Reality shock in virtual network embedding: Flexibilizing demands for dealing with multiple operational requirements in SDNs.

Network virtualization and Software-Defined Networking (SDN) are both promising techniques that allow administrators to deal with the complexity and dynamic requirements of today's networks. Moreover, SDN provides a favorable environment for instantiating and hosting virtual networks. An essential component of this paradigm consists of properly mapping requested virtual resources to physical infrastructures – a problem that is considered NP-hard (Yu et al., 2008), known as Virtual Network Embedding (VNE). Despite the existence of a large body of work in the area of VNE, existing approaches tend to neglect operational requirements crucial for the instantiation of VNs on specific platforms, limiting their scope to generic VN requirements. In this paper, we propose a VNE approach that encompasses a wide set of operational requirements related to SDN-based network virtualization platforms. Moreover, we tackle the issue of solution space reduction – which emerges as a consequence of handling a large number of constraints simultaneously – by means of a constraint flexibilization strategy. Through a comprehensive evaluation, we demonstrate that the proposed approach is capable of optimally embedding incoming requests in a time frame limited to the order of seconds while successfully mitigating losses in terms of acceptance rates – a direct consequence of the aforementioned solution space reduction. The main contribution of this work lies in devising an efficient strategy for coping with a combination of numerous operational requirements while ensuring infrastructure resources are properly used.