Web Caching and Content Distribution:
A View From the Interior

Overview

Generalized Cache/CDN (External View)

Generalized Cache/CDN (Internal View)

Goals and Limitations

Outline

Analytical Model

Cacheable Hit Ratio: the Formula

Inside the Hit Ratio Formula

An Idealized Hierarchy

Hit Ratio at Interior Level i

Root Hit Ratio

Generalizing to CDNs

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Hit ratio in CDN caches

Analysis

Analysis (cont’d)

Cacheable interior hit ratio
observed at interior level
fixing interior/leaf population ratio

Interior hit ratio
as percentage of all cacheable requests, fixing interior/leaf population ratio

Cacheable interior hit ratio
as percentage of all requests
fixing leaf population

Cacheable interior hit ratio
as percentage of all requests
varying Zipf a parameter

Cacheable interior hit ratio
as percentage of all requests
 varying Zipf a parameter

Conclusions (I)

Correlating with NLANR Observations

Model vs. Reality

Cacheable interior hit ratio
varying percentage of requests detected as uncacheable by leaves

Cacheable interior hit ratio
varying percentage of requests detected as uncacheable at request time

Conclusions (II)

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Modeling CDNs

Hit ratio with detected uncacheable documents