  Fog computing extends the cloud to the edge of the network, close to the
end-users enabling the deployment of some application component in the fog
while others in the cloud. Network Functions Virtualization (NFV) decouples the
network functions from the underlying hardware. In NFV settings, application
components can be implemented as sets of Virtual Network Functions (VNFs)
chained in specific order representing VNF-Forwarding Graphs (VNF-FG). Many
studies have been carried out to map the VNF-FGs to cloud systems. However, in
hybrid cloud/fog systems, an additional challenge arises. The mobility of fog
nodes may cause high latency as the distance between the end-users and the
nodes hosting the components increases. This may not be tolerable for some
applications. In such cases, a prominent solution is to migrate application
components to a closer fog node. This paper focuses on application component
migration in NFV-based hybrid cloud/fog systems. The objective is to minimize
the aggregated makespan of the applications. The problem is modeled
mathematically, and a heuristic is proposed to find the sub-optimal solution in
an acceptable time. The heuristic aims at finding the optimal fog node in each
time-slot considering a pre-knowledge of the mobility models of the fog nodes.
The experiment's results show that our proposed solution improves the makespan
and the number of migrations compared to random migration and No-migration.
