Authors: Jason Min Wang, Brahim Bensaou
Publisher: GLOBECOM 2012
Presenter: Chai-Yi Chu
Date: 2013/05/08
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Introduction
Proposed Caching Management Scheme
◦ Caching Decision Policy
◦ Replacement Strategies
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Simulation
◦ Experimental Methodology
◦ Experiment Results
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propose a new caching scheme for such CCN networks
and evaluate the in-network caching performance of
this policy by comparing it with that of the default
proposed policy via simulation.
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Characteristics that have crucial influence on the
caching performance
1. Locality of references
2. Content popularity distribution
3. One-time referencing
4. Heavily-tailed object size distribution
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Caching Decision Policy
◦ Resemblance to the LCD algorithm (Leave Copy Down)
◦ Choosing the immediate downstream node of the cache hit
point as the primary candidate place to replicate the data
packet.
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◦ 𝑑𝑝 : the number of interfaces saved in the PIT entry, that is,
from how many distinct interfaces requests for the same
namedchunk 𝑝 are aggregated.
◦ 𝑟𝑝 : the actual number of individual requests for p at an edge
node.
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Replacement Strategies
◦ Edge nodes
 A modification of the Greedy Dual-size algorithm.
 Each cached chunk of data 𝑝 is associated with a value 𝐻𝑝 .
 𝐶𝑝 : the hop count needed to fetch the packet.
 An “inflation” value 𝐿 = min 𝐻𝑞 .
𝑞
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◦ Intermediate nodes
 Each cached chunk of data 𝑝 is associated with a value 𝐻𝑝 .
 Interface 𝑓.
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 Diversity information will be recorded in 𝑆𝑝 and 𝑆𝑝 is used
to leave breadcrumbs on the access statistics of 𝑝 after it has
been cached.
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Implemented a simplified CCN model on top of
Omnet++
◦ simulation model includes three basic components of CCN
i.e., CS, PIT and FIB
◦ other features of CCN (e.g., hierarchical naming, routing,
security issues and so on) are not taken into account.
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Experimental Methodology
◦ Network topology
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◦ Workloads
 The synthetic Web workload generator ProWGen is used to
generate workloads for the two content servers.
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◦ Performance metric
 systematic hit gain 𝐺 =
ℎ∈𝐻 𝑔ℎ
∗ 𝑛ℎ /
𝑖∈𝐶,𝑗∈𝑁𝑖 𝑠𝑗
∗ 𝑝𝑖𝑜𝑗
 𝑔ℎ : the distance between node 𝑖 and the original content server.
 𝑛ℎ : the amount of pending requests at edge nodes for the hitting
data.
 𝑠𝑗 : the size of object 𝑗 (chunks).
 𝑝𝑖𝑜𝑗 : the hop distance between node 𝑖 and the original content
server 𝑜𝑗 of object 𝑗.
 The closer the value of G is to 1, the better the in-network
caching system performs.
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◦ Methodology
 cache size
 varied uniformly from 100 to 8,000 chunks for all nodes.
 The chunk size is set 10KB
 request aggregation
 request aggregation time can change the observed access pattern
and thus impact the hit rates of the nodes.
 cache management scheme
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alwayscache+LRU (the initial proposal of CCN
proposed PCP+heterogeneous replacement algorithms
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Impacts of cache size and content popularity
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Impact of request aggregation
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