4000 Router Series Layer 2 - WAN Configuration Guide

Figure 35 Associations between physical interfaces, dialer bundles, and dialer interfaces in B-DDR

As shown in Figure 35, a physical interface can be assigned to multiple dialer bundles and serve

multiple dialer interfaces, but each dialer interface can belong to only one dialer bundle and be

configured with one dial string. The physical interfaces in a dialer bundle can be assigned different

priorities.

In the figure, interface Dialer 2 contains physical interfaces BRI 1/0, BRI 1/1, and Serial 2/1. Suppose

BRI 1/0 is assigned the priority of 100, BRI 1/1 the priority of 50, and Serial 2/1 the priority of 75.

Because BRI 1/0 has a higher priority over BRI 1/1 and Serial 2/1, it will be preferred when Dialer 2

places a call.

DDR features

Basic DDR features

Basic DDR offers the following features:

• Supporting a wide range of dialup interfaces, such as synchronous/asynchronous serial interface,

AUX port, ISDN BRI or PRI interface, and AM interface to accommodate different networking

requirements.

• Supporting link layer protocol PPP.

• Supporting IP on dialup interfaces.

• Supporting dynamic routing protocols, such as RIP and OSPF, on dialup interfaces.

• Providing flexible dialup interface backup.

• Allowing you to manage different modems on the user interface.

Callback through DDR

In callback, the called party originates a return call to the calling party. The calling party is the client and

the called party is the server. The callback client originates a call first, and the callback server decides

whether to originate a return call. If a callback is needed, the server will immediately disconnect and

originate a return call.

DDR callback offers the following benefits: