Characterizing Large-Scale Routing Anomalies: A Case Study of the China Telecom Incident

China Telecom’s hijack of approximately 50,000 IP prefixes in April 2010 highlights the potential for traffic interception on the Internet. Indeed, the sensitive nature of the hijacked prefixes, including US government agencies, garnered a great deal of attention and highlights the importance of being able to characterize such incidents after they occur. We use the China Telecom incident as a case study, to understand (1) what can be learned about large-scale routing anomalies using public data sets, and (2) what types of data should be collected to diagnose routing anomalies in the future. We develop a methodology for inferring which prefixes may be impacted by traffic interception using only control-plane data and validate our technique using data-plane traces. The key findings of our study of the China Telecom incident are: (1) The geographic distribution of announced prefixes is similar to the global distribution with a tendency towards prefixes registered in the Asia-Pacific region, (2) there is little evidence for subprefix hijacking which supports the hypothesis that this incident was likely a leak of existing routes, and (3) by preferring customer routes, providers inadvertently enabled interception of their customer’s traffic.