|
If no modem is specified
for a particular line and you have provided the modem autoconfigure
discovery command, the access
server attempts to autodiscover the type of modem to which it is
attached. The access server determines the type of modem by sending
AT commands to the modem and evaluating the response. The Cisco IOS
software initially tries the first of the modemcap strings to see if
the modem initializes properly. If not, the Cisco IOS software
cycles to the next string and repeats the process until the
appropriate string is found. Usually, if none of the strings
properly initialize the modem, you must manually configure the
modem.
Sometimes, the router fails to recognize a modem, even though it might be part of the modemcap list.
If you have verified that your modem can be configured by using an
initialization string from one of the existing scripts, you can
issue the
modem autoconfigure type
command, as explained in the
next section.
The following is an example of the
modem autoconfigure discovery command:
Router(config)#line 1 16
Router(config-line)#modem autoconfigure discovery
This command instructs the access server to do the following on lines 1 though 16:
-
Send the AT string at various baud rates until it receives an OK.
-
Send a variety of AT
commands that attempt to receive a complete identification of
the modem from the access server modem capabilities database.
The specific modemcap
entries found on a particular system are determined by the hardware
and Cisco IOS software version that are installed. Whenever
possible, specify a modem type to eliminate the router overhead when
modem autodiscovery is used. If you list a specific modem type,
initialization proceeds more quickly.
If the access server
cannot determine the modem type, the default modem entry is used.
Any modems that are not currently supported in the list can be
manually added to the list to be autodiscovered in future
communication, as you will see later in the section
"Fine-Tuning Modem Autoconfiguration."
|