Master Thesis - 2008

In recent years, the Internet trac has been growing so fast due to its rapid development. Although the current IP routing, based on the shortest path algorithm, has shown its scalability in the Internet, the shortest path is not always the optimal path.

Overlay network, which is a logical network constructed over an underlying IP network, is a promising approach to overcome this problem. Overlay routing is a routing method based on overlay networking in which end-to-end route selection can often find better alternative paths by relaying trac among overlay nodes. When several overlay networks are constructed over the same underlying IP network, overlay paths on dierent overlay networks may share some links on the IP network. In general, however, since overlay networks do not realize the existence of other ones, they have no consideration on such shared physical links. Shared physical links, therefore, cannot be used eectively, which may lead to a decline in overlay routing performance.

To overcome this problem, the cooperative routing method for multiple overlay networks has been proposed. The method improves the throughput of all overlay networks by estimating the change of the achievable bandwidth of each overlay trac sharing the some physical links. However, to improve the eciency of shared physical links, it should take not only the achievable bandwidth of overlay trac but also the residual holding time of it into account. In this thesis, I propose a enhanced cooperative routing method considering residual holding time for multiple overlay networks. It selects the route that minimizes the sum of the transfer time of new trac and the increases on residual holding time of other tracs.

Moreover, the verification about feasibility to measure the impact among overlay networks has not been enough. I evaluate the availability of the proposed method by simulation experiments and confirm the feasibility by implementation.