03/19/02Scalab Seminar Series1 Routing in Peer-to-Peer Systems Ramaswamy N.Vadivelu Scalab, ASU

03/19/02Scalab Seminar Series2 Introduction Arturo Crespo, Hector Garcia-Molina Stanford University Routing: Mechanisms for searching Non indexed Indexed Centralized Distributed Distributed indexed mechanism: “ Routing indices”

03/19/02Scalab Seminar Series3 Idea of a RI : Guide us rather than take us to a destination Nodes:A, B, C, and D Search for ‘x’ Scope of this paper: Building effective RI’s Three types of RI’s Performance evaluation of RI’s via simulations

03/19/02Scalab Seminar Series4 Some issues to be kept in mind Distributed DB vs. Peer-to-Peer approaches. Failure of nodes Number of nodes Current approaches: Gnutella Napster Freenet Objectives

03/19/02Scalab Seminar Series5 Distributed search in P2P systems User scenario: Submission of queries with a stop condition. Cycles

03/19/02Scalab Seminar Series6 Compound RI Defining Goodness. CRI Contents: No. of documents along each path No. of documents on each topic of interest Overcounts and Undercounts.

03/19/02Scalab Seminar Series7 Computing goodness: G = No. of Documents * p (CRI/ No.of Documents) Limitation:Cost difference due to hops. Comparing performance:

03/19/02Scalab Seminar Series8 Storage space. Creating RI’s: Aggregation by A Addition by D Aggregation by D Updation Maintaining RI’s. Disconnection: Key point.

03/19/02Scalab Seminar Series9 Observations: Efficiency Disconnection process Expensive operations Trade off Limitation

03/19/02Scalab Seminar Series10 Hop count RI Store aggregated RI’s for each hop. Upto a maximum number of hops - Horizon. Need for a cost model.

03/19/02Scalab Seminar Series11 Number of messages Regular tree model No.of documents per message >Goodness Creation by shifting. Updation. Drawback Higher transmission and storage Lack of performance beyond a horizon

03/19/02Scalab Seminar Series12 Exponentially aggregated RI’s Stores the result of tree cost formula at each node. Same assumptions of a regular tree cost model. Difference: Information beyond the Horizon. Updation “different enough” condition

03/19/02Scalab Seminar Series13 Cycles Cycles resulting in infinite loops. Solutions No –op solution Avoidance Detection and Recovery

03/19/02Scalab Seminar Series14 No–Op technique: Hop count and Exponential RI Avoidance: Absence of global information may result in sub-optimal networks. Detection and Recovery: Detects after they have been formed Steps to neutralize the effect of cycles May affect the accuracy of the RI.

03/19/02Scalab Seminar Series15 Observations and Conclusions Efficiency of Content Search. Introduced the concept of RI’s. Types of RI’s. Mechanisms of these RI’s. Discussions ?