Progress in network technologies and protocols is paving the road towards flexible optical transport networks, in which dynamic leasable circuits could be set up and released on a short-term basis according to customers requirements. Recently, new solutions for automated network management promise to allow customers to dinamically specify the terms of the Service Level Agreement (SLA) to be guaranteed by the service provider. Since this new information is made available, we propose to exploit the knowledge of connection holding time, among the other Service Level Specifications (SLS), to improve the routing efficiency. In this work, we consider that a typical electronic-layer (e.g., SDH or MPLS) demand requires only a fraction of the capacity of the single wavelength bandwidth and we investigate a new algorithm for traffic grooming of sub-wavelength connections in an optical mesh network. We rely on the knowledge of the holding time of connection requests to exploit lightpath capacity and hence to achieve significant reduction in blocking probability for the traffic grooming problem. Our new methodology is applied on a typical US nation-wide network and results are compared with those given by previous known approaches.

Cost is a major concern in telecom industry. Cost-efficient network design has been attracting the attention of network operators (NO). Wavelength-division multiplexing (WDM) optical technology is being widely deployed in telecom networks for their high capacity. Backbone telecom networks, which are mesh-connected, employ optical crossconnects (OXC) at switching nodes; and OXC deployments today are of the opaque (optical-electronic-optical, OEO) variety. In such a network, the number of OXC ports is a major portion of the cost of the switching equipment (not counting the cost of the transmission equipment, which is needed anyway independent of the switching equipment). In this work, we focus on a practical situation in which a bundle of ports are fabricated on a single blade, called a line card (LC). If we are restricted to using only bundles of ports per LC, this will impose an extra constraint on cost-efficient network design, especially for asymmetric traffic between node pairs and arbitrary network topologies. Our design relies on a two-step approach using two algorithms whose objective is to reduce the number of LCs (ports). First, we route traffic connections on low-cost paths where cost depends on how much resources are needed to support the connection. The second step is a reassignment step, which tries to re-optimize the outcome of the first step. Simulation was conducted on a sample backbone network. Results show a reduction in cost (in terms of the number of deployed LCs) by nearly 6%.

Reconfigurable OADMs (ROADMs) provide flexibility and enables fast provisioning of dynamic traffic in ring-based metro optical WDM networks. We investigate the online connection provisioning and propose heuristics to combat various constraints in this network.

We investigate the design of a WDM backbone network with optical cross-connects (OXCs) of different switching granularities to reduce the network-wide OXC port cost. We enhance our proposed graph model (Zhu, H. et al., IEEE/ACM Trans. Networking, vol.11, p.285-99, 2003), and the extended graph model can represent different node architectures in which a node may have multiple OXCs with different switching granularities simultaneously. Based on this model, we propose a provisioning algorithm for a single connection and a framework for network design, which can intelligently determine the type of OXCs at each node according to the traffic so that the benefit of different types of OXCs can be utilized. Numerical examples are presented showing that granularity-heterogeneous networks are more cost-effective than granularity-homogeneous networks.

As the operation of our fiber-optic backbone networks migrates from interconnected SONET rings to arbitrary mesh topology, traffic grooming on wavelength-division multiplexing (WDM) mesh networks becomes an extremely important research problem. To address this problem, we propose a new generic graph model for traffic grooming in heterogeneous WDM mesh networks. The novelty of our model is that, by only manipulating the edges of the auxiliary graph created by our model and the weights of these edges, our model can achieve various objectives using different grooming policies, while taking into account various constraints such as transceivers, wavelengths, wavelength-conversion capabilities, and grooming capabilities. Based on the auxiliary graph, we develop an integrated traffic-grooming algorithm (IGABAG) and an integrated grooming procedure (INGPROC) which jointly solve several traffic-grooming subproblems by simply applying the shortest-path computation method. Different grooming policies can be represented by different weight-assignment functions, and the performance of these grooming policies are compared under both nonblocking scenario and blocking scenario. The IGABAG can be applied to both static and dynamic traffic grooming. In static grooming, the traffic-selection scheme is key to achieving good network performance. We propose several traffic-selection schemes based on this model and we evaluate their performance for different network topologies.

We employ a new, generic graph model for dynamic traffic grooming in WDM mesh networks. The novelty of this model is that, by only manipulating the edges of an auxiliary graph created by the model and the weights of these edges, the model can achieve various objectives using different grooming policies, while taking into account various constraints. Based on the auxiliary graph, we develop a dynamic traffic-grooming algorithm. Different grooming policies can be implemented by different weight functions assigned to the edges in the auxiliary graph. We propose four fixed grooming policies and an adaptive grooming policy (AGP), and our results show that AGP outperforms the fixed grooming policies.