Resilient Placement of Network Functions in a WMN-Based NFV Infrastructure

A Wireless Mesh Network (WMN)-based disaster network integrates Network Function Virtualisation (NFV) for dynamic service provisioning by utilising node hardware to establish an NFV infrastructure (NFVI). This NFVI provides two kinds of network functions: virtual network functions (VNFs) to enable required network services and distributed Management and Orchestration (MANO) components to manage and orchestrate the NFVI and its resources. The network infrastructure faces challenges such as node and link failures and end-user movement, potentially leading to network function loss, connectivity issues, or even network partitions and traffic congestion. This publication proposes a resilient placement concept for the network functions required in the WMN-based NFVI, improving their resilience regarding the possible challenges. The concept enforces a geo-distributed redundant deployment of the network functions based on the end-user positions and different connectivity metrics, including node-individual connectivity and the overall network connectivity, including potentially existing network partitions. Simulations using an Integer Linear Programming (ILP)-based optimisation objective show that the concept significantly decreases the likelihood of losing a network function instance to a network partition, reducing this overall probability by up to 30% compared to a performance-based placement approach and by up to 50% compared to a random-based approach. At the same time, it only slightly increases the traffic load in the network, with the average hop-count increasing by just 0.5 compared to performance-based placement.