## 3 Development of Software-Based Router and Traffic Generator
### Performance Analysis of The Software-Based Router Using the Designed Network Traffic Generator  
In order to deploy the test network and obtain adequate simulation results, the developed software components (the router and generator) must first be tested. The maximum performance of these models is tested in accordance with RFC 2544 recommendation [52]. This recommendation was developed by the Network Working Group, created within the framework of the open international community of designers, scientists, network operators and Internet Engineering Task Force (IETF) providers. On the basis of this document, specialists from the Ethernet/IP working group (ODVA) developed a detailed description of testing procedures for network devices operating on the first and second layers of the TCP/IP model, and a somewhat extended set of tests. In the case where the study is conducted not on a model, but on a real network, it is necessary to use software that will act as a generator and receiver of traffic to test performance. Such software can simulate the behavior of an individual user as well as a group of users. In the latter case, as the number of users increases, the traffic characteristics deteriorate, as the program processes only one user at a time and the operating system protocol stack delays the transmission of packets. These factors will affect the time parameters of packet transmission, degrade the quality and accuracy of the obtained results of the study of the quality of service parameters of multiservice flows in general. This method can be used to investigate traditional IP networks, as the  
Figure 2: Software-based router model with modular structure. destination host address and service type are important when routing packets. It is this information that is used by routing protocols when routing and most methods of optimizing the process of data transmission and load balancing in the network. The main advantage of this method is the ability to generate large amounts of traffic of different classes (the maximum flow rate depends on the maximum speed of the network card of the server on which the generator is installed). A traffic generator has been designed to test the developed software router. UML-diagram of the developed packet generator is shown in Figure 3.  
With this generator it is possible to create a data stream with different packet sizes. These packets can be transmitted both by UDP protocol and TCP. Using the Wireshark program, the characteristics of real VoIP, video on demand, IPTV and internet data service streams (packets size and their transmission intensity per second) are determined and researched. Using the developed generator it is possible to reproduce any type of service. It is also possible to generate different flows simultaneously, which will allow to generate multiservice traffic (Figure 4). Figure 3: UML diagram of the traffic generator. To get adequate results with the software router models it is necessary to check the quality of the traffic generator. This check is to determine the measurement error of the inter-packet interval when generating packets. The smaller the standard deviation of the inter-packet interval values, the smaller the error and greater adequacy of the simulation results. Investigation of the generator quality is carried out using a series of tests. Each series differs in the size of the inter-packet interval and the size of the package itself. Figure 5 shows a graph of inter-packet interval values for 100,000 packets. The inter-packet interval is 10 ms, the size of the packet is 1500 bytes. As a result of modelling, the following statistical characteristics of a number of values of the inter-packet interval were obtained: mean value \(-1.00845\times 10^{7}\) ns; variance \(-1.73237\times 10^{12}\) ns\({}^{2}\); standard deviation \(-1.3162\times 10^{6}\) ns; average error \(-4163.33\) ns.