Anycast in locality-aware peer-to-peer overlay networks

Abstract. This paper advocates implementing anycast in peer-to-peer (p2p) overlay networks. We argue that anycast in p2p overlays (exemplified by Pastry, Tapestry, Chord, CAN) combines the advantages of IP anycast and existing application-layer anycast services. We show that anycast can leverage the locality-awareness embedded in existing p2p overlays. The locality-awareness of the p2p routing substrates can be extended to support anycast and anycast is achieved as the result of the enhanced locality-aware routing. We have implemented anycast in Pastry, and experiments confirm that with high probability, a message addressed to an anycast group is routed to the closest node in the group according to the proximity metric. We also evaluate the performance of anycast using a realistic failure trace and the results show that our implementation of anycast is resilient to node failures.