Hybrid networks: lessons learned and future challenges based on ESnet4 experience

ESnet, the Energy Sciences Network, has the mission of providing the network infrastructure to the U.S. Department of Energy´s Office of Science programs and facilities, which depend on large collaborations and large-scale data sharing, enabling them to accomplish their science. ESnet4 - a hybrid IP and dynamic circuit network designed in 2006 and completed in 2008 - has managed to effectively satisfy the networking needs of the science community, easily handling dramatic growth in traffic requirements: around 80 percent growth year over year and 300 percent growth with the Large Hadron Collider (LHC) coming online. In this article, we examine the benefits and limitations of the current hybrid architecture based on actual production experience; discuss open research problems; and predict factors that will drive the evolution of hybrid networks, including advances in network technology, new computer architectures, and the onset of large-scale distributed computing.