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Configuration of the Attached Modem 83
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discovery--Autodiscover modem also uses the modem capabilities database, but in the
case of discover, it tries each modem type in the database as it looks for the proper
response to its query.
As you can see, the modem autoconfigure command relies on the modem capabilities
database, also known as the modemcap. The modem capabilities database has a listing of
modems and a generic initialization string for the modem type. The discovery of a modem using
the autoconfigure feature uses the initialization strings from each modem in the modem
capabilities database to discover the installed modem. If the modem is not in the database, it
fails, and the administrator has to manually add the modem to the database.
The use of the discovery feature is not recommended because of the overhead on the router.
Each time the line is reset, the modem is rediscovered. However, the discovery feature can be
used to initially learn the modem type if you are not geographically near the router and cannot
gather the information any other way. After discovery has taken place, the administrator should
use the type option to specify the entry in the modem capabilities database to use.
To discover a modem, the syntax would be as follows:
modem autoconfigure discovery
Again, once the modem type is determined, the final configuration for the router interface
should be as follows:
modem autoconfigure type entry_name_from_modemcap
This configuration eliminates unnecessary overhead on the router.
Use the show modemcap command to see the entries in the modemcap database. Example 4-7
demonstrates the output from the show modemcap command.
Example 4-7
show modemcap Command Output Reveals Modemcap Database Entries
BCRANrouter#show modemcap
default
codex_3260
usr_courier
usr_sportster
hayes_optima
global_village
viva
telebit_t3000
microcom_hdms
microcom_server
nec_v34
nec_v110
nec_piafs
cisco_v110
mica