Next Generation Networks (NGN) will be based upon the "all IP" paradigm. The IP protocol will glue multiple technologies, for both access and core networks, in a common and scalable framework that will provide seamless communication mobility not only across those technologies, but also across different network operators. In this article we describe a framework for QoS support in such NGNs, where multi-interface terminals are given end-to-end QoS guarantees regardless of their point of attachment. The framework supports media independent handovers, triggered either by the user or by the network, to optimize network resources' distribution. The framework integrates layer two and layer three handovers by exploiting minimal additions to existing IETF and IEEE standards.