# A Performance Evaluation for Software Defined Networks with P4
## 6 Results and Analysis of Tier 2--Multiple Types of Traffic Running Simultaneously
### Case Study 5--Mixed Type of Traffic over Grid Topology  
Five types of traffic from Table 1, ICMP, VoIP, TCP, UDP and CDN, were run simultaneously. The performance of each type of traffic is presented in Table 5. Table 5 (ICMP traffic) reports an improvement of 6.7% in throughput for _SDN+P4_ in comparison to the throughput achieved by _SDN+OvS_. Table 5 (TCP traffic) records an improvement of 12% in throughput from 1.05 \(\times\) 10\({}^{7}\) bps for _SDN+OvS_ to 1.18 \(\times\) 10\({}^{7}\) bps for _SDN+P4_. These are represented in Figure 9(a),b by the blue line. Packet loss, packet delay, synchronisation delay and total transmission time achieved significant reductions for _SDN+P4_ over _SDN+OvS_ of 36%, 6%, 77% and 18% respectively.  
Table 5 (UDP traffic) reports an increase in UDP throughput of 43% (from 7 \(\times\) 10\({}^{6}\) bps for _SDN+OvS_ to 1.0 \(\times\) 10\({}^{7}\) bps for _SDN+P4_) as illustrated in Figure 9(a),b by the red line. It was also observed that _SDN+P4_ completed the download of 1 GB of UDP traffic in 800 s in contrast to _SDN+OvS_ which took 1020 s. Packet loss, delay, and jitter were each observed to have reduced values for _SDN+P4_ in comparison to those obtained using _SDN+OvS_, these being 73%, 78% and 48% respectively. The reduction in jitter for UDP packets is shown in Figure 9(c).  
Table 5 (CDN traffic) records an increase of 5% in throughput from 3.8 \(\times\) 10\({}^{5}\) bps for _SDN+OvS_ to 4 \(\times\) 10\({}^{5}\) bps for _SDN+P4_. This is illustrated by the green line in Figure 9(a),b. Higher throughput resulted in _SDN+P4_ transferring more data (817.54 MB) in comparison to _SDN+OvS_ (588.41 MB), an improvement of 38% for the same video file. Buffer delay and jitter in _SDN+P4_ resulted in significant reductions of 38% and 5% respectively, in contrast to _SDN+OvS_. The reduction in jitter is shown in Figure 9(d).  
The difference in throughput has an effect on the quality of the video. Figure 9(a) shows a comparison for the 34 th frame captured during the experiments for both _SDN+OvS_ and _SDN+P4_. The same frame was sent from the server side, with the client side in _SDN+OvS_ displaying a distorted frame in comparison to that received by the client with _SDN+P4_.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**Internet Topology-Single Type of Traffic**} \\  & \multicolumn{3}{c}{**(CDN)**} \\ \cline{2-4}  & **SDN+OvS** & **SDN+P4** & **Improvement** \\ \hline Throughput & 1.0 \(\times\) 10\({}^{6}\) bps & 1.6 \(\times\) 10\({}^{6}\) bps & 60\% \\ \hline Data transmitted & 1609.17 MB & 2308.88 MB & 43\% \\ \hline Buffering delay & 12.94 s & 2.17 s & (\(-\)83\%) \\ \hline Jitter & 0.342 ms & 0.261 ms & (\(-\)41\%) \\ \hline \hline \end{tabular}
\end{table}
Table 4: _Cont._Figure 11: Comparison of CDN frames for both _SDN+OvS_ and _SDN+P4_ for case studies 5 and 6. (**a**) Grid topology at 90s (**b**) Internet topology at 90s.  
Figure 10: Data for mixed traffic over the simple-grid topology—case study 5. (**a**) Throughput for mixed traffic for _SDN+OvS_. (**b**) Throughput for mixed traffic for _SDN+P4_. (**c**) Jitter in UDP Transmission for mixed traffic. (**d**) Jitter in CDN Transmission for mixed traffic.