# Resilience Evaluation of Multi-Path Routing against Network Attacks and Failures
## 4 Evaluation
### Single Path and Concurrent Multi-Path  
An evaluation of utilization of multiple available MMP paths is also applied to compare the performance using two and four paths, which are written as a multi-path above. In Figure 7, the node _Src_ uses the path \(p_{0}=\{Src\to A\to B\to D\to F\
earrow Dst\}\) for communication as an SP routing. For two paths, we used \(p_{0}\) and \(p_{3}\), and, for four paths, we used \(p_{0}\) to \(p_{3}\) as explained below:  
* \(p_{0}=[Src\to A\to B\to D\to F\
earrow Dst]\): A low-latency path that will initially be used by _Src_ as a single path. An attacker will directly attack this path during communication. * \(p_{1}=[Src\to A\to C\to D\to F\searrow Dst]\): A low-latency path that will be partially affected by an attack. * \(p_{2}=[Src\to A\to C\to D\to E\to F\
earrow Dst]\): A high-latency path that will be partially affected by an attack. * \(p_{3}=[Src\to A\to C\to D\to E\to F\searrow Dst]\): A high-latency path that will mostly be unaffected by an attack. Figure 8 and Table 2 show the results of the comparison when using two paths and four paths for MMP. The paths are selected uniformly at random for the case of '2 paths (random)' and '4 paths (random)'. We sent SCMP packets for 1 s each during a 10 s period (for a total of 10 packets), which consumed the bandwidth for 3 s (from seconds 4 to 7). Because the network status changes owing to the bandwidth consumption of an attacker, selecting stable paths will ensure a much more stable communication with high  
Figure 6: Latency comparison of FMP and MMP when traffic congestion occurs during 4–7 s. Both paths of SP and FMP are affected, whereas the alternative path that MMP found is unaffected. Figure 7: Topology used for MMP evaluation. Dotted curved line shows the user’s communication path and the bold dotted line shows the attacker’s attack path. availability than selecting paths at the same ratio. Here, '4 paths (weighted)' represents selecting 4-times more stable paths than the paths being attacked, and '4 paths (random)' corresponds to randomly selecting all four paths. The loss rate and average latency of a single path are greater than those obtained using 'MMP: 2 paths (random)' and 'MMP: 4 paths (random)'. Moreover, when using 'MMP: 4 paths (random)', the performance is less affected by an attack with only an approximate 10% increase in the average latency than when using 'MMP: 2 paths (random)' during a bandwidth consumption attack (4-7 s), which shows an increased average latency of approximately 20%. In addition, although the latency showed an improvement, the loss rate shows almost no change because other paths (\(p_{1}\) and \(p_{2}\)) used for 'MMP: 4 paths (random)' evaluation already encountered a loss rate even when no attack takes place. As observed in Figure 8, 'MMP: 4 paths (weighted)' using four times more stable paths mitigate the effect of an attack (during seconds 4 to 7) compared with 'MMP: 4 paths (random)' at the same ratio, because a _weighted_ path selection shows an average increased latency of approximately only 4% and a loss rate of 0.5%, whereas a random path selection shows an increased average latency and loss rate of 10% and 2.5%, respectively. However, there is a limitation on _weighted_ multi-path, that is, we assume that the attacker is a passive attacker, and that the user knows which path is being attacked. As a future study, we would like to conduct research on utilizing an optimized path selection algorithm by using the network status of each path and the AS information on the paths to deal with an active attacker who recognizes that the user has changed paths. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Path** & **Loss Rate** & **Avg. Latency** \\ \hline SP: 1 path & 7.5\% & 422.22 ms \\ MMP: 2 paths (random) & 3\% & 362.77 ms \\ MMP: 4 paths (random) & 3\% & 330.09 ms \\ MMP: 4 paths (weighted) & 0.5\% & 313.07 ms \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Experimental results of an SP and MMP for the measurement of loss rates and latency during the attack.