Measure and Model P2P Streaming System by Buffer Bitmap Yishuai Chen*, Changjia Chen, Chunxi Li Network Research Group, Telecom Lab, Beijing Jiaotong University

Index Introduction Measurement of PPLive Analysis Modeling

Introduction

Measurement of PPLive

Analysis

Modeling

Mesh-Based P2P Streaming System Media Server Service Provider User 1 User 2 User 3 User 4 Chunk 1: Chunk 2

Local Buffer For local playback Sliding window like Limited Size 10s-100s

For local playback

Sliding window like

Limited Size

10s-100s

Buffer & Buffer Bitmap Measurable

Virtual Buffer End: Media Server Contain: the newest uploaded chunk Head: Peer buffer head Contain: the chunk shall be rejected Bitmap of virtual buffer: Peer’s buffer bitmap + ‘0’ appended until the buffer end

End: Media Server

Contain: the newest uploaded chunk

Head: Peer buffer head

Contain: the chunk shall be rejected

Bitmap of virtual buffer:

Peer’s buffer bitmap + ‘0’ appended until the buffer end

Measurement of PPLive Behavior: cache rejection sync with media server’s chunk uploading Rejection rate of a chunk = its uploading rate at media server Theorem 1. A fixed-duration buffer When constant rate uploading, fixed length buffer Smoothly transit when rate changes

Behavior:

cache rejection sync with media server’s chunk uploading

Rejection rate of a chunk = its uploading rate at media server

Theorem 1. A fixed-duration buffer

When constant rate uploading, fixed length buffer

Smoothly transit when rate changes

Analysis Method Bitmap Matrix Chunk Position: m Occupancy Probability: P m

Bitmap Matrix

Chunk Position: m

Occupancy Probability: P m

P m : is a network characteristic Peers in same network has similar P m

N ( t ) chunk uploaded at t =0 N(t) ： the amount of peers who have obtained this chunk at time t Reflects the propagation procedure of a chunk P m = N ( m/r )/ M 0 M 0 : network size r : playback rate.

chunk uploaded at t =0

N(t) ： the amount of peers who have obtained this chunk at time t

Reflects the propagation procedure of a chunk

P m = N ( m/r )/ M 0

M 0 : network size

r : playback rate.

Model Two phases Each phase is exponential

Two phases

Each phase is exponential

Model Verification

Thanks!