# Resilience Evaluation of Multi-Path Routing against Network Attacks and Failures
## 4 Evaluation
### Comparison between SP, FMP and MMP Routing  
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 5, the path \(p_{0}=\{Src\to A\to B\to D\to F\
earrow Dst\}\) between \(Src\) and \(Dst\) shows under heavy traffic of the communication.  
* \(p_{0}=\{Src\to A\to B\to D\to F\
earrow Dst\}\): A low-latency path that will be under heavy traffic of communication.  
Figure 4: Global topology using SCIONLab for a real-world network evaluation. The core ASes are placed at Carnegie Mellon University (CMU) in the United States (US), Magdeburg in Germany, SWISSCOM (SCMN) in Switzerland, NUS in Singapore, and KISTI Daejeon in Korea. The links between the core ASes are operated as a transit-link for communication. All links are adopted as multi-path to show the effectiveness of MMP. The ETHZ node includes two ASes.  
* \(p(SP)=\{Src\to A\to B\to D\to E\to F\
earrow Dst\}\): A high-latency path that will initially be used as a single path.
* \(p(FMP)=\{Src\to A\to C\to D\to F\searrow Dst\}\): A low-latency path that will be partially affected by an attack.
* \(p(MMP)=\{Src\to A\to C\to D\to E\to F\searrow Dst\}\): A high-latency path that will mostly be unaffected by an attack.  
As aforementioned, FMP cannot deal with network congestion or a link failure if the problem occurs in other hops that FMP cannot control. However, because MMP can take advantage of a path that an FMP, such as SD-WAN, cannot control, MMP can mitigate the problem if such a situation occurs. Figure 5 shows the topology uses for an evaluation towards comparison between FMP and MMP under such a situation. We assume that AS \(A\), which controls the source, uses SD-WAN, and, because an SD-WAN configuration through cooperation with other ASes is difficult, we also assume that the SD-WAN does not control the path passing other AS hops. We use \(p(SP)\), \(p(FMP)\), and \(p(MMP)\) as the path of SP, FMP, and MMP routing.  
If traffic congestion occurs in path \(\{A\to B\to D\}\), path \(\{D\to F\}\), and path \(\{F\
earrow Dst\}\), then both links configured for SP and FMP will suffer a degradation in network performance even though SD-WAN switches its link from a SP path \(p(SP)\) to an FMP path \(p(FMP)\), or vice versa. However, when it comes to \(p(MMP)\), it can be used as an alternative option because MMP can control the path outside the source AS. Because path \(\{A\to C\to D\}\), path \(\{D\to E\to F\}\), and path \(\{F\searrow Dst\}\) are unaffected by traffic congestion, using this \(p(MMP)\), we can mitigate the network performance degradation.  
Figure 6 and Table 1 show the results of the network performance of each path \(p(x)\) when \(x\) is SP, FMP or MMP, under traffic congestion. If traffic congestion occurs on the \(p(x)\) mentioned previously, \(p(SP)\) and \(p(FMP)\), which are options for SD-WAN, will suffer from degraded network performance with an average increase in latency of approximately 46% (SP: 270 ms to 396 ms) and 31% (FMP: 318 ms to 419 ms), and a loss rate of 4.7% and 4%, respectively. However, for the \(p(MMP)\), which is an alternative path that can be configured using MMP, the network suffers from almost no network performance degradation.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Path** & **Loss Rate** & **Avg. Latency** \\ \hline \(p(SP)\) & 4.7\% & 396.66 ms \\ \(p(FMP)\) & 4\% & 419.19 ms \\ \(p(MMP)\) & 0\% & 318.73 ms \\ \hline \hline \end{tabular}
\end{table}
Table 1: Average latency and loss rate with _FMP paths_ and _MMP path_ during attack.  
Figure 5: Topology used for comparison between MMP and FMP. The solid bold line indicates heavy traffic. The scenario is a case in which the traffic congestion affects both paths of FMP and MMP, whereas the alternative path found by MMP does not.