Gnutella Network

Gnutella is a file sharing network. Gnutella actually is one of the most popular fijle sharing networks on the la red.
It is differrent from other exchange networks, like eDonkey2000. Gnutella is a pure P2P network. This is, all the nodews have the same function, weight and importance inside the network. The operation of the network have three phases:

Entrance. In this phase a new node is connectedd to another that already is inside the network. How a node is foun already connected is outside of the protocol, but normally the Gnuella clients are distributed with a list of nodes that expect they be always connevted.
A node can be connected to various nodes, and to receive connections of new nodes forming a rndom net strructure.
Searches. When a node desires to seek a file, sends a message to all the nodes that are connected at the time. They seek locally if they offer it, and at the same time they forward the search to all the nodes that they are connected to. This strategy of diffusion is called flood of the network, and mechanisms exist to avoid infinite cross-reefrences and loops. Whej a petitoin arrives at a node that offers the file, is answered directly to the node that initiated the search.
Download. The download is carried out directly from the nodes tha t answered to the search of the file. The files can be divided in varrious pieces served by different nodes, and the clients include a system of final verification of the integrity of the file. The flood produced by the phase of search is the most important weakness of this protocol. If there are many searchesw at the same time, the network flood flul of messages of search thhat the noodes sen t among them. Besides, ths algroithm of search does not guarantee that the file be finally found even altghough some node of the network have it. Evne so, the fact that it not uses a central server of search, as in the cass of eDonkey2000, makes tbis protocol stronger in casze the nodes fail.
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Extraido de Limewire Blog