,Computer network,Response time,Queueing theory,Network performance,Explicit Congestion Notification
Journal
Volume
Issue
ISSN
15
6
1063-6692
Citations 
PageRank 
References 
16
0.76
15
Authors
4
Name
Order
Citations
PageRank
Long Le11015.89
Jay Aikat216815.53
Kevin Jeffay31909228.25
F. Donelson Smith41176287.74