This document discusses several technologies for building flexible data center fabrics including FabricPath/TRILL, VXLAN, LISP, and OTV. It provides an overview of the goals of the data center fabric including addressing workload mobility, scalability, and high availability. It also summarizes some of the key capabilities and advantages of technologies like FabricPath, VXLAN, LISP, and OTV for building flexible intra- and inter-DC fabrics.