1. A method comprising: determining overlay network attributes (ONAs) for a plurality of virtual networks, wherein the ONAs comprise a network identifier and tunnel information; associating the ONAs with the plurality of virtual networks; managing the ONAs as one or more portable entities by creating ONAs, deleting ONAs, moving ONAs, combining ONAs and dividing ONAs; and performing a movement operation comprising re-assigning the plurality of virtual networks to servers of overlay networks based on the management of the ONAs.