![]() Modified by incorporating into these a control function to condition routers for better In this thesis three existing Active Queue Management (AQM) mechanisms are Without any consideration to the applications specific requirements. Unfortunately, the current Internet offers only a best-effort service to all applications Traditional applications, have more strict delay constraints and less strict loss constraints. For example, interactive multimedia applications, unlike ![]() These newĪpplications have different requirements in terms of throughput and delay than However in the recent years the Internet is increasingly supporting emergingĪpplications such as IP telephony, video conferencing and online games. Traditionally the Internet is used for the following applications: FTP, e-mail and Web School of Computing, Informatics and Media The development and performance evaluation of some new active queue management methods for internet congestion control based on fuzzy logic and random early detection using discrete-time queueing analysis and simulation. Performance Modelling and Evaluation of Active Queue Management Techniques in Communication Networks. The University of Bradford theses are licenced under a Creative Commons Licence. This suggests that when traffic is largely of a non bursty nature, instantaneous queue length might be a better congestion measure to use rather than the average queue length as in the more traditional models. After extensive experimentation, the results show that the proposed REDD, REDD1, REDD2 and REDD3 algorithms and some of the proposed analytical models such as DRED-Alpha, RED and GRED models offer somewhat better results of mean queue length and average queueing delay than these achieved by RED and its variants when the values of packet arrival probability are greater than the value of packet departure probability, i.e. The performance measures are calculated based on data collected only after the system has reached a steady state. The simulations for RED, GRED, ARED, DRED, BLUE, REDD, REDD1, REDD2 and REDD3 are run ten times, each time with a change of seed and the results of each run are used to obtain mean values, variance, standard deviation and 95% confidence intervals. The proposed analytical models are experimentally compared with their corresponding AQM simulations with reference to the above performance measures to identify which approach gives the most satisfactory results. The proposed analytical models use the instantaneous queue length as a congestion measure to capture short term changes in the input and prevent packet loss due to overflow. Furthermore, a set of discrete-time queue analytical models are developed based on the following approaches: RED, GRED, DRED and BLUE, to detect the congestion at router buffers in an early stage. These methods are named REDD1, REDD2, and REDD3 and their performances are also compared with RED using the above performance measures to identify which method achieves the most satisfactory results. Moreover, three methods based on RED and fuzzy logic are proposed to control the congested router buffers incipiently. A comparison is made between the proposed REDD, RED and ARED approaches regarding the above performance measures. This approach is called Dynamic RED (REDD), which stabilises the average queue length between minimum and maximum threshold positions at a certain level called the target level to prevent building up the queues in the router buffers. This thesis presents a new AQM approach based on the RED algorithm that determinesĪnd controls the congested router buffers in an early stage. A comparison is conducted between five known AQM methods, Random Early Detection (RED), Gentle Random Early Detection (GRED), Adaptive Random Early Detection (ARED), Dynamic Random Early Drop (DRED) and BLUE, based on several performance measures, including mean queue length, throughput, average queueing delay, overflow packet loss probability, packet dropping probability and the total of overflow loss and dropping probabilities for packets, with the aim of identifying which AQM method gives the most satisfactory results of the performance measures. Specifically, these AQM methods are surveyed in detail and their strengths and limitations are highlighted. ![]() To enhance the performance when the network becomes congested, several different active queue management (AQM) methods have been proposed and some of these are discussed in this thesis. This may result in a poor network performance with reference to average packet queueing delay, packet loss rate and throughput. Congestion occurs in network routers when the number of incoming packets exceeds the available network resources, such as buffer space and bandwidth allocation. Since the field of computer networks has rapidly grown in the last two decades, congestion control of traffic loads within networks has become a high priority.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |