The Research On Implementation Of QoS Agnet Based DiffServ Network

As the Internet is growing up increasingly, the QoS requirements by kinds of network traffic become more and more higher, while the available network resources are still limited. How to resolve the contradiction between the demands and the supplies has become a research highlight inQoS area. So a new network architecture------the 'Differentiated Servicesnetwork1 is introduced to ensure the QoS as transferring dataflow on the IP backbone networks.Based on the work-out of various researches currently existed, this thesis proposes a QoS Agent System, that is based on the DiffServ network, to control the traffic admissions and manage the network resources in the DS domain. The thesis also describes the architecture, the elements and the adaptive conditioning mechanism of the QoS Agent System. On the aspect of the intra-DS domain and inter-DS domain, the network resources allocation and the control of dataflows for the QoS Agent System are also discussed.This thesis has implemented partial functions of the QoS Agent System on the NS2 platform and done simulations of the data transmission in the DS-Agent domain. The results of the simulations have shown that (1) when the whole bandwidth resources can satisfy the requests of all the dataflow, the difference of transferring performance between popular DS domain and DS-Agent domain can be ignored; (2) when the whole bandwidth resources can not satisfy the requests of all the dataflow, the performance of the DS-Agent domain is much better than the popular DS domain because of its low packet lost rate and the fairness of bandwidth allocation.In the end, after evaluating the QoS Agent System and its simulation scheme, the thesis also points out some unsolved problems of QoS Agent System, such as the bottleneck and reliability of this system etc., and gives some suggestions for improving it.