1

Modeling peer-peer file sharing systems

Ge, Z.; Figueiredo, D.R.; Sharad Jaiswal; Kurose, J.; Towsley, D.;

INFOCOM 2003. Twenty-Second Annual Joint Conference of the IEEE Computer and Communications Societies.

Presentation by Tony Sung, MC Lab, IE CUHK23th September 2004

2

Outline

Significance of the Paper

Modeling P2P Systems

Capturing the Parameters

The Results

Conclusion

3

Significance of the Paper

Mathematical Model that addresses

Scalability

Impact of freeloaders

Impact of imbalanced service capacity and file request load

4

Significance of the Paper

Results

Limited-scope flooding worsen performance

Freeloaders do not have significant impact

Centralized indexing approach can scale gracefully up to its capacity

Degradation due to replication-popularity mismatch is minor

5

Modeling P2P Systems

Modeling

6

Modeling P2P Systems

3 types of systems

CIA – Centralized Indexing Architecture

DIFA – Distributed Indexing with Flooding Architecture

DIHA – Distributed Indexing with Hashing Architecture

7

Modeling P2P Systems

A multiple class closed queuing network

C classes of peers: N = (N (1),…, N (C)) M number of distinct files sorted according to

availability

States Thinking, Querying,

Downloading, Offline

8

Modeling P2P Systems

9

Capturing the Parameters

Capturing Parameters

10

Capturing the Parameters

11

A single class case, C = 1, Na = (Na(1))

(Popularity, Zipf, assumed …)

(File service rate)

? (Common services’ service rate)

? (Query Failure Rate)

Capturing the Parameters

12

Common services’ service rate

CIA:

DIFA:

DIHA:

Capturing the Parameters

13

Query failure rate

CIA:

DIFA:

DIHA:

Capturing the Parameters

14

Freeloaders: 2 classes

Capturing the Parameters

15

Solving the model

Visiting Ratio

Service Demand

Bottleneck Queue

16

Results

Results

17

Results

Scalability

CIA

DIFA

DIHADIHA

CIA

DIFA

18

Results

Freeloader’s impact onsystem throughput

Non-freeloaderpopulation

19

Results

Freeloader’s impact onnon-freeloader throughput

Non-freeloaderpopulation

20

Results

Reason of DIFA’s poor performance

21

Results

Mismatch in file popularity and replication

22

Results

Mismatch in file popularity and replication

23

Conclusion

Simple, representative math. Model

Flexible across architectures

Dealt with different classes of peers

24

Results

Freeloader’s impact on system throughput- another perspective