The Research And Application For QoS In IP Network

Quality of Service is a Composite Indicator,which is used to measure the satisfaction of a service.Along with the rapid development of network technology and the wider application of Internet,the network service also presents the characteristics of diversification,from traditional data transferring business to multi-media business such as video,audio and so on.Different network services result in different network resource requests.However,the original intension of IP is just to supply a kind of "Best Effort" service without guarantee of the reliability and time delay of the IP passage.It is suitable for those data operation that demands accuracy,but not time delay;while for those real-time operations,such as voice and video,the quality of the service can not be guaranteed.How to deal with QoS (Quality of Service) from peer to peer? With present IP Routing Technology and Network structure,it is not easy to expand the whole network and to provide various services.Not undertaking QoS requirement has become the obstacle of the IP Network's development.How to resolve the problem and provide the satisfied service according to the special proceeding flexibly needs instant answers.First,the paper introduces the definition of QoS,expatiates the research status of IP QoS at home and abroad,and then introduces the researching meaning of IP QoS and the deficiency in IP network.So brings forward the problems that need to solve. On that basis,the paper introduces all kinds of mechanisms for QoS realizing at present,including IntServ model,DiffServ model,MPLS and kinds of related techniques and their basic principles and working,and points out theirs advantages, disadvantages and the application environments,but all those mechanisms can't realize the complete QoS guarantee by themselves,so even appears the techniques of IntServ model combined with DiffServ model,MPLS combined with IntServ model, and MPLS combined with DiffServ model,which want to learn from others strong points and close the gap and help each other to realize the QoS mechanisms from peer to peer.However,those precepts only solve part of the problems.There is a new model based on MPLS,which is with a view to the whole network,and provides full QoS guarantee from peer to peer.The new model is a model which is combined with the models of IntServ,DiffServ and MPLS.Subsequently the paper introduces the Token Bucket algorithm's application in IP QoS,its basic principle and the flow,brings forward the deficiency of the algorithm and gives the detailed description of the modified algorithm.At last,the paper sums up the achievements and deficiencies, brings forward the existent problem in IP QoS,and gives the research direction for the future.