Research On Efficient Estimation Of Bandwidth Along Network Path

Charactering the network status as precise as possible becomes increasing important with the explosive growth of the available resource and users in Internet. As one of the crucial metrics to picture the network characteristics, bandwidth has wide-spread applications in numerous areas such as overlay network, desigh and management in wireless network, traffic engineering, network security and so on. In addition, the end-to-end bandwidth of network path is consistent with the experience of common users. Therefore, bandwidth estimation, especially the end-to- end bandwidth estimation, becomes a hot issue in recent years.In this thesis, we focus mainly on the estimation of end-to-end bandwidth or path bandwidth (including both capacity and available bandwidth) without cooperation of the network internal devices such as switches or routers etc.After review briefly the state-of-the-art in bandwidth estimation, we first analyze the major factors affecting the bandwidth estimation. We discuss these factors from network as well as from end-host carrying the measurement process. We found that the diverse network characters such as the different route policy and multi-channel of network path will influence the estimation drastically. In addition, the capability of end-host, i.e. the clock resolution or granularity, may limit the effectiveness of measurement tools.In general, the main estimating processes can be divided into three steps: data collecting, data filtering and continuous processing. We further discuss the possible factors depressing or improving the execution of each sub-step. In most cases, actually, estimation accuracy, deploy- ment flexibility and overhead (including the cost in deployment, probing and computing) are in contradictive, that is, we will have higher cost and less flexible deployment if we wish to obtain higher accuracy.The major focus of the thesis is the estimation of both the capacity and available bandwidth alone a given network path. We present two schemes, e.g. COPP and CapEst, aiming for estimating effectively the capacity and available bandwidth of path respectively. Both schemes are independent of the asychronization of the two-side clocks of measured path.The name COPP comes from the particular probe scheme, Chirps of Packet Pairs. A chirp of packet pairs is composed of several packet pairs with decremental inter-packet spacing. After discussing the rigorous definition of available bandwidth, the novel two-steps estimating methodology, e.g. partial and final step, is presented. In partial step, COPP sends several chirps of packet pairs. After each chirp is received, we find out all turning points in the chirp, and then give these points distinct weight according to the degree of experienced distortion. Turning point is such a packet pair that is disturbed more obviously by cross traffic in contrast to its neighbor pairs. In each partial step, a partial estimate can be obtained and equal to the weighted average of...