The distributed spanning tree: a scalable interconnection topology for efficient and equitable traversal

Peer-to-peer and grid applications currently have few structures that allow efficient discovery mechanisms in large scale system. The trees can be an appropriate structure for this task. However, the tree's bottlenecks are a significant drawback in large scale architectures and connected graphs are used most of the time. In this paper, we propose an appropriate architecture named distributed spanning tree (DST) to allow discovery in large scale environment. This structure is organized into a hierarchy of groups. The nodes are put together in groups and groups are gathered in groups of higher level, recursively. This organization, built on top of routing tables allows the instantaneous creation of spanning trees rooted by any nodes and keeps the load balanced between the nodes. The first studies about the distributed spanning tree suggest that it has all the advantages of a tree without its drawbacks. This can be explained by the following complexity order: each node stores only O(log(n)) information; a parallel traversal needs n - 1 messages and takes O(log(n)) units of time; adding or removing a node needs O(n) messages in the worst case but only needs in average O(log(n)) messages. Load balancing and fault tolerance are ensured by the architecture of the distributed spanning tree itself.