6.2 Dialer Profile
6.2.5 Dialer pool and physical interfaces
Each dialer interface references a dialer pool, which is a group of one or more physical interfaces associated with a dialer profile.

A physical interface can belong to multiple dialer pools. Contention for a specific physical interface is resolved with a configured priority, which is optional.

A virtual interface must be associated with a dialer pool. The dialer is a group of one or many physical interfaces in charge of placing the call.

Dialer profiles support PPP or HDLC encapsulation, PPP authentication (PAP or CHAP), and MLP, if used. All other settings are part of the dialer interface configuration that is applied to the physical interface on a per-call basis.

Use the dialer pool-member command to assign a physical interface to a dialer pool. You can assign an interface to multiple dialer pools by using this command to specify several dialer-pool numbers.

Use the priority option of this command to set the interface priority within a dialer pool, which is used only when dialing out. You can use a combination of synchronous, serial, BRI, or PRI interfaces with dialer pools. The following table lists the commands used to set the pool membership priority.

Encapsulation type, PPP authentication, and MLP are all configured on the physical interface. This association to the physical interface is important because before an incoming call is bound to a dialer interface, the router negotiates the Link Control Protocol (LCP) layer of PPP (which includes the authentication type and whether PPP multilink will be used). Then, the router authenticates the remote router with the method specified (PAP or CHAP). Based on the response to this challenge, the router will try to bind the call to the correct dialer profile. At this point, the dialer profile is applied and takes over, and the call is completed and the routers are connected.