Most recently much effort has been made to address Internet "ossification" by exploiting network virtualization technique. It allows multiple virtual networks to share the physical substrate for delivering customized services via heterogenous protocols or mechanisms. Recent advances enable virtual routers to flexibly migrate across multiple physical routers without interrupting network operation. With this recognition, this paper takes a further step by proposing a novel algorithmic approach to optimize network load balancing as well as resource utilization. The suggested approach is assessed through extensive simulation experiments against two other algorithmic solutions for a range of network scenarios (e:g. dense and sparse networks). The numerical result shows its effectiveness in providing the best trade-off of network load balancing and resource utilization whilst minimizing the communication overheads.