Efficient solutions to the placement and chaining problem of User Plane Functions in 5G Networks

This study attempts to solve the placement and chaining problem of 5G User Plane Functions (UPFs) in a Multi-access Edge Computing (MEC) ecosystem. The problem is formalized as a multi-objective Integer Linear Programming (ILP) model targeted at optimizing provisioning costs and quality of service. Our model takes into account several aspects of the system such as UPF-specific considerations, the Service Function Chain (SFC) requests topology (single and multiple branches), Virtual Network Function (VNF) order constraints, service demands, and physical network capacities. Since the formulated problem is NP-hard, two heuristic solutions are devised to enhance solution efficiency. Specifically, an algorithm called Priority and Cautious-UPF Placement and Chaining (PC-UPC) and a simulated annealing (SA) meta-heuristic are proposed. Through extensive simulation experiments, we evaluated the performance of the proposed solutions. The results revealed that our solutions outperformed the baselines (i.e., two greedy-based heuristics and a variant of the classical SA) and that we had obtained nearly optimal solutions with significant reductions in running time. Moreover, the PC-UPC algorithm can effectively avoid SFC rejections and improve provisioning costs by considering session requirements, current network conditions, and the effects of VNF mapping decisions. Additionally, the proposed SA approach incorporates several mechanisms (e.g., variable Markov chain length and restart–stop) that allow the improvement of not only the quality of the solutions but also their computation time.Postprint (published version

Minimum-Cost Virtual Network Function Resilience

International audienceIn the future 5G networks, a wide range of new services with strong requirements will be delivered in the form of chains of service functions on independent virtual networks. These virtual networks will be deployed on demand, each one adapted to the specific service requirements. For infrastructure providers a real challenge consists in providing and setting up the required virtual networks (network slices) while guaranteeing strict Service Level Agreements. One of the major stakes is to be able to provide failure protection for the service function chains at minimal cost. In this work, we consider a set of deployed service chains, and we study the best strategy to protect them at minimal cost. We propose mathematical formulations that provide optimal backup functions placement over a network, and the associated backup paths for each VNF of all the chains. We develop an efficient ILP-based heuristic relying on a separation of the problem into smaller ones to solve large scale instances. We show that our heuristic is competitive, both regarding the solution quality and the solving time

Virtual Network Function Placement for Service Chaining by Relaxing Visit Order and Non-Loop Constraints

Network Function Virtualization (NFV) is a paradigm that virtualizes traditional network functions and instantiates Virtual Network Functions (VNFs) as software instances separate from hardware appliances. Service Chaining (SC), seen as one of the major NFV use cases, provides customized services to users by concatenating VNFs. A VNF placement model for SC that relaxes the visit order constraints of requested VNFs has been considered. Relaxing the VNF visit order constraints reduces the number of VNFs which need to be placed in the network. However, since the model does not permit any loop within an SC path, the efficiency of utilization of computation resources deteriorates in some topologies. This paper proposes a VNF placement model for SC which minimizes the cost for placing VNFs and utilizing link capacity while allowing both relaxation of VNF visit order constraints and configuration of SC paths including loops. The proposed model determines routes of requested SC paths, which can have loops, by introducing a logical layered network generated from an original physical network. This model is formulated as an Integer Linear Programming (ILP) problem. A heuristic algorithm is introduced for the case that the ILP problem is not tractable. Simulation results show that the proposed model provides SC paths with smaller cost compared to the conventional model

Availability Evaluation of Service Function Chains Under Different Protection Schemes

Network Function Virtualization (NFV) calls for a new resource management approach where virtualized network functions (VNFs) replace traditional network hardware appliances. Thanks to NFV, operators are given a much greater flexibility, as these VNFs can be deployed as virtual nodes and chained together to form Service Function Chains (SFCs). An SFC represents a set of dedicated virtualized resources deployed to provide a certain service to the consumer. One of its most important performance requirements is availability. In this paper, the availability achieved by SFCs is evaluated analytically, by modelling several protection schemes and given different availability values for the network components. The cost of each protection scheme, based on its network resource consumption, is also taken into account. Extensive numerical results are reported, considering various SFC characteristics, such as availability requirements, number of NFV nodes and availability values of network components. The lowest-cost protection strategy, in terms of number of occupied network components, which meets availability requirement, is identified. Our analysis demonstrates that, in most cases, resource-greedy protection schemes, such as end-to-end protection, can be replaced by less aggressive schemes, even when availability requirements are in the order of five or six nines, depending on the number of elements in the service function chain

A Study on Efficient Service Function Chain Placement in Network Function Virtualization Environment

電気通信大学202

A New Approach for Delivering Customized Security Everywhere: Security Service Chain

Security functions are usually deployed on proprietary hardware, which makes the delivery of security service inflexible and of high cost. Emerging technologies such as software-defined networking and network function virtualization go in the direction of executing functions as software components in virtual machines or containers provisioned in standard hardware resources. They enable network to provide customized security service by deploying Security Service Chain (SSC), which refers to steering flow through multiple security functions in a particular order specified by individual user or application. However, SSC Deployment Problem (SSC-DP) needs to be solved. It is a challenging problem for various reasons, such as the heterogeneity of instances in terms of service capacity and resource demand. In this paper, we propose an SSC-based approach to deliver security service to users without worrying about physical locations of security functions. For SSC-DP, we present a three-phase method to solve it while optimizing network and security resource allocation. The presented method allows network to serve a large number of flows and minimizes the latency seen by flows. Comparative experiments on the fat-tree and Waxman topologies show that our method performs better than other heuristics under a wide range of network conditions

Preface: Recent advances in telecommunications networks planning and operation

International audienc

Virtual network function placement and routing for multicast service chaining using merged paths

This paper proposes a virtual network function placement and routing model for multicast service chaining based on merging multiple service paths (MSC-M). The multicast service chaining (MSC) is used for providing a network-virtualization based multicast service. The MSC sets up a multicast path, which connects a source node and multiple destination nodes. Virtual network functions (VNFs) are placed on the path so that users on the destination nodes receive their desired services. The conventional MSC model configures multicast paths for services, each of which has the same source data and the same set of VNFs in a predefined order. In the MSC-M model, if paths of different services carry the same data on the same link, these paths are allowed to be merged into one path at that link, which improves the utilization of network resources. The MSC-M model determines the placement of VNFs and the route of paths so that the total cost associated with VNF placement and link usage is minimized. The MSC-M model is formulated as an integer linear programming (ILP) Problem. We prove that the decision version of VNF placement and routing problem based on the MSC-M model is NP-complete. A heuristic algorithm is introduced for the case that the ILP problem is intractable. Numerical results show that the MSC-M model reduces the total cost required to accommodate service chaining requests compared to the conventional MSC model. We discuss directions for extending the MSC-M model to an optical domain