The document proposes a cooperative in-network caching approach for time-shifted TV in content-centric networks. It presents a distributed algorithm that assigns "labels" to cache routers to maximize the in-network cache hit ratio. Simulations of the augmented CCN protocol show it caches 60% more unique content chunks across the network and reduces overall cross-domain traffic by 60% compared to a basic LRU caching approach. Future work is needed to deploy the system on real networks and use actual time-shifting viewing data.

1. Time-Shifted TV in
Content Centric
Networks
the Case for Cooperative
In-Network Caching
Zhe LI and Gwendal SIMON

2. Context
Routers with cache (or Content Routers or CR)
an opportunity to revisit content delivery
a key element of content centric network
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3. Context
Routers with cache (or Content Routers or CR)
an opportunity to revisit content delivery
a key element of content centric network
Motivations for ISP :
minimize incoming video traffic
enter the Content Delivery Network game
reduce overall traffic on intra-ISP links
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4. Our Focus : Time-shifted TV
Principles :
a show broadcasted at t is available at any t + x
let’s surf the TV channel
the killer app of connected TV
3 / 11 Z. Li and G. Simon Time-shifted TV in content-centric networks

5. Our Focus : Time-shifted TV
Principles :
a show broadcasted at t is available at any t + x
let’s surf the TV channel
the killer app of connected TV
A nightmare for TV broadcasters
clients skip ads
the cost of servers that both ingest and deliver
a service that is (yet) not well mastered by CDN
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6. Objective : maximize in-network hit-ratio
Inputs (or hypothesis) :
TV channel : a series of chunks (e.g. 1 min video)
each CR reserves storage for time-shifted service
CCN implemented !
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7. Objective : maximize in-network hit-ratio
Inputs (or hypothesis) :
TV channel : a series of chunks (e.g. 1 min video)
each CR reserves storage for time-shifted service
CCN implemented !
Constraints on in-network caching policies
distributed and based on local information
deployed (but not managed) by network operators
dealing with many small storage capacities
not affecting the simplicity of CCN routing
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8. Our idea
Least Recently Used (LRU) → collaborative LRU
every CR manages one chunk every k chunks
cooperation among linked CRs
CCN with LRU CCN with collaborative cache
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9. Our contributions
A distributed algorithm : assigning “labels” to CRs
a NP-complete problem
a 3 k − 2 approximate algorithm
2
5
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10. Our contributions
A distributed algorithm : assigning “labels” to CRs
a NP-complete problem
a 3 k − 2 approximate algorithm
2
5
A set of simulations from an augmented CCN
the description of the new CCN protocol
the evaluation of performances
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11. Initialization phase : assign labels to CR
sorted list nearest neighbors
2 1,4,5
3 1,8,16
1 2,3,16
6 8 3,11,12
7 5 1,2,4
11 8,12,13
10 4 2,5,7
16 1,3,5
13 4 12 8,9,11
15 2
15 1,10,11
5 10 2,6,15
1 18 14 3,16,17
11
17 5,14,16
8 3 13 11,12,15
16 7 2,4,6
12
6 2,7,10
9 8,12,14
17 18 4,5,17
14
9
7 / 11 Z. Li and G. Simon Time-shifted TV in content-centric networks

12. Initialization phase : assign labels to CR
sorted list nearest neighbors
2 1,4,5
3 1,8,16
1 2,3,16
6 8 3,11,12
7 5 1,2,4
11 8,12,13
10 optimized 4
16
2,5,7
1,3,5
13 4 12 8,9,11
15 2
15 1,10,11
5 10 2,6,15
1 18 14 3,16,17
11
17 5,14,16
8 3 13 11,12,15
16 7 2,4,6
12
6 2,7,10
9 8,12,14
17 18 4,5,17
14
9
7 / 11 Z. Li and G. Simon Time-shifted TV in content-centric networks

