Traffic grooming is a significant task in internetworking between an optical wavelength-routed core network that supplies "pipes" at the wavelength-granularity, and the attached client (e.g., IP) networks that usually require connections of sub-wavelength granularity. The focus of this study is to develop a theoretical performance analysis model for online traffic grooming in mesh optical networks. This paper first briefly discusses the difficulty in applying the analytic models developed for circuit-switched networks (including wavelength-routed optical networks) to the traffic grooming problem. It then develops a link blocking model based on the continuous time Markov chain and queueing theory, and finally conducts end-to-end performance analysis based on the Erlang fixed-point approximation. The results obtained from the analytic model are shown to match well with numerical results obtained from simulations.
In this paper, we have proposed an integrated lightpath traffic transport approach to groom and transport the
client traffic onto a dynamic logical topology established over the optical network. The integrated approach has been studied against the single hop and multi-hop approaches to demonstrate its benefit on improving the performance. We
have implemented heuristics for the single hop, multi-hop approaches, and three variants of the integrated approach. Three traffic patterns and two types of bandwidth distributions, totaling six traffic scenarios, have been studied with regard to the blocking probability and throughput.
In optical networks, each single lightpath can offer huge bandwidth to carry the client traffic. In many cases, the clients require the optical network to provide the survivability of the carried traffic. Hence how to route the working and protection paths to better utilize the wavelength resource is an important challenge for service providers. In this paper, we propose a joint lightpath routing approach to select the working and protection paths for the dynamic traffic. The proposed routing approach attempts to perform individual optimization on the path selection for each call request. The performance of the joint lightpath routing approach has been examined against the traditional lightpath routing approach.
No doubt, there is a need to introduce intelligence into the control plane of the optical network to provide dynamic and real-time provisioning and effective survivability. However, the traffic pattern migration from static to dynamic gives rise to many challenging issues. One such issue is the route assignment. For static traffic, the route assignment can generally be optimized using a variety of offline algorithms. For dynamic traffic, however, such a global optimization is impossible. Nevertheless, it is possible to perform individual optimization for each new call in the dynamic traffic pattern. In this paper, we propose an enhanced route assignment mechanism for the optical control plane and evaluate its performance benefits.
Recently there are considerable amount of research about the automatic control and provisioning in all optical networks. One of the critical issues is how to provide effective lightpath provisioning to improve network performance, such as blocking probability and decision time. Depending on the network topology, configuration, and administration policy, a distributed or centralized control scheme can be employed to manage the routing and signaling. In a distributed control scheme, each node exchanges information with other nodes, but performs routing and signaling independently from other nodes. On the other hand, in a centralized scheme, each node communicates with a central controller and the controller performs routing and signaling on behalf of all other nodes. Intuitively, the centralized scheme can obtain a lower blocking probability since the controller has the complete resource availability information. We have studied the two schemes through emulations, determined the signaling and processing overheads and quantified the conditions that favor one approach over the other.
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