CLON: overlay network for clouds

Gossip-based protocols have been gaining an increasing interest from the research community due to the high resilience to node churn and high scalability, thus making them suitable to modern large-scale dynamic systems. Unfortunately, these properties come at the cost of redundant message transmissions to ensure bimodal delivery to all interested peers. In systems with high message throughput, those additional messages could pose a significant burden on the excess of required bandwidth. Furthermore, the overlays upon which message dissemination takes place are oblivious to the underlying network, or rely on posterior optimizations that bias the overlay to mimic the network topology. This contributes even more to the required bandwidth as 'undesirable' paths are chosen with equal probability among desired ones. In a Cloud Computing scenario, nodes tend to be aggregated in sub-nets inside a data-center or in multiple datacenters, which are connected by costlier, long-distance links. The goal of this work is, therefore, to build an overlay that approximates the structure of the physical network, while ensuring the connectivity properties desirable to ensure reliable dissemination. By having each node judiciously choose which nodes are in its dissemination list at construction time, i.e. by giving preference to local nodes, we are able to significantly reduce the number of messages traversing the long-distance links. In a later stage, this overlay shall be presented as a service upon which data dissemination and management protocols could be run.