13. Initialization phase : assign labels to CR
sorted list nearest neighbors
2 1,4,5
3 1,8,16
1 2,3,16
6 8 3,11,12
7 5 1,2,4
11 8,12,13
10 4 2,5,7
16 1,3,5
13 4 12 8,9,11
15 2
15 1,10,11
5 10 2,6,15
1 18 14 3,16,17
11
8 3
optimized 17
13
5,14,16
11,12,15
16 7 2,4,6
12
6 2,7,10
9 8,12,14
17 18 4,5,17
14
9
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14. Initialization phase : assign labels to CR
sorted list nearest neighbors
2 1,4,5
conflict 3 1,8,16
1 2,3,16
6 8 3,11,12
7 5 1,2,4
11 8,12,13
10 4 2,5,7
16 1,3,5
13 4 12 8,9,11
15 2
15 1,10,11
5 10 2,6,15
1 18 14 3,16,17
11
17 5,14,16
8 3 13 11,12,15
16 7 2,4,6
12
6 2,7,10
9 8,12,14
17 18 4,5,17
14
9
saved but colored
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15. Initialization phase : assign labels to CR
sorted list nearest neighbors
2 1,4,5
conflict 3 1,8,16
1 2,3,16
6 8 3,11,12
7 5 1,2,4
11 8,12,13
10 4 2,5,7
16 1,3,5
13 4 12 8,9,11
15 2
15 1,10,11
5 10 2,6,15
1 18 14 3,16,17
11
17 5,14,16
8 3 13 11,12,15
16 7 2,4,6
12
6 2,7,10
9 8,12,14
17 18 4,5,17
14
9
saved and uncolored
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16. Initialization phase : assign labels to CR
sorted list nearest neighbors
2 1,4,5
3 1,8,16
1 2,3,16
6 8 3,11,12
7 5 1,2,4
11 8,12,13
10 4 2,5,7
16 1,3,5
13 4 12 8,9,11
15 2
15 1,10,11
5 10 2,6,15
1 18 14 3,16,17
11
17 5,14,16
8 3 13 11,12,15
16 7 2,4,6
12
6 2,7,10
9 8,12,14
17 18 4,5,17
14
9
colored by node 10
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17. Initialization phase : assign labels to CR
sorted list nearest neighbors
2 1,4,5
3 1,8,16
1 2,3,16
6 8 3,11,12
7 5 1,2,4
11 8,12,13
10 4 2,5,7
16 1,3,5
13 4 12 8,9,11
15 2
15 1,10,11
5 10 2,6,15
1 18 14 3,16,17
11
17 5,14,16
8 3 13 11,12,15
16 7 2,4,6
12
6 2,7,10
9 8,12,14
17 18 4,5,17
14
9
only node uncolored
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18. Initialization phase : assign labels to CR
sorted list nearest neighbors
2 1,4,5
3 1,8,16
1 2,3,16
6 8 3,11,12
7 5 1,2,4
11 8,12,13
10 4 2,5,7
16 1,3,5
13 4 12 8,9,11
15 2
15 1,10,11
5 10 2,6,15
1 18 14 3,16,17
11
17 5,14,16
8 3 13 11,12,15
16 7 2,4,6
12
6 2,7,10
9 8,12,14
17 18 4,5,17
14
9
choose farthest color
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19. Simulation environment
ISP network configuration :
rocketfuel E-bone topology with 87 CR
5 servers located near Point of Presence routers
130 chunks in every CR
augmented CCN protocol
Time-shifted TV streaming :
200 clients and 6 channels
usage extracted from Nielsen measurements 1
1. Three Screen Report Q1, Nielsen Company, June 2010.
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20. Diversity of chunks into the whole network
With k = 6, the system caches 60% more different chunks than basic LRU.
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21. ISP Friendliness
The overall cross-domain traffic is reduced by 60%.
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22. Future Works
Improve the evaluation
deploy the augmented CCN on network platforms
use real traces of time-shifters
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23. Future Works
Improve the evaluation
deploy the augmented CCN on network platforms
use real traces of time-shifters
Toward new in-network caching policies
theoretical framework for policy analysis
play with CR : behavior and capacity
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