## 4 Experimental Results  
### Description of the Simulation Stand  
In order to obtain initial data about the implementation of the CAs, an integrated computer simulation model of a data transmission network using SDN was developed (Figure 9). This model covers a network connecting the main office (Main Office) with four subordinate offices (from Office 1 to Office 4). Routers (from rtk 1001 to rtk 1007) provide VPN services to the base stations (from base station 1 to base station 4) that provide communication channels between offices. SDN technology network devices are designated as OvS. The place through which a computer attack is made is base station 4 (marked as AttackEnemy).  
The model was developed in order to study the resilience of SDN in the conditions of CAs, taking into account the features of its functioning (information exchange, network equipment settings, the use of monitoring tools, etc.). The peculiarity of this model is its complexity. Firstly, using SDN technology in a virtual environment, images of real network devices of telecom operators, as well as images of Open Flow devices of switches and the Runos 2 controller, were used. Secondly, to simulate the load, instead of packet generator programs, the programs designed for information exchange with real equipment were used. Thirdly, several software products were used to collect and analyze traffic in parallel, which makes it possible to assess the reliability of the obtained network statistics. Finally, during the planning and conducting of the CA stages, the average time for their implementation was taken into account, which was calculated during the performance of a given number of experiments.  
Figure 9: Computer simulation model of a data transmission network using SDN.  
The model was developed on the basis of the EVE-NG virtual network laboratory. Unlike the well-known Mininet virtual network environment simulation program [63], the EVE-NG system allows you to create models using real hardware and software to simulate the real functioning of SDN. For this reason, images of real equipment devices used in corporate data transmission networks were added to the model: Dionis-NX, Juniper, Cisco, Huawei and others. Linux images (Ubuntu) with installed software routers OpenvSwitch were used for SDN modeling, and the Runos 2.0 controller model was used as the controller image.  
Table 8 lists the software products, device images and real equipment used in the simulation computer model of the data transmission network applying SDN technology.  
To collect and process network statistics, Nfsen2 (Netflow Sensor) [64] and Wireshark [65] software products, as well as the Zabbix [66] network monitoring tool, were installed on a separate computer.  
External devices are connected to the virtual model of the data transmission network. External devices are virtual or real traffic generation devices. The model uses workstations on Linux Ubuntu operating systems, with the help of which videoconferencing is organized, as well as the image of the Proteus-SP [67] automatic telephone exchange, which simulates the exchange of information between users via IP telephony and messaging using mail server.