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In this configuration example, the
branch office is using a Cisco 1600 series router to place an ISDN
BRI call to the central office router, which is a Cisco 3640 with a
PRI connection. The configuration commands relevant to ISDN and DDR
are in bold when you look at the show
running-config command for
each router.
Note: Click on the topology to
view the command outputs.
Examine the show
running-config command for
BranchA. The first task in configuring ISDN is to specify the ISDN
switch type. In this case, the 5ESS switch is being used. Just above
the ISDN switch type you will notice that we have configured the
username CentralA with password cisco. This is the username and
password used with PPP authentication between the branch router and
the central router.
The next task on BranchA is to
specify the interesting traffic. This is the traffic that will
generate a call to the central-site router. In this example, any IP
traffic will generate a call. This is specified in dialer-list 1 and
is applied to the BRI interface as dialer-group 1. Also on the BRI
interface, we have set the timeout value to 60 seconds. This means
that when the line is idle for 60 seconds, the call will disconnect.
Finally, we have mapped the central-site IP address to its phone
number. The 4000 phone number is a four-digit number that simulates
the use of an ISDN speed-dial service.
Now that the configuration is
complete, we can monitor the status of the router with the necessary
show commands.
Examine the show
running-config command for
CentralA. The authentication, dialer commands, and switch type are
all similar to what we just did at the BranchA router. The
difference here is that we have a PRI connection and must configure
the controller.
The controller configuration is
pretty straightforward. Framing, linecode, and timeslots must be
configured. The framing type is ESF while the line code is B8ZS. The
pri-group timeslots 1-24
command enables the interface to use all 24 channels. The final step
in this configuration is to configure the D channel, which is
interface serial 1/0:23.
Examine the
show
commands to see the status of the ISDN D channel and the PRI controller.
Finally, examine the debug commands under each router to further test connectivity between the two sites.
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