P2P Video-On-Demand Systems Presentation

A New Retrieval Strategy A New Retrieval Strategy for P2P Video-On-Demand for P2P Video-On-Demand

SystemsSystems

Presented By… Ashwini

Ramesh More Mounika Eluri

CS 696 – Advanced Distributed SystemSan Diego State University

AGENDA

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INTRODUCTIONVoD (Video on Demand) - allows users to

select and watch/listen to video content whenever they want.

Necessity to provide instantaneous response to end-users.

Delivering the media content over the network with best response time has been a popular topic of many discussions.

Our objective is to design a retrieval strategy to achieve minimum response time and maximize the overall throughput of the system.

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DRAWBACK OF LEAST LOAD FIRST

It selects a serving peer having the least load for delivering the media content.

Since only one peer is responsible for servicing the request, it takes more time to respond to the request thereby affecting response time.

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MOTIVATIONLeast Load First strategy is time

consuming.Can we develop an algorithm which can

reduce the mean response time ?We propose an algorithm called

CollaborativeRetrieval (CoRe) algorithm which aims in minimizing the mean response time.

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CORE MODEL

10 40

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CORE MODEL

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10%

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Collaborative Retrieval

CORE ALGORITHMInput: Batch of movie requests, list of available peers, list of movie replicas

distributed across multiple peers.Output: response time for each request 1. for each request ri do 2. size = getSize(ri) 3. Get list of available peers containing the movie and store in list Lp

4. Total = count (Lp) 5. for each peer pi in list Lp do 6. Set distance with respect to the request source 7. end for 8. Sort the list Lp according to the distance factor in ascending order 9. for each peer pi in list Lp do 10. Calculate the cost, cost [pi] = distance [pi]/Total 11. Request_service_time = size * cost [pi]/transfer_rate (31Kbps

assumed) 12. end for 13. Record start time and end time for request ri 14. end for

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EXPERIMENTAL PARAMETERS

Parameter ValuesNumber of requests 2000-15000Number of peers 100Number of movies

500

Skew 50-50, 60-40, 70-30Aggregate access rate (1/s)

50, 100, 150, 200, 250, 300

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MEAN RESPONSE TIME (SKEW 70-30)

MEAN RESPONSE TIME (SKEW 60-40)

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MEAN RESPONSE TIME (SKEW 50-50)

RESPONSE IMPROVEMENT (SKEW 70-30)

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RESPONSE IMPROVEMENT (SKEW 60-40)

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RESPONSE IMPROVEMENT (SKEW 50-50)

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CONCLUSIONWe proposed an efficient CoRe strategy for

retrieving the videos. Our experimental results showed that CoRe

performs significantly better than existing Least Load First algorithm even in the case of heavy workload.

Simulations performed for skew distribution of 70-30 showed that CoRe algorithm achieved the maximum improvement of 36 percent over Least Load First. 16

FUTURE WORK Further studies in this research can be

performed by taking into consideration the issues like,

Data corruptionPeer or network failure and recovery

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Thank You !!!

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