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Observing Limited Visibility Prefixes in the Wild

18 Apr 2013, 16:00


15 Hatfields, Chadwick Court, London, SE1 8DJ


Mr Olaf Maennel (Loughborough University)


Advertising a prefix is only the first step towards achieving global reachability. However, filters and policies may not mean that an advertised prefix is reachable from everywhere on the Internet. We have build a tool, that looks at publicly available data and checks the global reachability of your prefixes. The output from our studies are available at Such limited visibility can have many different reasons, but we had some initial talks to operators and discovered many misconfiguration problem. We would like to turn this tool into a useful "BGP policy verification" system. In this talk we report on our findings of analysing many month of global routing table data, we find that there are about 100.000 prefixes that show limited visibility and about 3.000 prefixes which do not have any less specific prefix (e.g., which do not provide any connectivity at all).

Primary author

Mr Olaf Maennel (Loughborough University)

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