John Heidemann

Assessing Co-Locality of IP Blocks

TitleAssessing Co-Locality of IP Blocks
Publication TypeTechnical Report
Year of Publication2015
AuthorsM. Gharaibeh, H. Zhang, C. Papadopoulos, and J. Heidemann
Date Publishednov

Many IP Geolocation services and applications assume that all IP addresses with the same /24 IPv4 prefix (a \emph/24 block) are in the same location. For blocks that contain addresses in very different locations (such blocks identifying network backbones), this assumption can result in large geolocation error. This paper evaluates this assumption using a large dataset of 1.41M /24 blocks extracted from a delay measurements dataset for the entire responsive IPv4 address space. We use hierarchal clustering to find clusters of IP addresses with similar observed delay measurements within /24 blocks. Blocks with multiple clusters often span different geographic locations. We evaluate this claim against two ground-truth datasets, confirming that 93% of identified multi-cluster blocks are true positives with multiple locations, while only 13% of blocks identified as single-cluster appear to be multi-location in ground truth. Applying the clustering process to the whole dataset suggests that about 17% (247K) of blocks are likely multi-location.