Dial-on-Demand Routing
- Dial-on-Demand routing refers to a collection of Cisco features that allows two or more Cisco routers to establish a dynamic connection over simple dialup facilities on an as-needed basis and is used for low-volume, periodic network connections over an ISDN network or Public Switched Telephone Network.
There are five basic steps of DDR operation:- The route to the destination is determined
- Interesting packets dictate a DDR call
- The dialer information is looked up
- Traffic is transmitted
- The call is terminated
- There are three stages for configuring legacy DDR:
- Define the static route
- Specify interesting traffic
- Configure the dialer information
- When using static routes, all participating routers must have static routes defined so that they can reach the remote networks. This requirement is necessary because static routes replace routing updates
- Interesting traffic, which triggers a DDR call, is designated by an administrator and can be defined on the basis of a variety of criteria, such as protocol type or addresses for source or destination hosts.
- The dialer information configuration process consists of four steps:
- Select the physical interface for the dial-up line
- Configure its network address
- Configure the encapsulation type
- Link the interesting traffic definition to the interface
- To configure legacy DDR, define the static routes with the, ip route command, specify interesting traffic with the dialer list command, and configure dialer information with the dialer group command