1. An apparatus, comprising: a plurality of virtual machines operating within a virtual environment; a plurality of unified virtual network interface instances included within a plurality of operating systems of said plurality of virtual machines and providing a plurality of device specific network capabilities comprising network connectivity and quality of service requirements including network bandwidth allocation requirements for said plurality of virtual machines; a plurality of network capability provider instances operating within an operating system of a host system and interfacing with said plurality of unified virtual network interface instances in paired relationships to provide said plurality of device specific network capabilities for said plurality of virtual machines through said host system; and a network capability provider comprising said plurality of network capability provider instances for enforcing sharing of host-wide network bandwidth based on said quality of service requirements of said plurality of unified virtual network interface instances as implemented through said plurality of unified virtual network interfaces supported by said host system; wherein a network capability provider instance comprises a 4-tuple data structure comprising an identifier holder for holding a unique identifier of a corresponding unified virtual network interface instance; a configurable network connectivity provided for a corresponding virtual machine by said host system; a services capability provided for said virtual machine; and properties of an underlying hardware resource provided said host-wide network capability.