A small world architecture for p2p networks

1. A small world architecture for p2p networks Hcai.chen

2. Table of content • Related work • Algorithm description • Future work

3. Related work • Resource discovery in peer-to-peer networks • Small world overlay in peer-to-peer networks

4. Resource discovery in peer-to-peer networks • Structured p2p networks distributed hash tables problem: the cost of maintaining a consistent distributed in most index is too high in dynamic environments. • Unstructured p2p networks flooding problem: it either require a high overhead or generate massive network traffic.

5. Small world overlay in peer-to-peer networks • Most studies of constructing small world behaviors in p2p systems are based on the concept of clustering peer nodes into groups, communities, or clusters. • The Small World Overlay P2P protocol is built on top of existing structured P2P networks by classifying peer nodes into clusters, which achieves improved lookup performance over existing protocols.

6. Small world overlay in peer-to-peer networks • P.Triantafillou divided a Chord ring into smaller sub-rings to achieve better performance. • Liu et al. used a rigorous binary tree code algorithm to improve search capability by organizing peer nodes into different peer groups.

7. Algorithm description • Intra-group content searching • Inter-group content searching • Group information maintenance

8. Intra-group content searching • Each shared file in SWAN is published by an associated content advertisement (e.g. filename, file size, file description, address of the host node). • The advertisement lookup procedure involves two steps: a structured P2P search followed by an unstructured P2P search. The requesting peer node firstly searches the target peer nodes generated from the same hash function . If the requested advertisement cannot be found in the target peer node (e.g. the target peer node is offline at the moment), the requesting peer node will continue to search the neighbors of the target peer node in the member list within a distance d (unstructured P2P search), and can find the requested files with a high probability.

9. Intra-group content searching

10. Inter-group content searching • a new peer group is advertised by an XML based group advertisement (e.g. group ID, group name, addresses of contact points, and the description of the peer group). • When a peer node receives a peer group advertisement, it will push the advertisement to a target peer node in the peer group according to the hash value of the name of the peer group as well as the neighbors of the target peer node within a specific distance d to increase the probability of discovery of the advertisement. Similarly to the intra-group content searching, if the request originator cannot find the requested advertisement in the structured P2P search procedure due to a high network churn, the requested advertisement can still be found in the neighbors of the target peer node.

11. Inter-group content searching Inter-peer group link formation

12. Group information maintenance • When a peer node reconnects to the network, it will multicast notifications to its neighbors with a time stamp marking the time it last left the network. The neighbors will select and send back the content advertisements with the publishing dates later than the time of the time stamp, and the hash values of the names of advertisements pointing to the peer node (all peer nodes use the synchronized network time).

13. Group information maintenance • When a peer node intends to join a new peer group, it can utilize the peer group search protocol to find the relevant peer group advertisement and initialize connections to the peer group. In order to keep the member list up to date, each peer node periodically and probabilistically selects a given number of peer nodes and reconciles the member list of the peer group.

14. Future work • Further research on the small world architecture for p2p networks: Analyze the characteristics and the fault tolerant.