Analysis of TTL-based Cache Networks

Abstract : 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.
Document type :
[Research Report] RR-7883, 2012
Contributor : Philippe Nain <>
Submitted on : Tuesday, March 6, 2012 - 11:00:57 AM
Last modification on : Wednesday, January 23, 2013 - 10:04:58 AM




  • HAL Id : hal-00676735, version 1



Nicaise Choungmo Fofack, Philippe Nain, Giovanni Neglia, Don Towsley. Analysis of TTL-based Cache Networks. [Research Report] RR-7883, 2012. <hal-00676735>




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