| Summary: | 碩士 === 國立彰化師範大學 === 資訊工程學系 === 106 === With the rapid development of science and technology, the network user's bandwidth demand is increasing. As a result, optical networks that can provide large network bandwidth are becoming increasingly important. Optical Burst Switching (OBS) is an optical switching technology which can be a key factor to reach all-optical networks and be more practical than Optical Circuit Switching (OCS) and Optical Packet Switching (OPS). However, in a OBS network packet losses could occur even at low traffic load situation due to its bufferless nature. This will significantly reduce the performance of TCP. Therefore, how to distinguish a packet loss is caused by network congestion or random contention is a critical and important issue for TCP over OBS networks.
In this thesis, we propose a new loss-based TCP, ATABA-TCP, which is suitable for OBS networks. We make OBS edge nodes plus a mark on packet to notify TCP sender of burst assembly state. A TCP sender may utilize this information to estimate the current network load. When a TCP sender detects packet losses, the congestion window size (CWND) can be appropriately adjusted based on the frequency of the packet loss event and the current network load level. Through the simulation results in nOBS, we can find that ATABA-TCP achieves better performance than that of SAIMD.
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