## 2 Related Works  
FlexE is an interface technology for the bearer network to realize service isolation and network slicing. Since ITU-T standard organizations have accelerated the FlexE standard process [11], it has developed rapidly in recent years. [PERSON] et al. [4] provided a solution for decoupling the interface rates between routers and transport devices from the actual data flows and evaluated the trade-off between a transport box's complexity and its ability to utilize light paths effectively, offering insights into the impact of FlexE use cases on the router port efficiency, transport box provisioning, and DWDM layer capacity in DCI contexts. [PERSON] et al. [12] explored optimized routing in complex multi-layer, multi-domain IP-optical networks using a hierarchical PCE and FlexE technology. It formulates optimization problems that consider QoS, privacy, and FlexE constraints and introduces novel algorithms for efficient routing and client assignment. [PERSON] et al. [13] addressed the security concerns in next-gen RAN transport, focusing on eavesdropping attacks at the physical layer. A cross-layer approach using FlexE and WDM is proposed for enhanced security. Various attack levels are considered, and a trade-off between resource efficiency and security is explored. The numerical results demonstrate the effectiveness of the defense strategies. [PERSON] et al. [14] addressed routing optimization in multi-layer multi-domain networks, emphasizing inter-layer and inter-domain coordination. It introduces a hierarchical path computation engine (PCE) that leverages FlexE technology to enhance the network performance by linking the IP and optical domains, presenting an efficient algorithm for routing and FlexE assignment and achieving a substantial performance improvement of an 87% optimal throughput. And, in [12], the authors investigate the FlexE Traffic Restoration (FTR) problem that aims to maintain high network utilization via the fast recovery of FlexE clients with the minimum cost using the spare capacity in the already deployed PHYs. [PERSON] et al. [15] addressed the integration of flexible Ethernet (FlexE) and elastic optical networks (EONs) in FlexE-over-EONs scenarios, specifically focusing on the FlexE-aware architecture. It introduces mixed integer linear programming (MILP) and integer linear programming (ILP) models for single-hop and multi-hop scenarios, respectively, and presents highly time-efficient approximation algorithms that provide solutions closely approaching the optimal ones in large-scale planning. Based on [12; 14], [PERSON] et al. [16] investigated the FlexE Traffic Restoration (FTR) problem that aims to maintain high network utilization via the fast recovery of FlexE clients with the minimum cost using the spare capacity in the already deployed PHYs. And, based on [13], [PERSON] et al. [17] introduced a cross-layer security design for FlexE over WDM networks, specifically addressing eavesdropping threats at the physical layer. The approach combines universal Hashing-based FlexE data block permutation with parallel fiber transmission to enhance security. The study evaluates different attack levels, balancing resource efficiency and security, and demonstrates the effectiveness of the proposed cross-layer defense strategies. [PERSON] et al. [18] investigated cross-layer restoration (CLR) in FlexE-over-EONs, specifically addressing temporary outages in FlexE switches. Extensive simulations confirm the effectiveness of these CLR strategies, highlighting the potential of FlexE and elastic optical networks for efficient restoration in scenarios involving FlexE switch outages. Recently, [PERSON], [PERSON], et al. [19] established a model of routing embedded timeslot scheduling for the routing of fine-granularity slices and timeslot scheduling problems in SPN-based FlexE interfaces, for which a deterministic timeslot allocation mechanism supporting end-to-end low-latency transmission is proposed.