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 McCannes 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