hal-00676735, version 1

## Analysis of TTL-based Cache Networks

Nicaise Choungmo Fofack (, ) a1, Philippe Nain (, ) a1, Giovanni Neglia (, ) b1, Don Towsley (, ) c2

N° RR-7883 (2012)

Résumé : This paper provides building blocks for the performance evaluation of Content Centric-like Networks (CCNs). In CCNs if a cache receives a request for a content it does not store ({\em miss}), it forwards the request to a higher-level cache, if any, or to the server. When located, the document is routed on the reverse-path and a copy is placed in each cache along the path. In this paper we consider a cache replacement policy based on Time-to-Lives (TTLs) like in a DNS network. A local TTL is set when the content is first stored at the cache and is renewed every time the cache can satisfy a request for this content (at each hit). The content is removed when the TTL expires. Under the assumption that requests follow a renewal process and the TTLs are exponential random variables, we determine exact formulas for the performance metrics of interest (average cache occupancy, hit and miss probabilities/rates) for some specific architectures (a linear network and a tree network with one root node and $N$ leaf nodes). For more general topologies and general TTL distributions, we propose an approximate solution. Numerical results show the approximations to be accurate, with relative errors smaller than $10^{-3}$ and $10^{-2}$ respectively for exponentially distributed and constant TTLs.

• Domaine : Informatique/Réseaux et télécommunications
• Mots-clés : Cache architecture – content-centric network – timer – Markov model – renewal theory
• Référence interne : RR-7883
• Commentaire : Voir aussi actes de la conférence : ValueTools - 6th International Conference on Performance Evaluation Methodologies and Tools - 2012 (2012) (http://hal.inria.fr/hal-00760915)

• hal-00676735, version 1
• oai:hal.inria.fr:hal-00676735
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• Soumis le : Mardi 6 Mars 2012, 11:00:57
• Dernière modification le : Mercredi 23 Janvier 2013, 10:04:58