Introduction to Dial-on-Demand Routing

DDR is the process by which a link is created on demand. As traffic needs to cross the WAN, a circuit is completed from the source router to the destination, allowing the traffic to cross.

DDR circuits are useful when you pay for access based on the amount of time the circuit remains up. Although DDR connections aren't as prevalent in the United States as they were in the mid 1990s, most of the rest of the world still pays for connections based on how long the connection remains up. For analog and ISDN connections, DDR is a useful option.