1582: Extensions to RIP to Support Demand Circuits.

Running routing protocols on connection oriented Public Data Networks, for example X.25 packet switched networks or ISDN, can be expensive if the standard form of periodic broadcasting of routing information is adhered to. The high cost arises because a connection has to all practical intents and purposes be kept open to every destination to which routing information is to be sent, whether or not it is being used to carry user data.