Research On End To End QoS Metric In IP Network

In the traditional IP networks ,the service"Best effort" is used to delivery all packets the same way at each node and the policy "FIFO" is applied to transmit to destination. It is not guaranteed any reliability and performance (eg.delay) when packet transmissing. Real-time transactions will be affected when FTP transaction occurring frequently and HTTP transaction which includes image files are in networks;On the other hand, much bandwidth was consumed by multimedia transaction, the key transaction can not get reliable transmission by present network. In order to solve this problem, the notion QoS was introduced to Internet which has become an important research field in computer network in fact.In the QoS research field, QoS controlling, management, billing and measurement are related to each other and can not be divided. Thereinto, QoS metric is very important to many Internet application and protocols (especially the application refered to bulk data transmission and multimedia flow limited by delay). At the present, the technology of QoS metric is still not mature, the study of QoS metric is in progress at the start, and the result of QoS metric research is less and the standard has not been made, it is a new hot point in IP QoS technology study.Sum up, it is very important to have a systematic reaseach on QoS metric technology and measurement infrastructure, performance evaluating methodology. This thesis mainly solves the end-to-end QoS metric problem under IP network. Nowadays many measurement systems are for network which doesn't not support QoS, and it gets the performance parameters such as topology, traffic, availability through accessing MIB by SNMP protocols, this system is not for QoS-enabled network and demands on very high rights on the managed network, meanwhile, additional overload is created and much bandwidth is comsumed when bulk measured performance data are transformed to the central network management system. In many positions, such traditional passive metric methodology can not been applied because of such reasons. In order to make up the disadvantages,this thesis demonstrates from IP QoS technology, QoS performanceparameter system, QoS parameter mapping to network parameter metric to the key technology in network metric, and active metric methodology is put forward and appliedto end-to-end QoS metric, at the last, QoSMeter system was developed and implemented under IntServ model.QoSMeter system only needs the edge hosts and no especial rights awarded by ISP or NSP who controlled routers and switches. The QoSMeter gets performance parameter by active measurement and decreases the overload at the best. This thesis discusses the infrastructure, system flow and implementation of QoSMeter in detail, meanwhile, the logic figure and results of experiment are provided too.The measured result of QoSMeter not only provides the basis to QoS billing and QoS management, but also gives effective reference to QoS-enabled network performance. QoSMeter system has a clear structure, flexibility, small overhead, good extensibility and portability, it has important meaning to QoS metric research.