Introduction

Discussed points in the meeting:

Distributed Hash Tables Criteria for DHT-based overlay network Multicast vs Overlay

Research Experience

Details

What is DHT ?

DHT: a class of decentralized distributed systems that provide look-up services.

How do we use DHT ?

When nodes ( terminals ) join into the overlay, specific IDs will be generated by applying SHA-1 algorithm for their IP addresses. SHA-1 is used to ensure the uniform distribution of nodes on the ID address spaces.

Whenever we need to find particular contents on a node with nodeID, the node IP address can be found by querying IDs on DHTs and ID address spaces.

In this case, the role of DHTs in P2P model is similar to the role of DNS servers in Client-Server model. The only difference is that the task of maintenance DHTs are shared among nodes but the task of maintenance DNS table is belonging to DNS servers.

What criteria do we concern when judging a specific DHT-based overlay network ?

Maximum number of hops: scalability of P2P network

Organization of the peer address space: uniform distribution in ID address space

Next-hop decision criteria: routing ability

Geometry of the overlay:

Overlay Maintenance: nodes management

Locality and topology awareness: routing ability

What differences between overlay and multicast?

Multicast network is built upon Overlay network

Overlay

Overlay networks are in charge of node managements, object location and routing, interconnection between peers.

P2P Overlays paradigm are selft-organization, role symmetry, resource sharing, scalability, peer autonomy, and resiliency.

Multicast

Multicast takes care of group management ( community management ). It allows several (m) nodes to transfer data, messages, information to other ( n ) nodes.

There are 3 main types of multicasting: IP Multicast, Application Level Management, and Hybrid Multicasting.

There are 2 types of building multicasts: mesh-based multicast and tree-based multicast.

Research objectives (16/08/2009 - 30/08/2009)

Mutlicast

1. Group Management

2. IP Multicasting / Application Level Multicasting / Hybrid Multicasting

3. D1.2 Document Modification.

Research Experience

Concepts ==> Roles of concepts in the project ==> Methods of applying these concepts.

Questions in Research

What are these concepts ?

Why do we need them ?

How can we use them ?