Chapter 10. Designing DDR Networks
Edited by Salman Asad
Dial-on-demand routing (DDR) provides network connections across Public Switched Telephone Networks (PSTNs). Dedicated wide-area networks are typically implemented on leased lines or more modern service provider options such as Frame Relay, SMDS, or ATM. Dial-on-demand routing provides session control for wide-area connectivity over circuit-switched networks, which in turn provides on-demand services and decreased network costs.
DDR can be used over synchronous serial interfaces, Integrated Services Digital Network (ISDN) interfaces, or asynchronous serial interfaces. V.25bis and DTR dialing are used 0for Switched 56 CSU/DSUs, ISDN terminal adapters (TAs), or synchronous modems. Asynchronous ...