Disaggregated edge-enabled C+L-band filterless metro networks

Abstract

The recent interest in the upgrade and enhancements of metro transport networks and the availability of transponder cards with coherent receivers is opening the way to filterless solutions employing only passive splitters/couplers and optical amplifiers, potentially achieving significant capital expeditures and operating expenditures savings. However, the filterless option suffers from inefficiencies, mainly due to the broadcasting constraint and the reduced optical reach. To overcome such limitations, this paper proposes three complementary strategies to upgrade optical filterless metro networks (FMN). First, the number of supported channels is incremented by exploiting the full C + L -band. To this end, two design architectures (i.e., Single and Dual Region) are proposed and evaluated, targeting double capacity with respect to the standard C-band and an upgrade to cost reduction. Second, we investigate a dual-architecture solution, extending metro deployments with a low-cost filterless and unamplified L-band system. Its design trade-offs are evaluated to determine its suitability in providing direct low-latency connectivity between metro-access nodes with the aim of supporting edge-computing platforms. Finally, the flexibility of the FMN is extended by introducing disaggregated transponders with different bitrates (i.e., 100 Gbps and 400 Gbps) and configurable transmission parameters, such as the modulation format and the forward error correction). Such flexibility is exploited through the extension of the OpenConfig YANG model of the optical line system, thus enabling automatic spectrum and transmission parameter assignment by means of a centralized software-defined-network controller and achieving better resource utilization. Simulation and experimental results are provided, showing the effectiveness and the potential impact of filterless metro solutions in future deployments and low-cost network upgrades supporting edge/fog clusters and 5G.

QoT-Aware Optical Amplifier Placement in Filterless Metro Networks

“…A lighthpath i is feasible if it meets the QoT requirements, i.e., the total OSNR (which also comprises the non-linear noise from the GN-model [8]) and received power (P rec ) constraints (OSN R i > threshold and P rec,i > threshold, as defined in Eq. 5and (6) in [5]). A solution is feasible if all lightpaths meet QoT requirements (thus f = 1), whereas a solution is unfeasible if there is at least one lightpath in set I which does not meet the OSNR and/or P rec constraint (f < 1).…”

“…1. These horseshoe topologies are becoming popular in metro aggregation networks [6] and typically contain two types of nodes: Terminal nodes (T-nodes) and Filterless nodes (F-nodes). T-nodes are interconnected to the rest of the metro network and equipped with filters that impede ASE noise propagation beyond them, and thus avoid creating laser loop effects due to the continuous propagation and amplification of the optical signal [7].…”

Metropolitan Optical Networks: A Survey on New Architectures and Future Trends

“…MONs are designed with short and medium distance links, less than 200 km, usually within the limit of an optical single-span without amplification (around 80 km) [32], [44]. However, longer distances and smaller spans (multi-spans) are also possible, requiring some signal regeneration while driving the "pay as you grow" trend [1], [30]. For these networks, there are a variety of transmission systems that can be used, as well as different types of hardware elements such as building blocks, which can be organized in various ways to compose the topology of the network.…”

“…However, due to the long distances between the users and the data storage/computing infrastructure, high latency is experienced by transported traffic, so the usage experience is relevantly impacted for some applications. More recently, driven by advances in the IoT with 5G as an enabler technology, distributing data storage/processing by deploying computing and storage resources in proximity of the end users has become a major requirement for latency-sensitive services, leading to a new computation paradigm know as fog/edge computing [1], [2].…”

On Dynamic Service Chaining in Filterless Optical Metro-Aggregation Networks

“…The interest in applications of FONs in MANs has increased significantly in the recent years [16], [17]. For example, Ref.…”