The network architecture of typical data centersis characterized bytiered networks andaggregation-based traffic controls.The emergence of big data makes it difficult for these data centers to incorporate big data service. The tier and aggregation based traffic management systems can magnify the seriousness of the traffic congestion and extend the congested region when big data moves around in the data center. As a consequence, big data has been forcing data centers to change their architecture dramatically. In this paper, we first address the important paradigm shifts of network architecture caused by big data traffic. We then show the new network architecture which resulted from our experience of the CERN LHC data service. Finally, we illustrate the effect of the throughput improvements of the proposed network architecture using a NS2simulation.