Techniques for efficient routing and load balancing in content-addressable networks

As a distributed hash table (DHT), a content addressable network (CAN) provides efficient routing and object location in a decentralized manner while offering fault tolerance and dynamic peer operations. However, as opposed to other DHTs that use a flat ID space, CAN uses a multi-dimensional logical space. DHTs usually require O(logN) routing information per peer and provide routing in O(logN) hops, where N is the number of peers in the system. In CAN, on the other hand, each peer keeps only constant amount of routing information and the routing takes O(dN/sup 1/d/) hops, where d is the dimensionality of the logical space. Hence the routing performance of CAN is worse than other DHTs especially when d is small. In this paper, we describe and evaluate several schemes for efficient routing in CAN by keeping additional routing information at the peers. Furthermore, due to the underlying multidimensional ID space, CAN is used by applications that require content-based mapping of data objects onto the ID space. Since uniform hashing is not used, such mappings introduce skewed object distributions among the peers. Thus we also describe load balancing schemes for CAN and investigate their efficiency.