Mobile communication is increasingly oriented towards the usage of all IP networks as fixed-network components. An open problem is how to provide QoS guarantees that are competitive with that of existing cellular networks. In particular, an appropriate handover support is missing: a handover should not be performed to a base station that is not able to support the desired QoS. This paper presents a performance evaluation of a mechanism that integrates QoS support and handover mechanisms in IP networks such that a handover is conditionalized upon availability of sufficient QoS resources. We show that this scheme is able to efficiently provide such conditional handover support, that it is competitive with standard Hierarchical Mobile IPv6 regarding the amount of carried traffic, and that it outperforms Hierarchical Mobile IPv6 in arranging traffic within the network, resulting in a superior efficiency especially for mixed QoS/non-QoS traffic.