Pastry: Scalable, distributed object location and routing for large-scale peer-to-peer systems

This paper presents the design and evaluation of Pastry, a scalable, distributed object location and routing scheme for wide-area peer-to-peer applications. Pastry performs application-level routing and object location in a potentially very large overlay network of nodes connected via the Internet. It can be used to support a wide range of peer-to-peer applications like global data storage, global data sharing, and naming. An insert operation in Pastry stores an object at a user-defined number of diverse nodes within the Pastry network. A lookup operation reliably retrieves a copy of the requested object if one exists. Moreover, a lookup is usually routed to the node nearest the client issuing the lookup (by some measure of proximity), among the nodes storing the requested object. Pastry is completely decentralized, scalable, and self-configuring; it automatically adapts to the arrival, departure and failure of nodes. Experimental results obtained with a prototype implementation on a simulated network of up to 100,000 nodes confirm Pastry’s scalability, its ability to selfconfigure and adapt to node failures, and its good network locality properties.