  Network functions virtualization (NFV) is a new concept that has received the
attention of both researchers and network providers. NFV decouples network
functions from specialized hardware devices and virtualizes these network
functions as software instances called virtualized network functions (VNFs).
NFV leads to various benefits, including more flexibility, high resource
utilization, and easy upgrades and maintenances. Despite recent works in this
field, placement and chaining of VNFs need more attention. More specifically,
some of the existing works have considered only the placement of VNFs and
ignored the chaining part. So, they have not provided an integrated view of
host or bandwidth resources and propagation delay of paths. In this paper, we
solve the VNF placement and chaining problem as an optimization problem based
on the particle swarm optimization (PSO) algorithm. Our goal is to minimize the
required number of used servers, the average propagation delay of paths, and
the average utilization of links while meeting network demands and constraints.
Based on the obtained results, the algorithm proposed in this study can find
feasible and high-quality solutions.
