# Practical Implementation of a Blockchain-Enabled SDN for Large-Scale Infrastructure Networks
## 5 Experiments and Results  
As presented in the above section, the proposed solution was validated in a series of steps. This section aims to offer a pragmatic perspective on the validation process of the proposed solution, presenting accompanying results. It was mentioned that the last step of validation was using remote virtual machines that had available blockchain nodes, and the experiment was to confirm that they are able to connect and communicate. During this experiment, the traffic was monitored using the Wireshark tool in order to capture the communication between the nodes. The experimental duration spanned slightly under one hour, and during this period of time the ongoing traffic was captured. The nodes kept the connection and communication alive even if there was no specific information to be sent from one to another. In the course of the experiment, a total of 1173 packets were exchanged, as illustrated in Figure 4. There were multiple conversations during the exchange, shown by the multiple TCP three-way handshakes present in the capture log. The connection was established, several packets were exchanged, and then the connection was closed. The TCP three-way handshake duration was between 4.193681 and 16.477670 ms (with the SYN -> SYN ACK duration between 0.02004 and 0.11177 milliseconds, and the SYN ACK -> ACK duration between 4.147911 and 16.45667 ms). A range of 18 to 21 TCP segments (with the connection management packets included) were transmitted between nodes until the connection was closed. The connection duration was between 17.372734 and 28.115327 ms. Among the TCP traffic, UDP packets were also captured. The UDP packets were usually exchanged after the TCP connection was closed; if this was not the case, they were always exchanged after the connection was set up. The UDP streams were of different lengths and were not necessarily between two TCP connections. Figure 4: The number of packets exchanged during the entire conversation between the two nodes. Long UDP streams were interchanged between TCP streams, as presented in Figure 5. Due to the considerable variability in datagrams within the UDP streams, it is unnecessary to report the number of packets and the duration of communication. During the experiment involving the specified blockchain nodes, additional connections and interactions with other blockchain nodes were observed. The communication between the specified nodes did not exhibit any discernible impact from these concurrent connections. Thus, it is not possible to attribute the fluctuation in packet communication duration to the presence of other interconnected nodes. Analyzing the capture, it can be observed that the background interaction between the nodes was consistent in regards to the timing. The interaction was always kept alive by establishing a TCP connection, and this happened at regular times, as can be observed in Figure 7. In between the TCP connections, the UDP datagrams were sent, facilitating UDP communication. A communication delay was noted upon analyzing the recorded network traffic between the two hosts. There was a deviation in the duration of the three-way handshake time. It can be observed that, on one host, the duration between the SYN and SYN ACK packets was longer than on the other host (107.944382 milliseconds compared to 0.02314 milliseconds), and that, on the other host, the duration between the SYN ACK and ACK was longer than on the first host (105.105241 milliseconds compared to 0.061759 milliseconds). This difference can be attributed to the route the packet was sent on with the delay for SYN -> SYN ACK on one host causing a delay for SYN ACK -> ACK on the other host. Figure 5: TCP and UDP packets captured. Figure 6: The exchanged packets distribution over TCP/UDP protocols. Analyzing the captured packets, a quantitative measure can be carried out regarding the size of the packets exchanged during communication. In the case of TCP packets, the mean size was 117 bytes per packet. In the case of UDP packets, the mean size was 573 bytes per packet.