Optical networks serve an increasing number of services, each having different requirements. This necessitates the evolution towards routing algorithms that cover all aspects of quality. This article presents a tutorial overview and comparison of grade-of-service-based routing strategies, with emphasis on mechanisms that provide differentiated call-blocking probability for different classes of lightpath requests

Advantages of Software Defined Networking are unquestionable and are widely described in numerous scientific papers, business white papers and press articles. However, to achieve full maturity, crucial impediments to this concept and its shortcomings must be overcame. One of the most important issues regards significant setup latency of a new flow. To address this issue we propose PARD: a hybrid proactive and reactive method to manage flow table entries. Additional advantages of the proposed solution are, among the others, its ability to preserve all capabilities of Software Defined Networking, utilization of multiple flow tables, a possibility to employ fine-grained traffic engineering and, finally, compatibility with existing protocol and hardware design. It is shown that the proposed solution is able to significantly reduce latency of first packets of a new flow, which directly impacts packet loss and perceived throughput. Thus, our solution is expected to enable a wide deployment of Software Defined Networking concept without any need for protocol changes or, what is extremely important, hardware modifications.

The paper focuses on cooperation between cloud and network operators, as well as on fitting particular routing strategies to various cloud services. Three cooperation models are presented, analyzed and compared in the paper: the proposed model and two widely used reference models. The main difference between the models is the set of information being exchanged between the involved parties. Additionally, we analyze the applicability of four fitting schemas for each considered model. It is shown that the proposed model, alongside with an appropriate fitting schema, is able to reduce the blocking probability of cloud services requests. At the same time, thanks to the use of green anycast strategies, it is able to significantly reduce carbon dioxide emission.

In the paper we propose three route management strategies that allow an optical network operator to achieve differentiated service for two classes of lightpath requests. Simulation results show that all three strategies achieve the stated goal, which is to maintain blocking probability of high priority requests below an assumed value in a broad range of network loads. Moreover, the presented strategies require only little support from the control plane. Detailed algorithms are presented in two versions, one suitable for networks with centralized control, and the other for networks with distributed control.

As the cloud computing paradigm evolves, new types of cloud-based services have become available, including security services. Some of the most important and most commonly adopted security services are firewall services. These cannot be easily deployed in a cloud, however, because of a lack of mechanisms preserving firewall policy confidentiality. Even if they were provided, the customer traffic flowing through the Cloud Service Provider infrastructure would still be exposed to eavesdropping and information gaining by performing analysis. To bypass these issues, the following article introduces a novel framework, known as the Ladon Hybrid Cloud, for preserving cloud-based firewall policy confidentiality. It is shown that in this framework, a high level of privacy is provided thanks to leveraging an anonymized firewall approach and a hybrid cloud model. A number of optimization techniques, which help to further improve the Ladon Hybrid Cloud privacy level, are also introduced. Finally, analysis performed on the framework shows that it is possible to find a trade-off between the Ladon Hybrid Cloud privacy level, its congestion probability, and efficiency. This argument has been demonstrated through the results of conducted experiments.

The paper is focused on an optical network in which the network operator needs to achieve differentiated connection blocking probability between different classes of lightpath requests. We propose and investigate several routing strategies, which may be used for that purpose, i.e., to maintain the blocking probability of the high priority requests below an assumed value in a broad range of network loads. Simulation results show that all proposed strategies achieve the stated goal, but their performance varies considerably. The paper presents differences in performance of individual strategies.