48
controller T1 1/0:11
framing esf
channel-group 20 timeslots 1-24 speed 64
!
controller T1 1/0:12
framing esf
channel-group 20 timeslots 1-24 speed 64
!
controller T1 1/0:13
framing esf
channel-group 20 timeslots 1-24 speed 64
!
controller T1 1/0:14
framing esf
channel-group 20 timeslots 1-24 speed 64
!
controller T1 1/0:15
framing esf
channel-group 20 timeslots 1-24 speed 64
If you are having trouble:
•If the Layer 1 Status is “Deactivated,” make sure that the cable connection is not loose or disconnected. This status message
indicates a problem at the physical layer.
•There may be a problem with your telco, or the framing and line code types you entered may not match your telco’s. A
Layer 2 error indicates that the universal gateway cannot communicate with the telco. There is a problem at the data link
layer.
Configuring the D Channels for ISDN Signaling
The ISDN D channels carry the control and signaling information for your ISDN calls—for both circuit-switched data calls, and
analog modem calls.
The D channel notifies the central office switch to send the incoming call to particular time slots on the Cisco universal gateway.
Each one of the B channels carries data or voice. The D channel carries signaling for the B channels. The D channel identifies if
the call is a circuit-switched digital call or an analog modem call. Analog modem calls are decoded and then sent off to the
onboard modems. Circuit-switched digital calls are directly relayed to the ISDN processor in the gateway.
When you configured your ISDN PRI on the CT1 or CE1 controller, you automatically created a serial interface that corresponds
to the PRI group time slots. This interface is a logical entity that is associated with the specific controller. After the serial
interface is created, you must configure the D channel serial interface that carries signaling. The configuration applies to all the
PRI B channels (time slots) for that PRI group.
The following table shows the logical contents of a ISDN PRI interface used in a T1 network configuration. The logical contents
includes 23 B channels, one D channel, 24 time slots, and 24 virtual serial interfaces (total number of Bs + D).