1. Configuring DDR Backup using BRIs and Dialer Watch

2. Purpose
The use of an ISDN Basic Rate Interface (BRI) line to back up a serial connection using the Dialer Watch feature.

3. Configuring DDR backup
Two steps:
1. Configure the DDR with either legacy DDR or dialer profiles.
2. Configure the router to initiate the backup DDR connection when the primary link fails. (Dialer Watch)

4. Dialer Watch Operation
Pros
It is useful for a multiple backup scenario
It is independent of line protocol status
It is dynamic routing protocol independent
It is encapsulation independent
It dials immediately upon the loss of the primary route

5. Dialer Watch Cons This is more difficult to configure
It requires a routing protocol
It is dependent upon the routing protocol convergence time
Dialer Watch was unstable until Cisco IOS Software Release 12.1(7)

6. BRI0/0
BRI0/0 S0 S1
E0/0

16. BRI0/0
BRI0/0 S0 S1
E0/0