NODE LOOK UP IN PEER-TO-PEER NETWORK
NODE LOOK UP IN PEER-TO-PEER NETWORK P2P: Large connection of computers, without central control where typically each node has some information of interest. No central control for routing No central data repository Has several legitimate uses !! So two basic questions: How to make data at each node available ? How to find required information ? Both question are of course interrelated, but we will look at them seperately. ASSUMPTION We assume that each record (data to be shared) can be identified by a ASCII string such as the filename. Over the past 3-4 years there has been several proposals for P2P architectures, we will look at Chord. Uses a hash function such as SHA-1. SHA-1 converts a variable length input into a highly random 160 bit value BASIC OF CHORD Using SHA-1 Chord hashes, node IP addresses node identifiers (160 bits) names of records keys (160 bits) STORING RECORD Conceptually the 2^160 nodes are arranged into a circle increasing clockwise. For example, for 2^5 nodes wo