Is it a Real CD Mismatch in Interdomain Routing?

Abstract: In inter-domain routing, a packet is not always forwarded along the Autonomous System (AS) level path determined by the BGP routing protocol. This is often called control-plane and data-plane (CD) mismatch, which allows for flexible traffic control, but also leads to operation and security issues. We systematically analyze this phenomenon with path pairs collected from 128 pairs of vantage points over more than 5 years, and use multiple IP-to-AS mapping methods to compare CD paths. What is interesting is that, working at such a large scale in turn helps us design a novel method to fairly evaluate the accuracy of various existing mapping methods, and further develop a new mapping method, i.e., LearnToCorrect, that can correct more than 70\% mapping errors of the state-of-the-art one. Then we devise to identify real mismatches with LearnToCorrect, and estimate that the real-mismatch ratio in the wild is typically less than 6\%. At last, we use our proposed methods to detect routing security issues, which are previously difficult to accurately find out.