The Research On Congestion Control Algorithm Of ABR Service In ATM Network And Application In Switch

Because the traditional circuit switching has low utilization, and the traditional packet switching can't guarantee the quality of service and has low switching speed ,a new technology -ATM emerges as times require. To guarantee the Qos ATM divided the service into five categories: Constant Bit Rate (CBR), Real-Time Variable Bit Rate (rt-VBR),Non-Real-Time Variable Bit Rate(nrt-VBR), Available Bit Rate(ABR), Unspecified Bit Rate(UBR) and adopt flow control mechanism respectively. The mechanism of ABR service is unique closed-loop control with feedback, which make the flow control of ABR service is very important to guarantee the Qos of ATM networks.In this paper, the key technology of binary flow control algorithm of ABR service and congestion detection has been studied based on analyzing the current binary flow control algorithm of ABR service. On the basis of the theoretical analysis, we emphasize on the implementation issues and the compatibility to current standard. Main achievement of this paper are summarized as follows:Based on modeling of binary algorithm of ABR flow control, to the solve the defect of EFCI algorithm such as, response to congestion slowly, the oscillation amplitude of ACR and queue length too large, we presented the An ABR flow control scheme with information of queue length, The result of simulation indicates that the new algorithm has better real-time control ability than basic EFCI algorithm. It has lower oscillation amplitude of ACR and queue length , higher link, buffer utilization rate , faster relieve congestion and better cost/performance. This demonstrates that choosing parameter real-timely according to network switch point's buffer amplitude.In chapter 4th, on the basis of discussing the detection congestion according to the speed, in order to optimize the performance of the binary algorithm further, we presented the An ABR flow control scheme with virtual information of queue length based on speed. The result of simulation indicates that the new algorithm has solved the defect of basic EFCI algorithm than E-EFCI algorithm.In chapter 5th, we has discussed the software and hardware framework of the switch briefly and introduce technology standard, design thinking on design switch. Finally, conclusion is drawn on the defect and the improvement of research further more in this paper.