Diagnosing the Location of Bogon Filters
Speakers: Randy Bush, IIJ
We describe a methodology which targets the identification of wrongly configured route filters by Internet Service Providers (ISPs). A current problem for network operators is that newly announced IP address space (from previously unused IP blocks) is often not reachable as it is still blocked by certain ISPs. It is common for network operators to filter out address space which is known to be unallocated (bogon addresses). However, as allocated address space changes over time these bogons might become legitimately announced prefixes. Unfortunately, some ISPs still do not configure their bogon filters via lists published by the RIRs, instead choosing to manually configure filters. Therefore it would be desirable to test whether filters block IP blocks, before this address space is allocated to ISPs and/or end users. In this article we present a methodology that detects where wrongly configured filters exists, so that ISPs can be contacted and asked to update their filters.
See more at: https://www.nanog.org/meetings/nanog4...