Measuring Multipath Routing in the Internet

Tools to measure Internet properties usually assume the existence of just one single path from a source to a destination. However, load-balancing capabilities, which create multiple active paths between two end-hosts, are available in most contemporary routers. This paper extends Paris trace route and proposes an extensive characterization of multipath routing in the Internet. We use Paris traceroute from RON and PlanetLab nodes to collect various datasets in 2007 and 2009. Our results show that the traditional concept of a single network path between hosts no longer holds. For instance, 39% of the source-destination pairs in our 2007 traces traverse a load balancer. This fraction increases to 72% if we consider the paths between a source and a destination network. In 2009, we notice a consolidation of per-flow and per-destination techniques and confirm that per-packet load balancing is rare.