A Comparison of Active Queue Management Algorithms Using the OPNET Modeler

1. A Comparison ofActive Queue Management AlgorithmsUsing the OPNET Modeler Chengyu Zhu and W.W.Yang,university of Ottawa James Aweya,Michel Ouellete,and Delfin Y.Montuno,Nortel Networks Lijian(李健) Electronics and Information Eng Huazhong University of Science and Technology Nov. 2012

2. THE WORKING PRINCIPLE OF AQM Advantage: Reduce the packet loss rate Reduce the queuing delay Queue Recipient Router The link The link Recipient

3. AN OVERVIEW OF AQM (2) BLUE 1. BLUE uses the instantaneous queue length and link utilization as indicators of traffic load and congestion 2. By adjusting pwith respect to the instantaneous queue length and link utilization (idle periods), BLUE aims to maintain the queue length at a predefined threshold (3) STABILIZED RED 1. The SRED algorithm is designed to stabilize the queue size at a level independent of the number of active connections. 2. The zombie list is equivalent to a list of Mrecently seen flows augmented with a countand timestampfield. 3. SRED computes the drop probability as a function of the queue size q with respect to the buffer capacity B (4) DYNAMIC RED 1. The DRED algorithm uses a simplefeedback control approach to randomly discard packets in the queue. 2. The drop probability pd(n) of DRED is adjusted according to the max-min operation of the filtered error signal, the control gain a, and the buffer size B. (1)RANDOM EARLY DETECTION

7. return

8. return

9. CONCLUSION (1)From the simulation results, we observe that the RED algorithm does not perform as well as the other algorithms in a congested network. (2) BLUE was also not effective at stabilizing the queue size. (3)DRED and SRED both stabilize queue size very well, thus resulting in a more predictable packet delay in the network.

10. Thank you!