During the last few years, more and more of the medium-to-large Internet
eXchange Points (IXP) around the world have started to operate a route
server and offer its use as a free value-added service to their members. This
service has greatly simplified inter-domain routing for those members and has
made it easy for them to peer with possibly hundreds of networks at those IXPs
from the get-go.
In this paper, we report on an empirical analysis that is based on a unique collection of IXP-provided datasets from two different European IXPs that operate a route server and gave us access to a wealth of route server-specific BGP data. Both IXPs also made the traffic datasets that they routinely collect from their public switching infrastructures available to us. Using this information, we perform a first-of-its-kind study that correlates a detailed control plane view with a rich data plane view to reason about the different peering options available at these IXPs and how some of the major Internet players make use of them. In the process, we highlight the important role that the IXPs' route servers play for inter-domain routing in today's Internet and demonstrate the benefits of studying IXP peerings in a manner that is not agnostic but fully aware of traffic. We conclude with a discussion of some of the ramifications of our findings for both network researchers and operators.