Comparison of tail drop and active queue management performance for bulk-data and Web-like Internet traffic

This paper compares the performance of tail drop and three different flavors of the RED (random early detection) queue management mechanism: RED with a standard parameter setting, RED with an optimized parameter setting based on a model of RED with TCP flows, and finally a version of RED with a smoother drop function called "gentle RED ". The performance is evaluated under various load situations for FTP-like and Web-like flows, respectively. We use measurements and simulations to evaluate the performance of the queue management mechanisms and assess their impact on a set of operator oriented performance metrics. We find that in total (i) no performance improvements of RED compared to tail drop can be observed; (ii) fine tuning of RED parameters is not sufficient to cope with undesired RED behavior due to the variability in traffic load; and (iii) gentle RED is capable of resolving some of the headaches on RED but not all.