Building a network-aware and load-balanced peer-to-peer system for range queries

We present a structured P2P system called Donuts for range queries, which takes two important yet somewhat conflicting issues into account: proximity and load balance. Proximity allows physically close nodes to be arranged near each other in the overlay so as to reduce the cost of neighbor communications that occur quite often in a range-queriable system. Load balance is crucial because object distribution in a semantically meaningful key space is often skewed. Efficient load balance, however, requires flexible node position in the overlay, and thus conflicts with proximity.Donuts resolves the problem by separating physically close nodes into several overlay sections. By dynamically switching between these sections, they help one another balance their loads without altering overlay proximity too much. Still, breaking apart physically close nodes inevitably compromises overlay proximity. Therefore, we have put much effort in the overlay construction to ensure that load balance can be performed effectively and efficiently, with minimal damage to overlay proximity.