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This paper proposes a new approach to designing alternate routing algorithms for all-optical wavelength-division multiplexing networks in order to reduce the connection blocking probability. The key idea is to try to route traffic in approximately the optimal way of splitting the traffic among the multiple routing paths between each source-destination pair. The optimal way of splitting the traffic among the multiple routing paths between each source-destination pair is obtained by solving a nonlinear multicommodity flow optimization problem. Two alternate routing algorithms, namely, traffic intensity based fixed-alternate routing algorithm and traffic intensity based dynamic-alternate routing algorithm, are proposed based on this approach. Simulations are performed to study the performances of the proposed alternate routing algorithms. Our simulation results show that the alternate routing algorithms designed according to the optimal way of splitting the traffic can effectively reduce the connection blocking probability.

The emergence of peer-to-peer (P2P) applications has posed a threat to the operating cost of Internet Service Providers (ISPs) due to the large amount of inter-ISP traffic generated. The problem stems from the mismatch between the P2P overlay network formed randomly and the underlying physical network. Recently, BitTorrent has attracted enormous users by its convenience of large-scale content distribution and has also become a major challenge for ISPs. Therefore, in this paper we proposed an effective B-Proxy scheme to evaluate through realistic simulation on PlanetLab, where hundreds of BitTorrent clients were executed during the experiment. Simulation results show that more than thirty percent of inter-ISP traffic could be saved in a torrent with a relatively small cache size consumed which is only eighth times that of the original file.

This paper proposes a new fixed-alternate routing algorithm for all-optical WDM networks without wavelength conversion in order to reduce the connection blocking probability. The key idea in the proposed fixed-alternate routing algorithm is to try to route the traffics in approximately the optimal way. The multiple routing paths between each source-destination pair are arranged and used in descending order according to the traffic intensities obtained by solving a nonlinear multicommodity flow optimization problem. It is well known that finding the connection blocking probability is a very difficult task. Therefore, an objective function closely related to the connection probability is devised and used to formulate a nonlinear multicommodity flow optimization problem. Simulations are performed to study the performance of the proposed fixed-alternate routing algorithm. Our simulation results show that sorting the routing paths according to the optimally assigned traffic intensities in the proposed fixed-alternate routing algorithm can effectively reduce the connection blocking probability compared with sorting the routing paths according to hop counts in a typical fixed-alternate routing algorithm. In general, in all-optical WDM networks, a connection request that goes through a longer path experiences higher connection blocking probability than a connection request that goes through a shorter path. This is known as the fairness problem. Our simulation results show that the proposed algorithm yields better fairness than a typical fixed-alternate routing algorithm.