## 2 Related Works  
Related studies are presented in this section on routing algorithms for LEO satellite networks. These algorithms find routing paths in a distributed manner, reducing communication overhead that occurs during the topology update process that changes due to unexpected link failure. We sequentially introduce studies on finding the optimal detour route without updating the routing topology. Distributed routing configures the topology without global link-state information. Each satellite has an independent routing table. Information exchange between satellites to construct the topology is reduced. A datagram routing algorithm (DRA) was proposed in [12]. In DRA, each satellite independently selected the next hop, with the destination determined based on the logical addresses of the satellites. In [13], the authors proposed the semi-distributed routing algorithm (SDRA). SDRA calculates up to the next hop of the next hop and records this information in the packet header. In [14], the authors proposed local-assisted on-demand routing (LAOR), which is commonly used in mobile ad-hoc networks. LAOR defines the minimum hop region (MHR) from the source to the destination of the satellite. LAOR only finds the routing path when transmission requests it. In [15], the authors proposed a disruption-resistant on-demand routing protocol (DODR) for local repair. DODR improved with the ad-hoc on-demand distance vector routing algorithm. DODR allows routes that change according to frequent topology changes to be detoured through local repair. In [7], the authors proposed on-demand dynamic routing. Regular topological changes are managed through static routing by employing memory-efficient static routing, enabling each satellite to update its routing table without information exchange independently. In the sudden topological changes due to link instability, only the changed link-state information is propagated through the network using on-demand dynamic routing. The distributed routing algorithm does not involve additional information exchange with neighboring satellites, making it ineffective for addressing unexpected link failures. However, sharing information about faulty links for topology reconfiguration can lead to substantial communication overhead. Studies have been presented to reduce the number of messages shared on networks. In [16], the authors proposed a topology pruning algorithm to reduce overhead during flooding. The orbits of each satellite in the LEO network topology are connected inter-plane. This is a technique for pruning the topology by selecting the shortest inter-plane ISL connecting orbits and connecting each orbit to one inter-plane. In [17], the authors proposed an algorithm that minimized the use of inter-plane links to the destination. To select a routing path, the optimal satellite is chosen that can move into the orbit of the next satellite within the network topology. In [18], the authors proposed a minimum-hop binary tree pruning traversal-based earliest arrival (MHBTEA) routing algorithm. MHBTEA generates the routing path as a binary tree and searches for new paths by pruning the tree according to topology changes. Studies are presented to minimize the number of shared link status messages by clustering satellites. In [19], the authors proposed area-based satellite routing. The network topology is divided into inter- and intra-areas. Each area independently manages its routing table in a distributed manner, and changes in links occurring within an intra-area are propagated only within the same area. In [20], the authors proposed a satellite clustering algorithm. Utilizing game theory, an optimization problem has been formulated to address cluster reliability and management overhead. A hierarchical network architecture has also been proposed, wherein topology changes are managed by other satellites, taking into account the onboard constraints of LEO satellites.