# Software-Defined Vehicular Cloud Networks: Architecture, Applications and Virtual Machine Migration
## 4 Migration Management of VM over SDVC
### Review of the State-of-the-Art of VM Migration Techniques over SDVC
#### 4.2.2 Simulation Tools for VM Migration Services over SDVC  
The SD-based vehicular cloud still lacks real simulation environment tools to better evaluate the performance of management of VM migration. The Mininet-WiFi [54] lacks cloud-based functions to ensure the simulation of VM migration. The work in [36] proposes a base foundation for the design and implementation of an SDVN-based cloud simulator. In addition, mobility in the vehicular network affects the migration of VM. Therefore, SDVN-based cloud simulator and existing traffic simulator such as Simulation for Urban Mobility (SUMO) [55] would support the evaluation of VM strategies in SDVC. The SDN-based cloud simulator integrated with traffic mobility of vehicle nodes is addressed as research directions for future works. Most SDVN enabled edge/cloud computation methods address the issue of resource management to ensure higher network performance. Multi-access edge computing would address the issue of management of VM Migration (VMM) in order to allow VM to resume themselves. Simulator tools for the cloud network model based SDN controller are proposed in [56; 57]. These simulator tools only support simulations scenarios for fixed cloud SDN-controller networks and usually run single- or multi-VM hosts. A survey on simulation evaluation of network model software-defined vehicular based edge (fog) and cloud computing network model is given in Table 2. The migration of VM is performed for keeping the computation service deployed at either edge or cloud computing infrastructure. Mininet-WiFi [54] and OMNeT++ [58] integrated with Simulation for Urban Mobility (SUMO) [55] are the most currently used to evaluate the performance of SD-basedvehicular cloud system. Mininet-WiFi is an extension of the Mininet [59] emulator to simulate a mobile wireless node. SUMO is used to inject traffic mobility to allow Mininet-WiFi to evaluate SDVN architecture [45; 52]. However, the Mininet-WiFi platform lacks the ability to apply VM migration technologies. A third platform to evaluate VM migration was developed by [PERSON] et al. [36]. The platform in [36] evaluates cloud-based applications but does not propose a new approach for the migration of VM. It is clear that a platform for cloud and virtualization concepts integrated to Mininet-WiFi is needed. Part of Mininet-WiFi, the OMNeT++ network, evaluates a SDVN-based edge computing in [47]. OMNeT++ [58] has modules to emulate cloud computation particularly for realistic VM migration simulations environments. Accordingly, the emulator platform that evaluates smart cloud applications [36] should be extended with a traffic mobility interface to improve the simulation evaluation of SD-based vehicular cloud applications. The lack of an SDN-based vehicular cloud simulator limits the performance of the control plane in the SDVN system. Table 2 shows that most SD-based vehicular and edge cloud computing concentrates on mathematical analysis rather than to realistic simulation environments. A vehicular edge/fog computing to support the control layer over SDVN for content delivery is discussed in [45; 46; 47; 48]. [PERSON] et al. [45] and [PERSON] et al. [52] evaluated slicing road framework in 5G network softwarization for content delivery using Mininet-WiFi emulator. The content delivery is transmitted through V2X communication. Furthermore, [PERSON] et al. [9], [PERSON] et al. [47], and [PERSON] et al. [48] used mathematical analysis to compare the proposed scheme for content delivery. The lack of a realistic simulation tools that support OpenFlow-based edge computing coupled with vehicle traffic mobility affect the evaluation of VM migration techniques in SDVC. 4.2.3 Strategies for Virtual Machine and Service Migration in Vehicular Cloud and Edge/fog Computing  
Table 3 recapitulates some strategies for VM service migration in vehicle cloud and fog computing-based architecture for cloud-based applications. Fog computing addresses the issue of computation latency by leveraging service of VM migration assisted with migration policies.