# A Multi-Parameter Comprehensive Optimized Algorithm for MPTCP Networks
## 4 Measurement Scenario  
We designed measurement scenarios on the distributed and programmable nodes of the NorNet Core testbed [27; 28; 29] to verify our proposed algorithm, which were spread over 23 sites on four continents. These sites were multi-homed systems and connected with multiple different ISPs over different access technologies, and most of them deployed IPv4 as well as IPv6. Figure 4 shows the sites and connectivity of the testbed.  
In order to verify the performance and reliability of our proposed algorithm, considering geographical distribution and heterogeneity of networks [27; 30], we chose six sites, and their detailed information is listed in Table 1. In this paper, we planned three measurement scenarios. In order to avoid experimental error, the average value of at least nine measurement runs was taken, over a time period of several days--including working days as well as weekends--to make sure we covered different times of the day. The effective throughput of the network was measured within a certain time (30 s). For buffer experiment, the buffer size started from 0.5 MiB, and we designed the step size with 0.5 MiB value up to the limit of 30 MiB, in total 60 sampling points for each run. The following Linux kernel setups and tools were used for the experiment:  
* Ubuntu Linux 16.04 \"Xenial Xerus\" LTS with Linux kernel version 4.19.128;
* Linux MPTCP version 0.95;
* Buffer size limit set to 30 MiB, unless otherwise specified, to prevent throughput limitations by lack of buffer space [2].  
The bandwidth measurements were performed by using the NetPerMeter (NetPerMeter: [[https://www.uni-due.de/~be0001/netperfmeter/](https://www.uni-due.de/~be0001/netperfmeter/)]([https://www.uni-due.de/~be0001/netperfmeter/](https://www.uni-due.de/~be0001/netperfmeter/)) (accessed on 10 August 2021)) [7; 31; 32] tool. It measures the application payload throughput performance of different transport connections and protocols. In particular, MPTCP was supported by NetPerMeter as well [33; 34]. Furthermore, it allowed us to configure the send and receive buffer sizes for a connection by using the SO_SNDBUF and SO_R  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  
Figure 4: The NorNet Core sites and their connectivity in the Internet.  
Note that the sites of Table 1 contain independent ISP connections, i.e., multiple paid subscriptions for Internet access. As discussed in [35], there are different perspectives of \"fairness\" for multi-path transport. In our case here, we did not assume that all subflows are guaranteed to be disjointed. However, since we paid for each ISP independently, we assumed that it was \"fair\" to use each of the sites' ISP as it would be the site's only connection to the Internet.  
Note further that while the ISP connections of Table 1 look static, there is ongoing variation in the network layer's routing, depending on different times of the day. We provide an analysis of such details in our paper [27], by analyzing HiPerConTracer measurements in detail. For this paper, we assumed the underlying network layer behavior as given (since MPTCP has no influence on the underlying routing). We covered the variation, as seen in Figure 4, by multiple runs over several days (see above).