On the stability and diversity of Internet routes in the MPLS era

Stability and diversity of end-to-end routes are key properties of Internet that have a large effect on the design of networks and networked systems. As the Internet evolves and deploys new technologies, it is important to re-assess these properties in the face of the new realities. This paper evaluates the stability and diversity of Internet routes with emphasis on the impact of the widely deployed Multi-Protocol Label Switching (MPLS). In particular, we analyze two data sets: (1) high frequency (once per minute) traceroutes originating from a number of PlanetLab hosts to a set of destinations distributed around the Internet (random hosts extracted from the Alexa list of top-1M websites), and (2) traceroutes originating from a large number of Ripe Atlas probes to a number of hosts (mostly root DNS servers). We find that Internet routes are significantly less stable than previously reported, at least according to one common metric (the route persistence), and much more diverse. At the same time, these more frequent route changes do not translate to high variability of route-trip time (RTT) delays between hosts, as RTTs tend to stay similar across route changes. Notably, with regard to diversity, we show that higher diversity is likely due not to a real change in the Internet but rather to underestimation by previous studies. Finally, our assessment of MPLS role in increased path instability produced inconclusive results as MPLS appears to be a significant contributor in the Ripe Atlas data set but not in the Planet Lab data set.