Delay-Aware Push/Pull Protocols for Live Video Streaming in P2P Systems Alessandro Russo, Renato Lo...
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Transcript of Delay-Aware Push/Pull Protocols for Live Video Streaming in P2P Systems Alessandro Russo, Renato Lo...
Delay-Aware Push/Pull Protocols for Live Video Streaming in P2P Systems
Alessandro Russo, Renato Lo CignoDISI – University of Trento, Italy
locigno @ disi.unitn.ithttp://disi.unitn.it/locigno
http://napa-wine.eu
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 2
P2P Multimedia Streaming
P2P is cool, but why streaming? And why live, real-time streaming Think of out-of-country TV broadcasting
easier to get Internet connection than a satellite dish Think of the cost of starting a new TV channel
traditional TV broadcasting vs. client-server vs. P2P
P2P-TV could become one of the dominant multimedia applications on the Internet Some systems already deployed: PPLive, TVAnts,
CoolStreaming, … with hundreds of channels already available
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 3
P2P Multimedia Streaming contd.
P2P-TV is resource-hungry previously unseen traffic volumes to/from the users
1+ mbit/s sustained download Even higher upload (if available)
P2P-TV is challenging to design large peer count with heterogeneous networking resources
This is not VoD, potentially millions of users watching the same live channel
tight delay constraints This is not file sharing, delay is the design objective
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 4
Outline of Talk
P2P streaming systems, definitions
Protocols for Chunk Trading
Push & Pull, why both?
Delay Aware Peer Selection
Wrap-Up and Future Work
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 5
P2P Streaming Systems
As in the previous talk ... yes, we do talk to each other before presentations 1 source generates media chunks at Bs Mbit/s Peers receive and transmit chunks
The system is unstructured and chunks swarms through the overlay topology No fixed distribution tree Each peer is connected to a subset of the other peers
Neighborhoods are stable (in this study)
Peers are autonomous and not synchronized: they evolve solely based on the protocol, no other coordination supposed
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 6
Network Model We consider an n-regular
topology with symmetric connectivity Good approx. of a random
topology Easy to construct and maintain
Access is the bottleneck and ADSL-like
Both upload and download bandwidth follow a simplified reservation sharing mechanism (on UDP)
Congestion is avoided setting a maximum to parallel transmissions
3-regular topology
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 7
Chunk Trading Each peer
Receives chunks from the other peers Redistributes chunks to neighbour peers
Two main drivers of the Chunk Trading Logic: The protocol The scheduling (local choices of Peers and Chunks)
We focus here on the protocol Scheduling is “plain” (or trivial if you prefer)
Major “fights” discuss benefits of Push or Pull-based protocols (these latter called also data-driven ... with no reason )
Indeed there is no reason to use one OR the other, they can be mixed in the same application
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 8
Traded Push & Pull
Push can also be “blind” (many studies assume so), but duplicated chunks waste bandwidth
Peers to trade with are chosen at random, or may follow some “logic”: distance, av. bandwidth, delay, ...
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 9
Node Active and Passive BehaviorPeers transmit and receive chuncks
Peers transmit offers/requests: they are active protocol entities (or clients in Internet terminology)
Peers satisfy offers/requests: they are passive protocol entities(or servers in Internet terminology)
the node startsrequests/offers
the node receivesrequests/offers
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 10
Selecting Peers and Chunks Peers are selected in the neighborhood
At random – R Following a distribution weighted by 1/RTT: Delay Aware – D Selected peers are “poisoned” to avoid deterministic patterns and
starvations (e.g. one peer very close and the others far away) In Push: chunks are offered selecting the most recent
available In Pull: chunks are requested selecting the most
needed, i.e., those closer to the playout time (or oldest) Push and Pull phases are asynchronous and compete for
the bandwidth resources Offers are put forward and requests satisfied only if there are
available resources on the local link Model suitable for applications that enforce some sort of shaping
Signaling and data transmission are sequential
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 11
The role of Push and Pull: Diffusion delay distribution
RTT = [10,250] ms = 1,1Bp = 1.9 ... 3.4 BsPeer Choice = R
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 12
The impact of R/D, parallel tx. and window
RTT = [10,250] msD
R
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 13
Tail Behavior: 95-th percentile, different RTTs
Delay Aware
bandwidth reduction
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 14
Summary and Future Work – Summary
Analysis and insight in a flexible protocol (Push/Pull) for P2P streaming
Assessment of the impact (very positive) of selecting peers in your neighborhood based on their RTT, one of the few easy-to-measure network characteristics
Study of some tuning parameters of the basic protocol
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010 15
Summary and Future Work – Work ... Implementation of Push/Pull in GRAPES libraries: done!
http://napa-wine.eu Implementation of P2PTV streamers in NAPA-WINE
peers based on Push/Pull protocols, to compare with other offer/select protocols: under wayhttp://napa-wine.eu
Exploration of tradeoffs between building delay-aware topologies with random peer choice, vs. random topologies vs delay-aware peers selection: to be done
Integration of delay-aware techniques with other network-aware strategies: in discussion & first tests
Improvements and open issues for parallel signaling and chunk transfer: under way (both simulation & implementation)
www.disi.unitn.it/locigno ICC 2010 - NGS, Cape Town, June 26 2010
THE END
Thank you!
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