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.
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.
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.
Point-to-Multipoint (P2MP) services in optical networks are more and more important for high-capacity applications.
Steiner tree algorithms have been investigated to compute minimum-cost multicast tree. However, it is difficult to
compute an optimal P2MP tree in multi-domain networks because of isolation of each domain. There are several
algorithms based on Path Computation Element (PCE) for computing multi-domain Point-to-point path, but computing
P2MP Traffic Engineering Label Switched Path (TE-LSP) in a multi-domain networks is still a challenge. In this paper,
three PCE-based schemes for P2MP inter-domain LSP computation are compared in full splitting capability networks,
and a novel Multi-Domain Minimum-cost Path Heuristic (MDMPH) algorithm is proposed. Simulation results proved
that the MDMPH algorithm computes P2MP tree with less cost than the other three schemes.
In this paper, we propose a colorless, directionless and contentionless (C/D/C) ROADM architecture using bandwidth
variable carriers select switches (BV-WSS) for elastic optical network and illustrate various advantages offered by it. We
also discuss some extensions for current control plane of ASON framework.
A novel restoration scheme for multi-failures based on protection ring with dynamic weight (PRDW) is proposed in this
paper. This scheme effectively resolves the multi-failures which is in one service and the conflicts by restoration between
services. PRDW use Dijkstra's algorithm to compute path and protection ring. These rings rely on protection weight
which is dynamic, so that they can as much as possible to divide multi-failures to single ones. Meanwhile PRDW
introduce independent protection weight to balance load, which effectively gets combat for resources less vicious.
Simulation results show that PRDW works better than traditional schemes.
The traditional approach for inter-domain Traffic Engineering Label Switching Path (TE-LSP) computation like BRPC
could provide a shortest inter-domain constrained TE-LSP, but under wavelength continuity constraint, it couldn't
guarantee the success of the resources reservation for the shortest path. In this paper, a Collision-aware Backward
Recursive PCE-based Computation Algorithm (CA-BRPC) in multi-domain optical networks under wavelength
continuity constraint is proposed, which is implemented based on Hierarchical PCE (H-PCE) architecture, could provide
an optimal inter-domain TE-LSP and avoid resources reservation conflict. Numeric results show that the CA-BRPC
could reduce the blocking probability of entire network.
Various broad bandwidth services have being swallowing the bandwidth resource of optical networks, such as the data
center application and cloud computation. There are still some challenges for future optical networks although the
available bandwidth is increasing with the development of transmission technologies. The relationship between upper
application layer and lower network resource layer is necessary to be researched further. In order to improve the
efficiency of network resources and capability of service provisioning, heterogeneous optical networks resource can be
abstracted as unified Application Programming Interfaces (APIs) which can be open to various upper applications
through Application-oriented Integrated Control Center (AICC) proposed in the paper. A novel Openflow-based unified
control architecture is proposed for the optimization of cross layer resources. Numeric results show good performance of
AICC through simulation experiments.
Flexible bandwidth networking has recently been proposed as a spectrally efficient networking technology that
effectively supports dynamically varying traffic demands [1]. This networking technology provides an opportunity to
maximize spectral efficiency for each of many arbitrary bandwidth channels generated using one of many possible
modulation formats [2]. Path Computation Element (PCE) is first introduced for dynamic routing and spectrum
assignment problem in elastic optical network. We proposed three centralized and distributed routing and spectrum
assignment solutions. They are Centralized Routing and Distributed Spectrum Assignment (CR+DSA), Centralized
Routing and Centralized Spectrum Assignment (CR+CSA) and Distributed Routing and Distributed Spectrum
Assignment (DR+DSA). The two centralized proposals both own PCE in its architecture. The performance of three
proposed centralized and distributed routing and spectrum assignment solutions have been analyzed and compared. For
the experimental evaluation, the performance of Centralized Routing and Centralized Spectrum Assignment is the most
adaptable RSA strategy for the whole bandwidth-variable optical networks with dynamic traffic.
The process of computing routes that network traffic must follow throughout network has become much more complex
in recent years. PCE (Path Computational Element) technology is emerging and gaining importance under the
circumstances. In this paper, PCE architecture is outlined, and the impact of PCEs allocation decisions is discussed
briefly. To track the problem of locating PCEs, an integer linear programming (ILP) model is presented to find the
optimal PCEs allocation solution in multi-domain optical networks. The objective is to minimize average amount of time
for sending a message to all nodes in the topology, i.e. message flooding cost. Then, two heuristics, LSPLP and TSPLP,
are developed based on this model. Numerical results show that compared with traditional allocation strategies, the
proposed algorithms can reduce the message flooding cost efficiently.
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