The dialer interface, dln, is
a logical interface for configuring properties for modem connections.
You can configure multiple dialer interfaces on a services gateway.
A dialer interface and a dialer pool (which includes the physical
interface) are bound together in a dialer profile.
The following rules apply when you configure dialer interfaces
for 3G wireless modem connections:
The dialer interface must be configured to to use the
default Point-to-Point Protocol (PPP) encapsulation. You cannot configure
Cisco High-Level Data Link Control (HDLC) or Multilink PPP (MLPPP)
encapsulation on dialer interfaces.
You cannot configure the dialer interface as a constituent
link in a multilink bundle.
You cannot configure any dial-in options for the dialer
interface.
You configure the following for a dialer interface:
A dialer pool to which the physical interface belongs.
Source IP address for the dialer interface.
Dial string (optional) is the destination number to be
dialed.
Authentication, for GSM HSDPA 3G wireless modem cards.
For GSM HSDPA 3G wireless modems, you configure a dialer interface
to support authentication through Challenge Handshake Authentication
Protocol (CHAP) or Password Authentication Protocol (PAP).
CHAP is a server-driven, three-step authentication method that
depends on a shared secret password that resides on both the server
and the client. When you enable CHAP on a dialer interface, the device
can authenticate its peer and be authenticated by its peer.
PAP allows a simple method for a peer to establish its identity
using a two-way handshake during initial link establishment. After
the link is established, an identification and password pair is repeatedly
sent by the peer to the authenticator until authentication is acknowledged
or the connection is terminated.
Backup, Dialer Filter, and Dialer Watch
The dialer interface can perform backup, dialer filter, and
dialer watch functions, but these operations are mutually exclusive.
You can configure a single dialer interface to operate in only one
of the following ways:
As a backup interface for a single primary WAN connection.
The dialer interfaces are activated only when the primary interface
fails. The 3G wireless modem backup connectivity is supported on all
interfaces except ls-0/0/0.
As a dialer filter. Dialer filter enables the 3G wireless
modem connection to be activated only when specific network traffic
is sent on the backup WAN link. You configure a firewall rule with
the dialer filter option, and then apply the dialer filter to the
dialer interface.
As a dialer watch interface. With dialer watch, the services
gateway monitors the status of a specified route and if the route
disappears, the dialer interface initiates the 3G wireless modem connection
as a backup connection. To configure dialer watch, you first add the
routes to be monitored to a watch list in a dialer interface; specify
a dialer pool for this configuration. Then configure the 3G wireless
modem interface to use the dialer pool.
Operating Parameters
You can also specify optional operating parameters for the dialer
interface:
Activation delay—Number of seconds after the primary
interface is down before the backup interface is activated. The default
value is 0 seconds, and the maximum value is 60 seconds. Use this
option only if dialer watch is configured.
Deactivation delay—Number of seconds after the primary
interface is up before the backup interface is deactivated. The default
value is 0 seconds, and the maximum value is 60 seconds. Use this
option only if dialer watch is configured.
Idle timeout—Number of seconds the connection remains
idle before disconnecting. The default value is 120 seconds, and the
range is from 0 to 4294967295 seconds.
Initial route check—Number of seconds before the
primary interface is checked to see if it is up. The default value
is 120 seconds, and the range is from 1 to 300 seconds.
