Peer-to-Peer Protocol (P2PP)
Peer-to-Peer Protocol is an Application-layer protocol that can be used to form and maintain an overlay among participant nodes. It provides mechanisms for nodes to join, leave, publish, or search for a resource-object in the overlay. It maintains information about nodes in a routing table. Because of potentially large content, a node's routing table only contains a subset of these nodes. If a node can't accomplish the request, it searches for one who can, by performing a nextHop operation to a destination from the routing table (recursive-routing).
Read more about Peer-to-Peer Protocol (P2PP): Basic Functions of The Protocol Are, Messages, Type-length-value Objects, Additional Information Fields, Response Codes, Request / Response Rules, Routing