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Reliable Placement of Service Function Chains and Virtual Monitoring Functions With Minimal Cost in Softwarized 5G Networks

Network Functions Virtualization (NFV) allows softwarization of network functions and enables to run network functions as Virtual Network Function (VNF) instances on top of the cloud infrastructure. In softwarized 5G networks, communication services can be realized through Service Function Chains (SFCs) in which multiple VNFs are connected in a sequential order as per the requirements, which offer flexibility, agility, and dynamic management and orchestration of networks. However, softwarization and cloudification of networks using NFV introduce new challenges in terms of reliability and availability due to software bugs, hardware failures, malfunction of VNFs, and service degradation. In this article, we first explore latency-aware and reliable SFC placement to meet the requirements of users and enhance the reliability of SFCs from VNF failures. Then, we focus on reliable placement of virtual monitoring functions at proximal locations of VNFs in order to identify and mitigate service degradation and security-related issues in the network. To this end, we formulate the problems as Integer Linear Programming (ILP) problems to minimize the total deployment cost, and show that they are NP-hard. To overcome the high computational complexity of the ILP problems, we propose novel heuristic algorithms based on complex network theory to provide near-optimal solutions in polynomial time for large input instances. By extensive simulations, we show that our proposed algorithms provide near-optimal solution (optimality gap is 5%) in a real-world network topology.