Cisco 3640 User Manual page 3

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Platforms
This feature is supported on the Cisco 3640 router.
Note
the Cisco 3620 router.
Prerequisites
Before you can configure a Cisco 3640 router to provide Modem over ISDN BRI connectivity, you
must perform the tasks listed below:
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At least one of the following Cisco BRI network modules:
— NM-4B-S/T—Four-port ISDN BRI network module, minimum version 800-01236-03
— NM-4B-U—Four-port ISDN BRI with integrated NT-1 network module, minimum version
800-01238-06
— NM-8B-S/T—Eight-port ISDN BRI network module, minimum version 800-01237-03
— NM-8B-U—Eight-port ISDN BRI with integrated NT-1 network module, minimum version
800-01239-06
The version level is available from the show diag command, which displays the version number
as the part number. If your BRI network module is a version lower than those cited above or you
need more details, see the Cisco Connection Online (CCO) Field Notice titled Using Digital
Modems with the Cisco 3600 Basic Rate Interface (BRI) Network Module Upgrade in the Access
Products index. If your existing Cisco BRI network module is one of those listed above and does
not support the Modem over ISDN BRI feature, Cisco will upgrade the module at no charge.
To support the Modem over ISDN BRI feature, V.90 modem portware—for instructions on
downloading this software or obtaining it otherwise, see the Cisco 3600 Series Modem Portware
Upgrade Configuration Note on CCO.
Due to Cisco 3620 slot limitations, the Modem over ISDN BRI feature is not supported on
Obtain BRI service from your telecommunications provider. The BRI line must be provisioned
at the switch to support voice calls.
Install a four-port or eight-port BRI network module into your Cisco router. Depending on the
type of network module and your BRI service, you might also need to install an external network
terminator (NT-1).
Install a supported digital modem network module into the Cisco 3640 router.
After the system comes up, make sure enough buffers are in the free list of the buffer pool that
matches the maximum transmission unit (MTU) of your BRI interface. If not, you must
reconfigure buffers so the BRI interfaces function properly. To check the MTU of your interfaces,
use the show interfaces bri command. The show buffers command displays the free buffer
space. Use the buffers global configuration command to make adjustments to initial buffer pool
settings and to the limits at which temporary buffers are created and destroyed.
Modem over ISDN BRI for the Cisco 3640 Router 3
Restrictions