OPNET University Program

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

I'm working on the problem of Replica Placement in Content Delivery Networks (CDNs).
I'm currently studying a heuristic that creates and deletes replicas dinamically. It has a controlled proactivity, in order to minimize user perceived delays in such a system.
Its other goal is to minimize 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 request redirection problem

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

Ph. D. Thesis, University of Rome "La Sapienza"
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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.