Joint Optimization of VNF Assignment and SFC Routing for Robust and Real-Time Symbiotic IoT Services
Pan Li, Songtao Guo, Yue Wu Zeng, Guiyan Liu · IEEE Internet of Things Journal · 2025
As a key enabler for 6G and symbiotic IoT applications, edge computing brings computing resources closer to end users, ensuring low-latency services, while network function virtualization (NFV) enables flexible service deployment by abstracting complex functionalities into service function chains (SFCs) composed of virtual network functions (VNFs). However, in dynamic edge environments, traffic changes and frequent network failures can lead to outdated routing configurations, resulting in load imbalance, network congestion, and Quality of Service (QoS) degradation. These issues will damage the robustness and real-time response capability required for symbiotic IoT systems. Although existing work separately optimizes VNF assignment or SFC routing for real-time and robust SFC updates, it fails to jointly optimize both, leading to potential VNF overload and throughput degradation. Therefore, this article studies the joint optimization of the VNF assignment and SFC routing problem, considering limited resource capacity, robustness and delay requirements, and bounded migration costs, aiming to maximize the network throughput. To capture all these characteristics, we formalize the problem as integer linear programming (ILP) and prove its NP-hardness. To tackle this problem, we propose a QoS-aware VNF assignment and routing update algorithm that first relaxes the ILP to linear programming (LP), and then randomly rounds the fractional solution obtained by solving LP to obtain a nearly optimal integer solution. Furthermore, we propose a backtracking-based greedy improvement algorithm, which greedily adjusts VNF assignments and request paths to accommodate more requests and satisfy all constraints. Extensive simulation results show that compared to state-of-the-art solutions, the proposed method can improve throughput by 22.98% while meeting user QoS.