Testing the reachability of (new) address space

Abstract

The Internet was originally designed to provide connectivity from every node to every other node. However, policies can impede this connectivity [1]. This is especially true for newly allocated address space. Some Internet Service Providers (ISPs) simply do not realize that the status of previously unallocated address space has changed, and they continue blocking that space. Therefore, it would be desirable to test whether filters block newly apportioned address space before it is allocated to ISPs and/or end users. In this paper we present a methodology that aims to detect incorrectly configured filters, so that ISPs can be contacted and asked to update their router configurations. Our methodology is capable of detecting paths on which reachability is actually present but which are routed around an outdated filter configuration, as well as cases where a destination is inaccessible. To help narrowing down the most likely ASs that actually filter, we introduce a filtering likelihood index. We apply our methodology on newly allocated address space and perform initial experiments on a large fraction of ISPs, covering over 80% of all Autonomous Systems (ASs).