Overlay networks measurement for resource indexing under different routing scheme

Distribute hash table, abbr. as DHT, has provided a reliable and fast information exchange service in large scale P2P systems. There are two types of information indexing schemes in the implementation of real applications. One is that routing is separated from indexing, as in the case of eMule, and the other is that routing and indexing are combined together, as in the case of BitTorrent. This paper performs a comparative study of the information indexing scheme of DHT in eMule and BitTorrent. We have studied the relationship between the schemes and typical usage of the DHTs. Our major discovery is that the average number of index nodes for one single resource in the DHT of BitTorrent is one order of magnitude higher than that in the DHT of eMule. Furthermore, we have found that the main reason for such discrepancy is that, in BitTorrent application, the resource is related to a swarm, and a swarm tends to spread itself to more index nodes; Whereas in eMule, static index information such as keywords needs to be distributed among fewer index peers, so as to increase the high recall rate for users. In addition this paper also does a comparative study of the vulnerability of these two schemes with respect to certain security threats such as DDoS.