Citrix's $500 million buyout of XenSource is a brilliant strategic move that will enable the Ft. Lauderdale, Fl. software company -and its powerful close ally, Microsoft — to steal market share from virtualization software kingpin VMware.

The data suggests a new picture of the AS-graph structure, which distinguishes a relatively large, redundantly connected core of nearly 100 ASes and two components that flow data in and out from this core. One component is fractally interconnected through peer links; the second makes direct connections to the core only. The model which results has superficial similarities with and important differences from the "Jellyfish" structure proposed by Tauro et al., so we call it a "Medusa."