## 2 Related Work  
### Proactive Approaches  
When link failures occur in the network, the most vital point is whether they can be recovered promptly; therefore, the speed of failure recovery is the primary consideration, as it directly affects the efficiency of network operation. Many studies have been carried out around this point, making the proactive approach naturally the most suitable. [PERSON] and [PERSON] [20] built a system that allows switches to send erroneous link information only to relevant switches to prevent traffic flooding and enhance the performance of centralized networks. Thus, when a link failure occurs in the network, the corresponding switch will create a link failure message (LFM) and send it to the relevant switches. Their experiment shows that switches are notified of link failures earlier compared with when the controller recognizes and commits updates. Likewise, the research of [PERSON] [21] et al. supports the implementation of fault detection monitoring functions in the data plane without involving the controller. For this, they generate monitoring messages inside the source switch and process these messages in another target switch. If the target switch cannot receive these packets for an extended period, their method concludes that the current path is faulty. Their experiment shows that this function can achieve data plane fault recovery within 50 ms in a scalable way. In the study by [PERSON] [22] et al., they expanded previous research [23] and developed a proactive fault recovery scheme by carrying backup path information in the packet header. Thus, when a link failure occurs, their system uses backup path information to maintain communication without consulting the controller. In the packet header, they use VLAN and MAC Ethernet fields to pass the backup path information. [PERSON] [24] et al. proposed a new language based on regular expressions to implement fault-tolerant network programs in SDN using OpenFlow fast fault transfer groups. They allow developers to specify the set of paths that packets may traverse through the network and the desired degree of fault tolerance. Therefore, their compiler generates rule tables and group tables to provide the specified fault tolerance capability. Correspondingly, [PERSON] [25] et al. proposed a rule-based language pattern framework to achieve fault tolerance. In addition, [PERSON] [26] et al. use finite state machines for rapid fault detection and recovery in the data plane. [PERSON] [27] et al. present a hybrid failure restoration approach for SDN. Utilizing Bayesian probability for congestion prediction, this approach proactively determines backup paths while dynamically managing post-recovery congestion. This method effectively reduces packet loss and RTT, improving overall network throughput. Its integration of proactive path computation with reactive congestion management offers a nuanced solution to SDN failure restoration. Following the introduction of OpenFlow protocol version 1.1, research started using fast failover group tables, as they offer numerous advantages in terms of fault tolerance,including recovery time and path traffic control. For this, [PERSON] [28] et al. considered operator-grade networks, where failure recovery should be completed within 50 ms. Therefore, they executed the protection mechanism using OpenFlow fast failover group tables. Experimental results showed that the protection mechanism reduced the time needed for failure recovery and alleviated traffic load on the controller. Additionally, in another study by [PERSON] [29] et al., they focused on failure recovery for in-band OpenFlow networks, where control and data traffic are transmitted over the same channel, and they applied the same scenario. In the study by [PERSON] [30] et al., they implemented traditional graph algorithms, including BFS, DFS, and Module, to compute backup paths. These backup paths were used for FF groups. [PERSON] [11] et al.