1. A method of performing live migration of a virtual machine that is executing at a source site to a destination site over an optical network, the method comprising: executing an application program on the virtual machine on behalf of a client system, during which execution the client system maintains communication with the virtual machine and the application program; dynamically establishing a lightpath through the optical network between the source site and the destination site; while the application program continues to execute on the virtual machine, transferring a copy of the virtual machine over the acquired lightpath from the source site to the destination site; and resuming execution of the application program at the destination site, after the virtual machine is copied from the source site to the destination site.