Virtual Network Function Forwarding Graph Design in IoT Networks

doi:10.3778/j.issn.1673-9418.2407089

Abstract

Abstract: In recent years, the rapid development of the Internet of things (IoT) and the explosive growth in the number of its terminals have imposed higher demands on IoT network services. Combined with network function virtualization (NFV) and software defined network (SDN) technology, the virtualization and softwarization of the new generation of IoT services can be represented as a virtual network function forwarding graph (VNF-FG). However, existing researches primarily focus on the VNF-FG embedding (VNF-FGE) problem, treating VNF-FG as a predetermined input and neglecting its design. Moreover, current VNF deployment algorithms often fail to fully leverage the graph structure of VNF-FG, resulting in certain limitations of these algorithms. To address these issues, this paper investigates the design of the VNF-FG directed acyclic graph (DAG). Given a set of service requests arriving at an IoT terminal, this paper first establishes constraints and formulates an integer linear programming (ILP) model to generate the optimal acyclic VNF-FG. Subsequently, this paper proposes a high-efficiency acyclic graph design algorithm that aims to minimize the total number of virtual nodes. This algorithm fully utilizes existing virtual nodes and identifies the key VNF instances that cause loops. By reversely expanding an appropriate number of key VNFs to eliminate loops in the VNF-FG, this paper achieves a balance between ensuring loop-free and minimizing the number of virtual nodes. Simulation results show that the difference between the proposed algorithm and the ILP model is minimal. Compared with other existing algorithms, the proposed method reduces the average number of virtual nodes generated by 17.67% for different service function chain (SFC) request quantities.

Key words: network function virtualization, Internet of things, integer linear programming, virtual network function forwarding graph

摘要： 近年来，物联网的迅速发展和其终端数量的爆炸式增长对物联网网络服务提出了更高要求。结合网络功能虚拟化（NFV）和软件定义网络（SDN）技术，对新一代物联网服务功能虚拟化和软件化，可以将网络服务表示为虚拟网络功能转发图（VNF-FG）。现有的研究主要关注VNF-FG嵌入（VNF-FGE）问题，把VNF-FG作为确定输入，忽略了VNF-FG的设计问题；又或者在设计VNF部署算法时，没有充分利用VNF-FG的图结构，使算法有一定局限性。因此，研究VNF-FG有向无环图（DAG）设计问题。针对一组到达物联网终端的服务请求，设计约束，建立一个整数线性规划（ILP）模型生成最优无环VNF-FG；以最小化虚拟节点总数为目标，提出一种高效的虚拟网络功能转发无环图设计算法，充分利用已有虚拟节点，并找出导致成环的关键VNF实例，通过反向增扩恰当数量的关键VNF以消除VNF-FG中的环路，在保证无环和最小化虚拟节点数量之间进行折中。实验结果表明，该算法与ILP模型之间的差距很小；与其他已有算法相比，在不同SFC请求数量下，该算法生成的虚拟节点个数平均降低了17.67%。

关键词: 网络功能虚拟化, 物联网, 整数线性规划, 虚拟网络功能转发图

REN Cheng, LIU Jing, WANG Yu, LI Yaxin, LI Hongwei. Virtual Network Function Forwarding Graph Design in IoT Networks[J]. Journal of Frontiers of Computer Science and Technology, 2025, 19(6): 1632-1639.

任诚, 刘静, 王宇, 李亚鑫, 李红伟. 物联网中虚拟网络功能转发图算法设计[J]. 计算机科学与探索, 2025, 19(6): 1632-1639.

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