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University: Rome "La Sapienza"
Name of sponsoring Professor: prof. Chiara Petrioli
Department: Computer Science

Research:

The tool has been used to study and simulate the behavior of content delivery networks, in particular to study the problem of dynamic replica placement and traffic load balancing. We're currently studying a replica placement heuristic that creates and deletes replicas dinamically. It has a controlled proactivity, in order to minimize user perceived delays in such a system.
 As a secondary goal, the heuristic minimizes the CDN provider costs, by minimizing the number of variations in the system and the number of allocated replicas.
 We addressed the replica placement problem jointly with the problem of balancing the traffic in CDNs request redirection systems, thus obtaining a solution that allows to trade-off among the number of replicas, the user-perceived service performance, the number of replica additions and removals.

Papers:

Title: Distributed Dynamic Replica Placement and Request Redirection in Content Delivery Networks

, IEEE MASCOTS 2007, October 2007

Abstract

The Content Delivery Networks (CDN) paradigm is based on the idea to transparently move third-party content closer to the users. More specifically, content is replicated on CDN servers which are located close to the final users, and user requests are redirected to the ``best'' replica (e.g., the closest) in a transparent way, so that users perceive a better content access service. In this paper we address user requests redirection and replica placement in CDNs. Differently from previous solutions our scheme considers the two problems jointly and relies on distributed and localized schemes that can be implemented with little complexity and overhead, thus providing a new overall solution that effectively trades-off among the number of replicas, their utilization (i.e., how many users requests they serve), the distance from the best replica and the number of replica adds and removals. An OPNET based thorough performance evaluation has allowed us to assess the effectiveness of the proposed solution. By properly tuning the distributed heuristics parameters the CDN provider can have a strict control on the CDN network operations so that the desired trade-off between all the relevant performance metrics is achieved.

Teaching:

  • "Advanced Topics in Computer Networks" - during the course, we will held seminars on OPNET and its applications in solving problems related to wireless networks and advanced network design
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