Effective NFV Orchestration for Wide-Ranging Services Across Heterogeneous Cloud Networks

In the Network Functions Virtualization (NFV) environment, to successfully orchestrate a network service, first a Virtual Network Function-Forwarding Graph (VNF-FG) must be composed that realizes the required functionality. Second, this VNF-FG must be embedded onto the infrastructure, that is increasingly becoming heterogeneous. To avoid wasting precious resources during orchestration, intelligent resource allocation mechanisms and algorithms are needed to effectively tailor the VNF-FG to the cloud network onto which the service will be deployed. In this paper, we introduce an improved service model supporting network services that have bidirectional chaining constraints, comprise optional VNFs, and require traffic aggregation. Building on this service model, we propose placement algorithms that can optimize the order and number of instances of VNFs, to adapt the VNF-FG to the availability of resources in the network. Numerical experiments show that through coordination of composition and embedding tasks, our proposed algorithms can significantly improve the acceptance ratio, compared to algorithms that perform these tasks in two separate stages.