Software Defined Networking (SDN) concepts are seen as suitable enablers for network virtualization, especially in the Data Center Network domain. However, also carrier network operators can benefit from network virtualization, since it allows new business models, promising economical benefits through sharing the cost of network infrastructure in e.g. multi-tenancy or service-isolation scenarios. Such use-cases pose additional requirements on virtualization schemes, including strict performance and information isolation, transparency of the virtualization system, high availability, as well as low CAPEX and OPEX demands. In order to fulfill these requirements, we previously proposed a flexible virtualization scheme for OpenFlow. In this paper we discuss the implementation of the proposed scheme and point out relevant lessons learned during the process, leading to architectural and technological updates. We then evaluate the system in terms of data path performance: the impact on forwarding latency is negligible, while the impact on network throughput is depending on the type of traffic and the choice of encapsulation technology. In summary, the overhead can be kept small and would not significantly affect a production network. Thus, we conclude that the minor performance degradations are outweighed by the benefits of the virtualization system.