Information Technology Reference
In-Depth Information
Dialer profiles allow the configuration of physical interfaces to be separated from the logical
configuration required for a call, and they also allow the logical and physical configurations to be bound
together dynamically on a per-call basis.
A
dialer profile
consists of the following elements:
•
A
dialer interface
(a logical entity) configuration including one or more dial strings (each of which
is used to reach one destination subnetwork)
•
A
dialer map class
that defines all the characteristics for any call to the specified dial string
•
An ordered
dialer pool
of physical interfaces to be used by the dialer interface
All calls going to or from the same destination subnetwork use the same dialer profile.
A dialer interface configuration includes all settings needed to reach a specific destination subnetwork
(and any networks reached through it). Multiple dial strings can be specified for the same dialer
interface, each dial string being associated with a different dialer map-class. The dialer map class defines
all the characteristics for any call to the specified dial string. For example, the map class for one
destination might specify a 56-kbps ISDN speed; the map class for a different destination might specify
a 64-kbps ISDN speed.
Each dialer interface uses a dialer pool, a pool of physical interfaces ordered on the basis of the priority
assigned to each physical interface. A physical interface can belong to multiple dialer pools, with
contention being resolved by priority. ISDN BRI and PRI interfaces can set a limit on the minimum and
maximum number of B channels reserved by any dialer pools. A channel reserved by a dialer pool
remains idle until traffic is directed to the pool.
When dialer profiles are used to configure DDR, a physical interface has no configuration settings except
encapsulation and the dialer pools to which the interface belongs.
The preceding paragraph has one exception: Commands that apply before authentication is
complete must be configured on the physical (or BRI or PRI) interface, not on the dialer
profile. Dialer profiles do not copy PPP authentication commands (or LCP commands) to
the physical interface.
Note
Figure 16-9 shows a typical application of dialer profiles. Router A has dialer interface 1 for
dial-on-demand routing with subnetwork 1.1.1.0, and dialer interface 2 for dial-on-demand routing with
subnetwork 2.2.2.0. The IP address for dialer interface 1 is its address as a node in network 1.1.1.0; at
the same time, that IP address serves as the IP address of the physical interfaces used by the dialer
interface 1. Similarly, the IP address for dialer interface 2 is its address as a node in network 2.2.2.0.
