Assessing co-locality of IP blocks
Many IP Geolocation services and applications assume that all IP addresses within the same /24 IPv4 prefix (a /24 block) reside in close physical proximity. For blocks that contain addresses in very different locations (such as blocks identifying network backbones), this assumption can result in a large geolocation error. In this paper we evaluate the co-location assumption. We first develop and validate a hierarchical clustering method to find clusters of IP addresses with similar observed delay measurements within /24 blocks. We validate our methodology against two ground-truth datasets, confirming that 93% of the identified multi-cluster blocks are true positives with multiple physical locations and an upper bound for false positives of only about 5.4%. We then apply our methodology to a large dataset of 1.41M /24 blocks extracted from a delay-measurement study of the entire responsive IPv4 address space. We find that about 247K (17%) out of 1.41M blocks are not co-located, thus quantifying the error in the /24 block co-location assumption.
Proceedings - IEEE INFOCOM
Gharaibeh, M., Zhang, H., Papadopoulos, C., & Heidemann, J. (2016). Assessing co-locality of IP blocks. Proceedings - IEEE INFOCOM, 2016-September, 503-508. https://doi.org/10.1109/INFCOMW.2016.7562129