CCIE Fundamentals: Network Design and Case Studies, Second Edition

Chapter 19. Dial-on-Demand Routing

Edited by Salman Asad

Cisco's dial-on-demand routing (DDR) feature enables you to use existing telephone lines to form a wide area network (WAN). While using existing telephone lines, you can analyze traffic patterns to determine whether the installation of leased lines is appropriate. DDR provides significant cost savings over leased lines for links that are utilized for only a few hours each day or that experience low traffic flow.

DDR over serial lines requires the use of dialing devices that support V.25bis. V.25bis is an International Telecommunication Union Telecommunication (ITU-T) Standardization Sector standard for in-band signaling to bit-synchronous data communications equipment (DCE) devices. A variety ...