a fully connected network, complete topology or full mesh topology is a network topology in which there is a direct link between all pairs of nodes. in a fully connected network with n nodes, there are n(n-1)/2 direct links. networks designed with this topology are usually very expensive to set up, but provide a high degree of reliability due to the multiple paths for data that are provided by the large number of redundant links between nodes. this topology is mostly seen in military applications. however, it can also be seen in the file sharing protocol bittorrent in which users connect to other users in the "swarm" by allowing each user sharing the file to connect to other users also involved. often in actual usage of bittorrent any given individual node is rarely connected to every single other node as in a true fully connected network but the protocol does allow for the possibility for any one node to connect to any other node when sharing files.