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This chapter describes how to configure dialer interfaces, which can be configured as the logical intermediary between one or more physical interfaces and another physical interface that is to function as backup. It includes the following main sections:
For a complete description of the dial backup commands in this chapter, see the Cisco IOS Dial Services Command Reference publication. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.
A backup interface is an interface that stays idle until certain circumstances occur; then it is activated. Dialer interfaces can be configured to use a specific dialing pool; in turn, physical interfaces can be configured to belong to the same dialing pool.
See the section "Dialer Profile for ISDN BRI Backing Up Two Leased Lines Example" at the end of this chapter for a comprehensive example of a dial backup interface using dialer profiles. In the example, one BRI functions as backup to two serial lines, and can make calls to two different destinations.
To configure a dialer interface and a specific physical interface to function as backup to other physical interfaces, perform the tasks in the following sections:
To configure the dialer interface that will be used as an intermediary between a physical interface that will function as backup interface and the interfaces that will use the backup, use the following commands beginning in global configuration mode:
| Command | Purpose | |
|---|---|---|
Step 1 | interface dialer number | Creates a dialer interface. |
Step2 | ip unnumbered loopback0 | Specifies IP unnumbered loopback. |
Step3 | encapsulation ppp | Specifies PPP encapsulation. |
Step4 | dialer remote-name username | Specifies the Challenge Handshake Authentication Protocol (CHAP) authentication name of the remote router. |
Step5 | dialer string dial-string | Specifies the remote destination to call. |
Step6 | dialer pool number | Specifies the dialing pool to use for calls to this destination. |
Step7 | dialer-group group-number | Assigns the dialer interface to a dialer group. |
To configure the physical interface that is to function as backup, use the following commands beginning in global configuration mode:
| Command | Purpose | |
|---|---|---|
Step1 | interface type number | Specifies the interface. |
Step2 | encapsulation ppp | Specifies PPP encapsulation. |
Step3 | dialer pool-member number | Makes the interface a member of the dialing pool that the dialer interface will use; make sure the number arguments have the same value. |
Step4 | ppp authentication chap | Specifies CHAP authentication. |
To configure one or more interfaces to use a backup interface, use the following commands beginning in global configuration mode:
| Command | Purpose | |
|---|---|---|
Step1 | interface type number | Specifies the interface to be backed up. |
Step2 | ip unnumbered loopback0 | Specifies IP unnumbered loopback. |
Step3 | backup interface dialer number | Specifies the backup interface. |
Step4 | backup delay enable-delay disable-delay | Specifies delay between the physical interface going down and the backup being enabled, and between the physical interface coming back up and the backup being disabled. |
The following example shows the configuration of a site that backs up two leased lines using one BRI. Two dialer interfaces are defined. Each serial (leased line) interface is configured to use one of the dialer interfaces as a backup. Both of the dialer interfaces use dialer pool 1, which has physical interface BRI 0 as a member. Thus, physical interface BRI 0 can back up two different serial interfaces and can make calls to two different sites.
interface dialer0 ip unnumbered loopback0 encapsulation ppp dialer remote-name Remote0 dialer pool 1 dialer string 5551212 dialer-group 1 interface dialer1 ip unnumbered loopback0 encapsulation ppp dialer remote-name Remote1 dialer pool 1 dialer string 5551234 dialer-group 1 interface bri 0 encapsulation PPP dialer pool-member 1 ppp authentication chap interface serial 0 ip unnumbered loopback0 backup interface dialer 0 backup delay 5 10 interface serial 1 ip unnumbered loopback0 backup interface dialer1 backup delay 5 10
Posted: Tue Jul 18 13:14:32 PDT 2000
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