Kademlia: P2P Distributed Hash Table with Petar Maymounkov

Napster, Kazaa, and Bittorrent are peer-to-peer file sharing systems. In these P2P systems, nodes need to find each other. Users need to be able to search for files that exist across the system. P2P systems are decentralized, so these routing problems must be solved without a centralized service in the middle.

Without a centralized service that has all the information in one place, how can you solve these problems of node discovery and file lookup? This is the central question that Petar Maymounkov sought to answer with Kademlia.

Kademlia is a peer-to-peer distributed hash table. Kademlia implements the “put” and “get” operations of an efficiently scalable hash table without using any centralized service. Each node in the system maintains its own routing table. When a user queries the system (a “get” operation), that query is serviced by the nodes coordinating with each other to intelligently route the user to their target location. When a file is stored (a “put” operation), that update to the file system can propagate through the network in a decentralized, uncoordinated way.

Petar joins the show to give a brief history of P2P networks, why he created Kademlia, and what he is working on today.

Transcript

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