Experiments and Analysis of TCP-ACK Prioritization

[[abstract]]由於資訊科技的蓬勃發展，使得無線網路的速度越來越被現代人要求。而雲端也越來越熱門。他們有很多的TCP 流量。這些情況TCP跟Ack就很有可能會互搶頻寬。本論文就是在研究如何提高Ack的優先權(Priority)，達到提升Throughput和降低Round Trip Time(RTT)。在TCP Segment Format欄位中，Acknowledge Number(Ack)是當接收端確認收到的封包無誤後，回傳給傳送端的一個機制。如果提高了Ack的Priority使得傳送端能更快的收到Ack，傳送端就可以更短的RTT傳送更多的封包，甚至於提升Throughput。在本論文中實驗了三種不同環境下提高Ack Priority後的效果，這三種環境分別是無線網路環境、Adhoc環境以及Wired環境，三種環境都存在TCP與Ack互搶頻寬的情況。由實驗結果的比較圖得知，只要是在TCP與Ack互搶頻寬的情況下，提升Ack的Priority就可以達到提升Throughput和降低RTT。[[abstract]]Due to the rapid development of information technology, wireless transmission speed is expected more and more. Also, cloud computing becomes popular. Both come with large amount of TCP traffics. In this thesis, we focus on the flow control in TCP. Because of the basics of TCP Flow Control, TCP and Ack is likely to compete with each other for bandwidth. We study the Ack Priority policies during transmission to reduce Round Trip Time(RTT) and enhance Throughput. In the TCP Segment Format, Acknowledge Number (Ack) is to confirm the received packet and is replied to the sender. If we increase the Ack Priority, it enables the sender to receive Acks sooner. And then the sender has shorter RTTs and sends more packets thereafter. So Throughput is upgraded. Three experiments in this study demonstrate the similar results, when Ack Priority is changed. There are the Wireless infrastructure, wireless Ad hoc, and a wired point to point connection in our study, which are to experience the situations of limited bandwidth and there exist bandwidth competition among TCP segments and their Acks. The experiments all show that Ack Priority increase reduces RTT and enhance Throughput