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This paper explores the joint impact of two capacity enhancement schemes in optical backbone networks: multi-band expansion from C+L to C+L+S bands and varying 3R regeneration (no, selective, and full). Using a pay-as-you-grow batch upgrade framework that considers deferral benefits, we evaluate their interaction. In the short-haul BT-UK network, S-band upgrade consistently improves throughput and cost efficiency, with the greatest economic gain with no regeneration. In the long-haul USNET network, S-band upgrade reduces throughput because K-least-loaded routing does not consider path distance, yielding low-quality lightpaths with high blocking probability. Thus, C+L bands with full regeneration are more cost-effective. 

We present our latest development and experimental validation of carrier cooperative recovery for enhancing the resilience of optical packet transport networks. Experimental results prove that in case of resource crunch caused by, e.g., traffic congestion, failures, man-made/natural disasters, etc., swift and low-cost recovery can be achieved by exploiting the interconnection capability among carriers, which demonstrates a novel use case of multi-carrier interconnection technology. 

We propose a rapid restoration strategy against PNE-node failure during postdisaster cooperation among DC providers and optical-network carriers. Our strategy reduces disruption and improves DC-service restoration by 35% in 20% less time compared to baseline. 

Cooperation among telecom carriers and datacenter (DC) providers (DCPs) is essential to ensure resiliency of network-cloud ecosystems. To enable efficient cooperative recovery in case of resource crunch, e.g., due to traffic congestion or network failures, we previously studied several frameworks for cooperative recovery among different stakeholders (e.g., telecom carriers and DCPs). Now, we introduce a novel Multi-entity Cooperation Platform (MCP) for implementing cooperative recovery planning, to achieve efficient use of carriers’ valuable optical-network resources during recovery. We adopt a Distributed Ledger Technology (DLT) that ensures decentralized and tamper-proof information exchange among stakeholders to achieve open and fair cooperation. To support diverse types of cooperation, we develop a state machine representing the MCP operation and define state transitions associated to stakeholders’ cooperation within the state machine. Moreover, we propose a signaling system in MCP to ensure simple and reliable state transitions for stakeholders during the cooperative recovery planning in large ecosystems. We experimentally demonstrate a proof-of-concept DLT-based MCP on a testbed. We showcase a DCP-carrier cooperative planning process, showing the flexibility of the proposed MCP to support diverse types of cooperation. 

Large-scale network-cloud ecosystems are fundamental infrastructures to support future 5G/6G services, and their resilience is a primary societal concern for the years to come. Differently from a single-entity ecosystem (in which one entity owns the whole infrastructure), in multi-entity ecosystems (in which the networks and datacenters are owned by different entities) cooperation among such different entities is crucial to achieve resilience against large-scale failures. Such cooperation is challenging since diffident entities may not disclose confidential information, e.g., detailed resource availability. To enhance the resilience of multi-entity ecosystems, carriers are important as all the entities rely on carriers’ communication services. Thus, in this study we investigate how to perform carrier cooperative recovery in case of large-scale failures/disasters. We propose a two-stage cooperative recovery planning by incorporating a coordinated scheduling for swift recovery. Through preliminary numerical evaluation, we confirm the potential benefit of carrier cooperation in terms of both recovery time and recovery cost/burden reduction. 

We investigate the problem of future disaster-resilient optical network-cloud ecosystems. We introduce our solutions considering openness/disaggregation and cooperation for single- and multi-entity network-cloud ecosystems, respectively. 

The high reliability required by many future-generation network services can be enforced by proper resource assignments by means of logical partitions, i.e., network slices, applied in optical metro-aggregation networks. Different strategies can be applied to deploy the virtual network functions (VNFs) composing the slices over physical nodes, while providing different levels of resource isolation (among slices) and protection against failures, based on several available techniques. Considering that, in optical metro-aggregation networks, protection can be ensured at different layers, and the slice protection with traffic grooming calls for evolved multilayer protection approaches. In this paper, we investigate the problem of reliable slicing with protection at the lightpath layer for different levels of slice isolation and different VNF deployment strategies. We model the problem through an integer linear program (ILP), and we devise a heuristic for joint optimization of VNF placement and ligthpath selection. The heuristic maps nodes and links over the physical network in a coordinated manner and provides an effective placement of radio access network functions and the routing and wavelength assignment for the optical layer. The effectiveness of the proposed heuristic is validated by comparison with the optimal solution provided by the ILP. Our illustrative numerical results compare the impact of different levels of isolation, showing that higher levels of network and VNF isolation are characterized by higher costs in terms of optical and computation resources.