Tcp Over The Obs Study

OBS, which has been studied adequately for years, is considered to have the most promising fundamental architecture for the next generation Internet. The network architecture of OBS has been theoretically modeled and has been implemented in labs. As the most important protocol working in Transport Layer, the performance of TCP in the OBS network has arouse the extensively attention from industry. Relevant research of"TCP over OBS"has been launched form that time on. Based on previous work, this paper further discusses the performance of"TCP over OBS"in the following four areas.(1) The process of TCP-flow segmentation by the OBS network: Through simulations and theory analysis, we find that the number of TCP packets contained in a burst usually takes on decreasing trend when a TCP flow get across the OBS network. We call this phenomenon as"The process of flow segmentation". As a result, the"Correlation Gain"of TCP traffic is reduced, which in turn makes the throughput drops down. We proposed a strategy to tackle this issue by increasing the ACK assembly time, which significantly improve the performance of TCP over OBS in terms of throughput.(2) The disorder of TCP traffic in OBS network: The disorder of TCP traffic cause"False Fast Retransmit"in TCP sender, which in turn makes the throughput drops down. The probability of disorder of TCP traffic just right exists in OBS network. Through the theory analysis, this paper point out the material condition that the probability come into existence. We proposed a corresponding strategy to tackle this issue. Through simulations, we prove the availability of this strategy.(3) The problem of synchronized packets loss in OBS network: The problem of synchronization packet loss has been proposed in current industry. This paper proposes a new solution based on priority to solve this problem. The solution avoids the defect in original method, which increased the burst loss rate in OBS core node. The results of simulation prove its availability.(4) The performance evaluation of Vegas protocol over OBS network: the performance of Vegas protocol over OBS network has been evaluated and three new technologies of this protocol have been experimented in the OBS network. The conclusion is that: the mechanism of congestion avoid of vegas protocol can not availably detect the congestion condition of OBS network.