Shortest Path Tour Problem Based Integer Linear Programming for Service Chaining in NFV Networks

Network functions virtualization (NFV) is a new paradigm to achieve flexible and agile network services by decoupling network functions from proprietary hardware and running them on generic hardware as virtual network functions (VNFs). In the NFV network, a certain network service can be modeled as a sequence of VNFs, called a service chain. Given a connection request (origin node, destination node, and service chain requirement, which is a sequence of functions), the service chaining problem aims to find an appropriate service path, which starts from the origin and ends with the destination while executing the VNFs at the intermediate nodes in the required order. Some existing work noticed that the service chaining problem was similar to the shortest path tour problem (SPTP). To the best of our knowledge, this is the first work that exactly formulates the service chaining problem as an SPTP-based integer linear program (ILP). Through numerical results, we show the SPTP-based ILP can support 1.30-1.77 times larger scale systems than the existing ILP.