A multi-criteria decision approach for minimizing the influence of VNF migration

Network Function Virtualization (NFV) has been proposed as an important paradigm to speed up the service deployment and provision, by decoupling network functionalities from the underlying hardware. These network functionalities are implemented as software that refers to as Virtual Network Function (VNF) and managed under the software defined networking environment. Thus, VNFs are critical elements for service provision. However, in order to achieve a better service deployment and provision, VNF migration is a key challenge to be addressed. On one hand, previous researches resolving the VNF migration problem are under the assumption that each VNF is independently used by one Service Function Chain (SFC) which is actually composed of a sequential set of VNFs with traffic traversing these VNFs in order. In this way, they only need to consider one SFC when fulfilling the VNF migration. In contrast, we assume that each deployed VNF may be used by different services. Thus, when migrating one VNF, we take all the services traversing this VNF into consideration, which is more practical and meaningful. On the other hand, the VNF migration is primarily transferring the internal stateful information of VNFs, which is fast. Therefore, instead of focusing on the migration process, we prefer more to minimize the influence on services after executing the VNF migration. In this paper, we first formulate the VNF migration problem as a mathematical model with the objective of minimizing the influences. Then, a multi-criteria approach is proposed to address this problem, since we need to consider multiple services simultaneously. In particular, the service priority is also considered in the proposed approach in order to meet the practical situations. Finally, the simulation results indicate that the proposed approach is effective and efficient. (C) 2019 Published by Elsevier B.V.