A method implemented to provide a virtual network to tenants requiring bandwidth in a cloud computing environment is disclosed. The method starts with receiving a request for a task at a network device, the request including a first parameter indicating VMs required, a second parameter indicating bandwidths the required VMs need, a third parameter indicating a duration of the task, and a fourth parameter indicating a deadline of the task. The network device then selects a starting time and a bandwidth allocation of the task, where the bandwidth allocation is shrank to be smaller than the second parameter indicating, and where the selection aims at minimizing a measurement of cloud resource utilization considering consumptions of both VMs and bandwidth. Then the network device allocates VMs for the request at the starting time with the bandwidth allocated at a particular location in the cloud computing environment.