Coordinated Resource Allocation with VNFs Precedence Constraints in Inter-Datacenter Networks over Elastic Optical Infrastructure

For efficiently solving the problem of the special resource allocation in network function virtualization (NFV) scenarios with virtualized network functions (VNFs) precedence constraints, we formulate such a problem as an integer linear programming (ILP) model and propose a novel mechanism to both build and map the service function chain (SFC) with a coordinated method in inter-datacenter networks over elastic optical infrastructure. We design the VNFs reusing and deploying mechanism that is based on the bandwidth change ratio of each request. In the coordinated chaining and mapping algorithm (CCMA) proposed, both reducing the bandwidth consumption and reusing the deployed VNF instances are considered jointly. Simulation results show that the proposed CCMA could reduce the average cost significantly when compared with the existing uncoordinated methods.