Towards QoS-aware Provisioning of Chained Virtual Security Services in Edge Networks

Future networks are expected to deliver low-latency, user-specific services in a flexible and efficient manner. Operators have to ensure infrastructure resilience in the face of such challenges, while maintaining service guarantees for subscribed users. One approach to support emerging use cases is through the introduction and user of virtualised network functions (VNFs) at the edge of the network. While placement of VNFs at the network edge has been previously studied, it has not taken into account services comprised of multiple VNFs and considerations for network security.In this paper we propose a mathematical model for latency-optimal on-path allocation of VNF chains on physical servers within an edge network infrastructure, with special considerations for network security applications and operator's best practices. We acknowledge the challenges of employing optimal solutions in real networks and provide the Minimal Path Deviation Allocation algorithm for placement of security-focused network services in a distributed edge environment, minimising end-to-end latency for users.We then evaluate our placement results over a simulated nation-wide network using real-world latency characteristics. We show that our placement algorithm provides near-optimal placement, with minimal latency violations with respect an optimal solution, whilst offering robust tolerance to temporal latency variations.