Virtual Network Laboratory Support Environmental Research

The successful setup of Virtual Laboratory will be dependent on reliable real-time data stream transmission in the network environment. Although the congestion control research of host-ends has made great strides,the current queue management mechanism in router is not able to provide end-to-end congestion control mechanism to sustain the above environment, namely, the unfairness of assigned bandwidth or drop-rate for different types of flows and the synchronization of all TCP flows in network. So it is necessary to improve the classical queue management mecnanism such as Drop_Tail and RED in order to boost the QoS(Quality of Service ). This article analyzes the main traits of host-ends congestion control and all kinds of fashionable queue management machanism ,which include Queue Mechanism with absolute priority ,Weighted Fair Queue Mechanism and Class-based Queue Mechanism . Further , we emphatically analyze the method of combined RED and ECN which is recommended by IETF . In the analysis we find that with the increase of Internet traffic ,RED mechanism doesn't effectively prevent the packets from dropping . In comparison with Drop_Tail Algorithm , RED Algorithm surely eliminates the bias against the bursty traffic(TCP),but increases the drop probability of smooth traffic(UDP) . So on the bases of the analytic RED mechanism , we make an improvement in maintaining the fair bandwidth shares among all flows in bottleneck links,which we call New_RED Algorithm and classfies all flows according to bandwidth shared by per flow. Finally the article also compares the simulated performance between RED mechanism and New_RED mechanism by the use of NS . The simulated results verify that New_RED mechanism will work better.