Online Monitoring of TCP Throughput Limitations

Monitoring and optimizing network performance is essential for data center operators and service providers. To better understand network performance, the throughput limiting factor of TCP connections can be analyzed. Previous research introduces approaches for the offline analysis of root causes of TCP throughput based on previously captured traffic. With increasing computational power and packet processing capabilities on commodity hardware, previously existing analysis limitations get overcome nowadays.This paper presents a scalable tool to analyze the throughput limitation of TCP flows in real-time, i.e., while the tool observes traffic on a network interface. We describe the adaption of existing approaches for TCP throughput limitation analysis and required passive capacity estimation to satisfy online analysis requirements.We evaluate the effectiveness and accuracy of our implementation with a generated data set for different TCP congestion control algorithms and varying network parameters. Furthermore, we survey the performance of our implementation with thousands of concurrent flows and discuss trade-offs and limitations of such sophisticated analysis in real-time.We provide our code as free and open-source.