Xstream

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Xstream A large-scale P2P video on-demand
streaming media protocol
Amiad Stern, Barak Schlosser, Danny Bickson,
Elan Pavlov, Danny Dolev
Web site http//www.huji.ac.il/labs/danss/Xstr
eam
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The Problem

• Given a video file, we would like to enable a
• large number of users to concurrently watch
• the movie over the Internet.
• Users may leave and enter the system at
• any stage
• The servers workload should be kept as low
• as possible
• Users can join in any viewing offset

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Our Solution

• Users are gathered into flexible groups, where
• each group represent a time frame on the
• stream offset
• Users download packets from users located
• ahead of them on the stream

Server
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Our Solution

• Packets are buffered in a sliding window manner
• User can be part of more than one group
• - helping other users in the system

Server
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Our innovations

• Reduce servers workload
• - servers workload does not depend on the
• number of users in the system

• Load balancing of the system
• - preventing bottlenecks by utilizing users
• spare bandwidth

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Our innovations

• Locality awareness
• - peers selection will be random as
• long as the users buffer is full
• - in case of real time constraint expires
• selects close peers
• (based on Julia algorithm)
• - when buffer is full again -
• back to random peers selection

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Planned work

• Complete implementation in c

• Tests on PlanetLab planetary test bed and
• Evergrow cluster test bed

• Compete existing protocols results
• - servers workload
• - overall communication work
• - continuity index
• ( of frames that arrive before
• real time constraint expires)

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