Peer-to-peer authentication involves several tests. The application of message passwords and explicit acceptable neighbor lists has in the past improved the robustness of the route database. Routers SHOULD IMPLEMENT management controls that enable explicit listing of valid routing neighbors. Routers SHOULD IMPLEMENT peer-to-peer authentication for those routing protocols that support them.
Routers SHOULD validate routing neighbors based on their source address and the interface a message is received on; neighbors in a directly attached subnet SHOULD be restricted to communicate with the router via the interface that subnet is posited on or via unnumbered interfaces. Messages received on other interfaces SHOULD be silently discarded.
Security breaches and numerous routing problems are avoided by this basic testing.