On the characteristics of BGP multiple origin AS conflicts

The Internet has thousands of autonomous systems (ASs), each advertising one or more prefixes it owns. According to RFC 1930, each prefix should originate from a single AS. However, routing updates involving multiple ASs advertising reachability to a given prefix, so called multiple origin AS conflict (MOAS), are becoming prevalent. To this end, this paper analyzes and quantifies MOAS conflicts observed in routing updates collected over 21 days in January 2007, and presents ten reasons that explain why they occur.