Lessons from Three Views of the Internet Topology

TL;DR

This paper analyzes Internet AS-level topologies from three data sources, revealing differences and similarities, and emphasizes the importance of joint degree distribution in characterizing topologies, while providing datasets and tools for validation.

Contribution

It compares three common data sources for Internet topology, introduces an evaluation criterion for topology generators, and releases datasets and tools for community use.

Findings

Traceroute and BGP topologies are similar but differ from WHOIS.

Joint degree distribution characterizes key topology properties.

Generators reproducing degree distributions alone are insufficient.

Abstract

Network topology plays a vital role in understanding the performance of network applications and protocols. Thus, recently there has been tremendous interest in generating realistic network topologies. Such work must begin with an understanding of existing network topologies, which today typically consists of a relatively small number of data sources. In this paper, we calculate an extensive set of important characteristics of Internet AS-level topologies extracted from the three data sources most frequently used by the research community: traceroutes, BGP, and WHOIS. We find that traceroute and BGP topologies are similar to one another but differ substantially from the WHOIS topology. We discuss the interplay between the properties of the data sources that result from specific data collection mechanisms and the resulting topology views. We find that, among metrics widely considered, the joint degree distribution appears to fundamentally characterize Internet AS-topologies: it narrowly defines values for other important metrics. We also introduce an evaluation criteria for the accuracy of topology generators and verify previous observations that generators solely reproducing degree distributions cannot capture the full spectrum of critical topological characteristics of any of the three topologies. Finally, we release to the community the input topology datasets, along with the scripts and output of our calculations. This supplement should enable researchers to validate their models against real data and to make more informed selection of topology data sources for their specific needs.