Layered Peer-to-Peer Streaming Multimedia Operating and Networking System (MONET) Group Yi Cui and Klara Nahrstedt {yicui,

Motivation n Challenges –Asynchrony: Requests from different times –Heterogeneity : Stream of different qualities Internet EthernetDSL Dial-up Cable Modem Server Multicast-based Solutions – –They can address both asynchrony and heterogeneity – –But IP Multicast is not there

Conceptual Comparison IP Multicast Overlay Network

An Overlay-based (P2P) Solution n Asynchrony –Buffering on the end host n Heterogeneity –Layered Streaming Time B1B1 R1R1 R2R2 R3R3

Layered P2P Streaming H0H0 Server :02 Request time 2 Layer number 0 H1H : H2H : H3H :04 H4H : Outbound Bandwidth Inbound Bandwidth

This Problem is Hard n End Host Constraints –Network Constraint: A supplying peer has limited bandwidth –Data Constraint: A supplying peer may not have all layers of a stream –Operation Constraint: One cannot stream from too many supplying peers in parallel n Our goal –To maximize the overall streaming qualities of all peers subject to the above constraints

A Greedy Algorithm H1H1 H3H3 H2H2 layer number QkQk 0123 … QkQk HkHk H4H4 H1H1 H3H3 H2H … HkHk H4H4 H1H1 H3H3 H2H … HkHk H4H4 QkQk H1H1 H3H3 H2H … HkHk H4H4 from server H1H1 H3H3 H2H2 layer number 0123 … HkHk H4H4 QkQk H1H1 H3H3 H2H … HkHk H4H4 QkQk (a)(b)(c) (d)(e)(f)

Node Departure/Failure H1H1 H3H3 H2H2 layer number 0123 … HkHk H4H4 Failed layer number 0123 … H1H1 H3H3 HkHk H4H4 degraded quality

Experiments n Peer Classes –Modem/ISDN (50%) –Cable Modem/DSL (35%) –Ethernet (15%) n Stream Layer Setup –50 layers –Full-quality streaming rate 1Mbps

Overall Streaming Quality A new Metric: Quality Satisfaction Layered Streaming vs. Versioned Streaming Request Rate = 120 req/hr, Buffer Length = 5min

Server Cost Layered Streaming vs. Versioned Streaming Outbound/Inbound Ratio = 1, Buffer Length = 5min

Impact of Buffer Length Outbound/Inbound Ratio = 0.8

How many supplying peers are necessary? Outbound/Inbound Ratio = 1, Buffer Length = 5min

Layer Rate Heterogeneity n Flat Rate –r 0 =r 1 =r 2 =…=r n n Natural Number (10) –r 1 =2r 0, r 2 =3r 0, …, r n =(n+1)r 0 n Fibonacci (7) –r 1 =2r 0, r 2 =r 0 +r 1, …, r n =r n-1 +r n-2 n Exponential (6) –r 1 =2r 0, r 2 =2r 1, …, r n =2r n-1

Performance Comparisons Average Quality SatisfactionNumber of Supplying Peers Request Rate = 120 req/hr, Buffer Length = 5min

Conclusions n Evaluation –Scalable: saving server cost –Efficient: utilizing bandwidth resource of supplying peers –Optimal: maximizing quality satisfaction of all peers n Open Problems –Fairness –Robustness –Measurement and Statistical Study »Peer Class Population »Peer Network Characteristics »Peers’ Joining/Access Patterns

Base Layer Enhancement Layer 1 Enhancement Layer 2 Implementation n McCanne’s PVH CODEC from Berkeley Mash Toolkit

Implementation

NP-completeness n A special case –Single-Source Unsplittable Flow V S1S1 S2S2 S3S3 S4S4 R2R2 R3R3 R4R4 R5R Network Constraint: The inbound bandwidth of each receiving peer (R k ) allows it to receive the full-quality stream (# of layers = 10) Data Constraint: Each supplying peer (S k ) has all layers available Operation Constraint: Each peer can only stream from one supplying peer and get the missing layers from server