## 7 Results
In the single-attack scenarios, the QoS performance degraded and the network became less stable while experiencing high increases in control traffic overhead and power consumption. Table 4 shows that single attacks caused a reduction of up to 13% in the PDR and throughput in S1 and up to 20% in S2 and S3. In addition, high increases in delay and ETX of up to 74% were experienced considering all three experimental setups. Network stability was also significantly affected as shown in Figure 4a. It can be seen in all the setups that the PPC rate increased by 3-8 changes/node on average. It was also very challenging for the RPL network to maintain high beacon intervals during the different routing attacks as shown in Figure 5a. In S1, the rates of DIO and DAO transmissions increased by more than 25 packets per minute as shown in Figures 6a and 7a. Scaling the network up in S2 and S3 made the situation even worse as more than 100 and 180 control packets were transmitted per minute, respectively. Another increase was also experienced as the consumed energy increased by more than 150% in all three experimental setups as indicated in Figure 8a. When the performed RPL routing attacks became composite, more performance degradation and stability difficulty were experienced. Compared to the single-attack results, Table 5 shows that the QoS measures were adversely affected by the composite attacks with up to 9% additional degradation. Figure 5b indicates a reduction of more than 20% in beacon interval. Control traffic transmission was increased by more than 17% as shown in Figures 6b and 7b. Moreover, the results presented in Figures 4b and 8b indicate high increases in the PPC rate by more than 12 changes/node on average and in the total consumed energy by more than 400 joules, respectively. The overall performance and stability of standard RPL networks became even worse during hybrid RPL routing attacks. This was more apparent for the network overhead as can be noticed in Figures 6c and 7c. That is, additional control traffic transmission of more than 40% was experienced during hybrid attacks compared with composite attacks. Another noticeable divergence can be seen when comparing the PPC rates in Figure 4c. Clearly, the hybrid attacks resulted in more unstable network topologies than the composite attacks. There were more than 4 changes/node on average during the hybrid attacks considering all the experimental setups. Figure 8c shows that energy consumption also increased by more than 10%. The results presented in Table 6 indicate that the overall QoS performance degraded by up to 7% considering all three experimental setups. It can be seen from the overall results that hybrid routing attacks are generally more effective in targeting standard RPL networks than other routing attack strategies. Another important aspect is understanding the most adverse routing attack for standard RPL networks. Considering the single-attack scenarios, Table 4 shows that the VN attack is the most effective routing attack when compared with the other attacks. Similar observations can be made when examining the results of the composite-attack scenarios in Table 5. Single and composite VN attacks resulted in additional QoS degradation by 2-9% compared to the other attacks. The results presented in Figure 4a,b, Figure 5a,b, Figure 6a,b, Figure 7a,b and Figure 8a,b also indicate the same outcome. Single and composite VN attacks caused additional energy consumption by more than 17%. Higher DIO and DAO  
Figure 8: Energy Consumption Results: (**a**) Single-Attack Scenario; (**b**) Composite-Attack Scenario; (**c**) Hybrid-Attack Scenario. transmissions of more than 19 control packets per minute and higher PPC rates of up to 7 changes/node on average were also experienced during the single and composite VN attacks. These observations became more evident as the network scaled up. The next in the order of effectiveness for single- and composite-attack scenarios was the rank attack.