We propose to compare the hardware cost of OTN switching and IP switching to obtain the ballpark adaptation range for the two switching mode. By abstracting the switching behavior of OTN switching equipment and IP router, we present a detailed study on the hardware cost in the case of ensuring connectivity. A unified network-level connection model is established based on CLOS switching network, and then we compare hardware costs for IP switching and OTN switching. The hardware cost of the two switching mode in different L1 switching granularity and different port rate cases is simulated. Simulation results show that OTN switching has lower hardware cost than IP switching when average bandwidth for traffic demand excess 250Mbps in the cases of ODU0 switching granularity.
The performance monitoring of fiber-optics communication is an important task in nowadays communication system. Link optical noise-to-signal ratio (OSNR) is one of the most important parameters that affect the performance of optical networks. The traditional internal measurement method may increase the network construction cost and operation complexity. To overcome these drawbacks, an ANN based link OSNR estimation method with external measurement is proposed in this paper. Route level OSNR values are measured at the edge nodes and are used for link level OSNR estimation with the trained ANN. Besides, a heuristic method for route set generation is proposed to generate the route set that introduce fewer extra network load. The experiment results demonstrate that the ANN based method can meet the practical requirement in both estimation accuracy and computation complexity. The proposed method can be an important part of optical network OSNR monitoring to ensure robust and intelligent network operation.
Flexible optical networks (FONs) are used to handle the enormous bandwidth demands and significantly improve the flexibility and efficiency of spectrum resources. This flexibility opens the door to strategies that can optimize the allocation of spectrum resources. The dynamic setup and teardown of traffic will inevitably fragment these resources and increase the network blocking probability. Different modulation formats can be configured to guarantee efficient spectrum resource allocation by taking the transmission distance into account. We investigated routing and fragmentation-avoiding spectrum allocation for the unicast service over FONs with the constraints of spectrum resource and transmission distance. To alleviate spectrum fragmentation, the available spectrum adjacency (ASA) is used to estimate the adjacency among available spectrum block resources on routing paths or links. A distance-adaptive fragmentation-avoiding spectrum resource allocation (DA-FASA) algorithm based on ASA and genetic operators is proposed to resolve the spectrum fragmentation problem in FONs. The DA-FASA algorithm defines an ASA value for the free spectrum blocks on each routing path and each modulation format to maximize spectrum availability, which effectively reduces the spectrum fragmentation and network congestion. Simulation results indicate that DA-FASA exhibits highly efficient performance with regard to the bandwidth blocking probability and the spectrum utilization ratio under different network scenarios, compared to the benchmark algorithms.