A practical hybrid mechanism for peer discovery

Peer discovery is a basic service of P2P applications. It enables peers in a P2P application to locate one another so they can interact. The connectivity of a P2P system depends on the efficiency of the peer discovery mechanism adopted. There are three categories of peer discovery mechanisms. Most P2P applications implement one of them. They will work perfectly in a transparent net work, where peers can communicate freely. On the Internet, peers behind NAT gateways have very poor connectivity. They are often discriminated as ´second´ or even cannot interact within their residing sub-network. In order to make use of all possible peer resources, this paper describes a hybrid discovery mechanism. Furthermore, by making full use of the local IP interface in addition, every potential connection within a sub-network is unearthed. The simulation results also prove the efficiency of the presented mechanism.