Peer-to-Peer Networks as a Distribution and Publishing

Model

Jorn De Boever (june 14, 2007)

2

Outline of the presentation

Introduction

Characteristics and Challenges of Peer-to-Peer

Peer-to-Peer Applications

Classification of Peer-to-Peer Architectures

Peer-to-Peer Criteria and Openness

Discussion: Q&A

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Introduction

Mass content distribution

Inefficient and costly.

Commercialization of internet

Mass medium.

Mostly client/server.

Foundation of peer-to-peer: penetration broadband internet, reliability of connections, capacity of user equipment, evolution compression technology, and etc.

Increasing demand for multimedia content.

Conclusion: traditional distribution models under pressure.

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Outline of the presentation

Introduction

Characteristics and Challenges of Peer-to-Peer

Peer-to-Peer Applications

Classification of Peer-to-Peer Architectures

Peer-to-Peer Criteria and Openness

Discussion: Q&A

5

Characteristics and Challenges of Peer-to-Peer

Peer-to-peer principles

Sharing resources in a peer-to-peer manner

Partial or full decentralization

Self organizing systems depending on level of decentralization

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Characteristics and Challenges of Peer-to-Peer

Peer-to-peer versus client/server

Client/server:

Easy to manage and control (centralized)

Negative network externalities:

limited scalability,

expensive distribution model,

danger for bottlenecks and single points of failure.

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Characteristics and Challenges of Peer-to-Peer

Peer-to-peer versus client/server

Peer-to-Peer:

Scalability, decentralization, transient connectivity, cost efficiency, fault tolerance, self organization, resource sharing

Servents SERVer + cliENTS

Positive network externalities:

Additional users = additional resources

Challenges: transient connectivity, security, availability of resources and scalability

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Outline of the presentation

Introduction

Characteristics and Challenges of Peer-to-Peer

Peer-to-Peer Applications

Classification of Peer-to-Peer Architectures

Peer-to-Peer Criteria and Openness

Discussion: Q&A

9

Peer-to-Peer Applications

Communication: IM and Telephony

Grid computing

Collaborative applications

File sharing and content distribution

Wireless and ubiquitous peer-to-peer

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Outline of the presentation

Introduction

Characteristics and Challenges of Peer-to-Peer

Peer-to-Peer Applications

Classification of Peer-to-Peer Architectures

Peer-to-Peer Criteria and Openness

Discussion: Q&A

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Classification of Peer-to-Peer Architectures

Degree of decentralization

Centralized

Decentralized

Hybrid

Degree of structure

Unstructured

Structured

Centralized Decentralized Hybrid

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Classification of Peer-to-Peer Architectures

Centralized unstructured: e.g. Napster

Central directory server

Search process centralized (via server)

Exchange of data occurs in peer-to-peer manner

B C D

E

A

ServerQuery

D

?

Download

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Classification of Peer-to-Peer Architectures

Pure decentralized unstructured: e.g. Gnutella 0.4

No centralized component

Node functions: client, server, router, cache and search

Complete self organization

A

B

C

D

QH

QH

QH

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Classification of Peer-to-Peer Architectures

Hybrid unstructured: e.g. Gnutella 0.6

Convergence: combining advantages and circumventing the drawbacks of centralized and pure decentralized systems.

Introducing hierarchy in the system via super nodes.

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Classification of Peer-to-Peer Architectures

Pure decentralized structured: e.g. Chord

Self organizing without centralized components.

Structured: resources and nodes are mapped into address space.

Indexing of address space is distributed among nodes (DHT’s).

Advantages:

Efficient search mechanism

Disadvantages:

Updating routing tables causes load

Keyword-based search is not supported

Load balancing

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Outline of the presentation

Introduction

Characteristics and Challenges of Peer-to-Peer

Peer-to-Peer Applications

Classification of Peer-to-Peer Architectures

Peer-to-Peer Criteria and Openness

Discussion: Q&A

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Peer-to-Peer Criteria and Openness

When is a peer-to-peer solution appropriate?

Technical/business criteria

Cost of ownership.

Scalability.

Performance.

Peer-to-peer is a bandwidth saving distribution model and not a content model.

Social criteria:

Critical mass

Online available peers

Quantitative and qualitative availability

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Peer-to-Peer Criteria and Openness

When is a peer-to-peer solution appropriate?

Peer-to-peer only appropriate for mass content distribution? What about small user communities?

Peer-to-peer might be possible if:

Peers have strong ties and similar interests.

Peers are simultaneously online enough.

Incentives to cooperate are provided.

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Peer-to-Peer Criteria and Openness

When is a peer-to-peer solution appropriate?

Peer-to-peer and openness: open content, open access.

Content is free to users, distribution is expensive to content providers.

Existing systems: e.g. Lionshare, Comtella, Edutella.

Peer-to-peer appropriate for open initiatives if it meets peer-to-peer criteria.

If peer-to-peer is successful for open projects, storage and bandwidth costs will decrease.

Decreasing resource expenses reduce the barriers for open initiatives which can lead to more accessible content.

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Outline of the presentation

Introduction

Characteristics and Challenges of Peer-to-Peer

Peer-to-Peer Applications

Classification of Peer-to-Peer Architectures

Peer-to-Peer Criteria and Openness

Discussion: Q&A

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Discussion: Q&A

Conclusions

Peer-to-peer might provide solutions for some of the flaws of client/server networks.

Peer-to-peer is more than file sharing.

Classification based on degree of decentralization and structure.

Criteria for peer-to-peer solutions.

2007: the year of the arrival of legal peer-to-peer systems?

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Questions?

Jorn De Boever – jorn.deboever@soc.kuleuven.be