Vertex is an implementation of the Q2Q protocol (sort of like P2P, but one 
better). There are a few moving parts in Vertex:

    * PTCP: a protocol which is nearly identical to TCP, but which runs over 
      UDP. This lets Q2Q penetrate most NAT configurations.
    * JUICE ([JU]ice [I]s [C]oncurrent [E]vents): a very simple but immensely 
      flexible protocol which forms the basis of the high-level aspects of Q2Q
    * vertex: a command line tool which exposes a few features useful in many 
      situations (such as registration and authentication) 

The Q2Q network has some decentralized features (there is no one server or 
company which can control all Q2Q addresses) and features of centralization 
(addresses beneath a particular domain are issued by a server for that domain; 
once issued, some activities require the server to be contacted again, while 
others do not). Vertex includes an identity server capable of hosting Q2Q 
addresses. 

WWW: http://divmod.org/trac/wiki/DivmodVertex