Network Link Delay Estimation And Its Application In The Anycast Routing

The knowledge of network parameters allows network engineers to improve the network design, control and operate. For instance, the Internet users may estimate the link level characteristics such as loss and delay from end-to-end measurements, which are important parameter of Internet's performance. Due to the size and the decentralized nature of the Internet, monitoring its behaviors and diagnose its performance degradation is challenging. Network tomography has been regarded as one of the most promising methodologies for performance evaluation and diagnosis of the massive and decentralized Internet.The estimation of the link level delay is one of the most important study part in Network tomography. In this paper, we study a novel estimation approach for the network tomography problem. Unlike previous methords, this approach does not work with the model distribution directly, but rather it works with the its characteristic function that is the Fourier transform of the distribution. And this algorithm is computationally more efficient and yields more accurate results than previous methods under some some perfect and hypothetical conditions. Unfortunately, the real situation is complicated and there is some difference between the actual end-to-end measurement data and the ideal ones. Furthermore, it makes the evaluated results fluctuating badly. In this paper, we introduce a new constraint Network Tomography to solve this problem, which adds some constraint information collecting with the help of some partial internal nodes to the Fourier Domain model. In fact, the constraint network tomography can improve the precision of evaluated parameters better than the other method. Comparing with the results, it proves that applying constraint optimization method to Network Tomography of Fourier Domain is very effective. The new method has a number of advantages over the existing ones including more stability and flexibility, more accurate estimation and identifiability. Finally, the simulation result demonstrate the performance of the propose approach when there are some obvious errors in the measured-data.The networks always are not trees but reticulations in real situation. In this paper, we divide the reticulate networks into single trees whose link level delay could be estimated through the methord named constraint link delay estimaton in Fourier Domain. Then we apply the estimation results in anycast routing which used the multi-objective optimization algotithms. Especially, both the constraint link delay in Fourier Domain inference and application are investigated. In chapter 3 , we introduce how to build the mathematical model for these problems and the steps to the estimated final results Besides this, in chapter 4, how to validate the routing algorithms using NS2 tools is also discussed.Regarding the problems the single-objective optimization anycast routing algorithm has, we introduce a novel multi-objective optimization anycast routing algorithm which based on the link level delay estimation. We will propose some new methods and ideas which combine the constraint estimation technology of link delay and the anycast routing algorithm. The results of the estimation are used in constructing the main optimization function of the anycast routing model. Finally, we validate its performance using extensive NS2 simulations in MPLS network model and its affectivity is proved by experiments.