A fully-connected graph.
Originally <a href="//commons.wikimedia.org/wiki/User:Foobaz" title="User:Foobaz">User:Foobaz</a>
This is a vector conversion of <a href="//commons.wikimedia.org/wiki/File:NetworkTopology-FullyConnected.png" title="File:NetworkTopology-FullyConnected.png">File:NetworkTopology-FullyConnected.png</a>