In one embodiment a method includes selectively controlling a virtual network switch to control a quality of service (QoS) for a flow associated with a virtual machine (VM). Controlling the QoS may include controlling the virtual switch to provide classification, congestion management, congestion avoidance, bandwidth limiting, traffic shaping, and/or priority manipulation. The method may also include migrating a policy associated with a virtual interface between the VM and the virtual switch from a first server to a second server when the VM is to be migrated from the first server to the second server. The migration may also include moving statistics associated with the policy. The method may include selectively adapting the policy or an existing policy on the receiving server when a discrepancy is detected between the policies. The method may include reserving resources to provide guaranteed minimum bandwidth, even without control of an ingress and egress queue.