The Internet, undoubtedly, is the most influential\ud
technical invention of the 20th century\ud
that affects and constantly changes all aspects\ud
of our day-to-day lives nowadays. Although it\ud
is hard to predict its long-term consequences,\ud
the potential future of the Internet definitely\ud
relies on future Internet research. Prior to\ud
every development and deployment project, an\ud
extensive and comprehensive research study\ud
must be performed in order to design, model,\ud
analyze, and evaluate all impacts of the new\ud
initiative on the existing environment. Taking\ud
the ever-growing size of the Internet and the\ud
increasing complexity of novel Internet-based\ud
applications and services into account, the\ud
evaluation and validation of new ideas cannot\ud
be effectively carried out over local test beds\ud
and small experimental networks. The gap\ud
which exists between the small-scale pilots in\ud
academic and research test beds and the realsize\ud
validations and actual deployments in production\ud
networks can be bridged by using\ud
virtual infrastructures. FEDERICA is one of\ud
the facilities, based on virtualization capabilities\ud
in both network and computing resources,\ud
which creates custom-made virtual environments\ud
and makes them available for Future\ud
Internet Researchers. This article provides a\ud
comprehensive overview of the state-of-the-art\ud
research projects that have been using the virtual\ud
infrastructure slices of FEDERICA in\ud
order to validate their research concepts, even\ud
when they are disruptive to the test bed’s infrastructure,\ud
to obtain results in realistic network\ud
environments.Postprint (published version