# A Reliable Routing Algorithm Based on Path Satisfaction in the Energy Internet
## 4 Solution Approach
### Path Satisfaction-Based Service-Aware Routing Algorithm (PSSRA) for the Energy Internet
Moreover, due to the aggregation feature of services (that is, services always generate from the lower voltage substations and terminate at higher voltage substations or control centers in the EI) and other constraints, such as both end-to-end latency and SRLG severely affect the link availability, the number of available paths sharply decreases when service requests increase. Accordingly, the service distribution discrepancy is not obvious in the network as the service increases. Moreover, we find that JFI values with the PSSRA are larger than the other two approaches. This shows the effectiveness of the proposed path satisfaction-based routing strategy. We compared the SBRs for services with different levels under the PSSRA approach in the 14-node network, which is shown in Figure 3:0 It is noted that the SBRs show similar trends in different networks. Therefore, the transmission of level 1 services is guaranteed. Furthermore, the SBRs of level 2 services gradually increase, and the remaining two levels

Figure 3:1 JFI variation under different approaches in the 7-node network. The oblique line denotes the result of our approach, the rhomboid form is the results of SPA, and the green denotes the result of the SCRA. Figure 3:2 The SBR with the PSSRA at different levels in the 7-node network. rapidly grow. The average SBRs of three levels, i.e., levels 2, 3, and 4, are 0.51%, 2.66%, and 3.60%, respectively. The reason for this has also been shown in Figure 3:3 Moreover, we found that the SBRs increase with the increasing service requests in both small and large networks. A large number of service requests and a long duration time may lead to fewer feasible routing paths and consequently lead to high SBRs. Figure 10 shows the JFI variation with the number of service requests for different algorithms carried out on the 14-node NSF network topology. The same trend is shown in Figure 3:4 We found that JFI values decrease with the increasing service requests. This indicates that a small number of services show a balanced distribution in the network due to a greater choice of feasible paths at the beginning. With the increase in services, there are fewer appropriate routing paths in the network, and consequently, services tend to aggregate on some links. Therefore, the metric of the JFI is lower with the increase in services in the network. Figure 11 demonstrates the computational time of the PSSRA and other heuristic algorithms. We found that the computational time of the PSSRA is extremely approximate to other comparison approaches, which are based on a greedy strategy. We found it

Figure 3:5 JFI variation under the different approaches in the 14-node network. Figure 3:6 The SBR of the PSSRA with different service levels in the 14-node network. It can be found that services with higher levels have lower SBRs, and vice versa. increases with the increasing service requests, and this indicates the effectiveness of the PSSRA. The variation of SBR with PSSRA in different network topologies is shown in Figure 3:7 It is noted that SBRs of service requests are decreasing with the increase in network scale. The main reason for this is that there are more path choices in comparison with a small-scale network. Consequently, there are more available spectrum resources on possible routing paths to guarantee a better transmission performance with services. However, the routing path is comparatively fixed in the small scale of network, and there are fewer available paths for services. Therefore, services have higher SBRs in the 7-node network compared with the 28-node network. Meanwhile, there are higher SBRs with an increase in services in the same network due to the increasing requirement for spectrum resources.