Accelerating Peer-to-Peer Networks for Video Streaming Group 2 Andrew Doherty Aaron Wroblewski Raghav Chawla

Introduction Radial Reception Control Protocol (R2CP) enables real-time streaming of multimedia files over P2P networks R2CP uses RCP, which is similar to TCP but streamlined for P2P real-time usage New method of scheduling using rankings

Background and Motivation Peer-to-peer (P2P) overlay networks growing in popularity Widely used for file transfers, but not real-time streaming Most popular types of shared files are multimedia (music and video)

Streaming Model (Peer to Peer) 352x240 VCD 1.38 Mbps The Problem Statement Traditional Download Model Server Home PC 83 Minutes To Start Watching!! 1.5 Mbps ≥ 1.5 Mbps Streaming Model (Peer to Peer) 256 Kbps 1.5 Mbps Need 6 times available Bandwidth!

Challenges Bandwidth Requirements Ensuring In-Order Packet Arrival Peer Diversity Bottleneck Bandwidth Latency Peer Transience Users have short sessions in P2P Random Disconnects Bottleneck Bandwidth: Downstream: 1-10 Mbps Upstream: 100 Kbps – 5 Mbps Latency: less than 70ms – More than 280 Ms Transience: Short Sessions: Median Session is 60 mins. 60% active for no more than 10 mins.

R2CP Architecture RCP R2CP Engine Individual Paths TCP Clone Receiver Driven R2CP Engine Aggregate Connection Coordinates RCP Packet Scheduling

Dynamic Binding Sequence Numbers Loss Recovery Pipe Management Local -> Global Loss Recovery Coordinate losses with deadlines Pipe Management Reassign data from closed pipes to other pipes

Packet Scheduling Goals Methodology Ensure In-Sequence Delivery Minimize Packet Loss due to Buffer Overflows Missing Deadlines Methodology Congestion Control Rank Data Structure

Packet Scheduling Congestion Control Ranking Data-Structure RCP Notifies R2CP Engine when is has available slots in congestion window R2CP sends a data echo request to the source Ranking Data-Structure R2CP ranks each request by an approximated arrival time Request order is determined by rank and last packet requested

Protocol Operations R2CP Manages RCP Pipes Handle RCP Sender RCP pipes Sequence numbers Transmission/Receipt RCP Pipes Handle Congestion Windows Loss Notification RCP Sender Echos Data

Performance Evaluation Model Varied Network Conditions Compared performance of R2CP to: Ideal Conditions Multiple Sockets R2CP without RTT-scheduling

Results - Scalability Rate Differential Delay Differential Traffic Fluctuations

Results – Multipoint-to-Point Video Streaming Instantaneous Data Rate Playout Buffer Occupancy Resequencing Buffer Occupancy

Related Work “On multiple description streaming with content delivery networks,” in Proceedings of IEEE INFOCOM, June 2002 Proposes approach that uses multiple description coding for video streaming over multiple servers However P2P network users are not static so this doesn’t apply “Distributed video streaming over Internet,” in Proceedings of SPIE Multimedia Computing and Networking, Jan. 2002 Stream video from multiple distributed video servers Requires synchronization between servers “PROMISE: Peer-to-peer media streaming using CollectCast,” in Proceedings of ACM Multimedia, Nov. 2003 P2P streaming using multiple sources using UDP connection for streaming with TCP connection for sending control info Requires lower layer service and use of separate TCP connections for updates adds additional overhead

Critique Specific operation of the ranking/scheduling algorithm difficult to understand Examples would have been helpful Larger scope simulation with more sources with less ideal conditions

Summary and Conclusions R2CP is a viable method to enable real-time multimedia streaming over P2P networks R2CP is receiver-driven, requiring little overhead from multiple sources R2CP implements effective reliability and congestion control