Manualshelf

Hardware manual

ManualsBrandsCisco ManualsComputer equipment2525 - 2525 TR Router
31323334353637383940
loopback (T1 interface)
Interface Commands IR-139
To better diagnose T1 provisioning problems, you can place the the remote CSU or remote
SmartJack into loopback. The loopback remote line fdl interface configuration command allows
you to place either the CSU or the SmartJack into loopback:
• ansi—Places the CSU into loopback, per the ANSI T1.403 Specification
• bellcore—Places the SmartJack into loopback, per the TR-TSY-000312 Specification
When both are configured, transmission of LOF indication (yellow alarm) takes priority over
transmission of some FDL messages.
If the remote loopback appears not to be working, use the show cont t3 command to determine if
the given T1 is currently attempting to transmit a LOF indication (yellow alarm):
Router# show controllers t3 0/0/0:2
T3 0/0/0 is up.
CT3 H/W Version: 5, CT3 ROM Version: 1.2, CT3 F/W Version: 2.5.9
Mx H/W version: 2, Mx ucode ver: 1.34
T1 2 is down, speed: 1536 kbs, non-inverted data
timeslots: 1-24
FDL per AT&T 54016 spec.
Transmitter is sending LOF Indication.
Receiver is getting AIS.
If the transmitter is sending a LOF indication, as in the previous example, stop the transmission of
the LOF indication (yellow alarm) with the no t1 yellow generation configuration command as
shown in the following example:
Router(config)# controllers t3 0/0/0
Router(config-controll)# no t1 2 yellow generation
Router(config-controll)# ^D
To verify that the transmission of the LOF indication (yellow alarm) has stopped, use the
show cont t3 command:
Router# show cont t3 0/0/0:2
T3 0/0/0 is up.
CT3 H/W Version: 5, CT3 ROM Version: 1.2, CT3 F/W Version: 2.5.9
Mx H/W version: 2, Mx ucode ver: 1.34
T1 2 is down, speed: 1536 kbs, non-inverted data
timeslots: 1-24
FDL per AT&T 54016 spec.
Receiver is getting AIS.
Framing is ESF, Line Code is B8ZS, Clock Source is Internal.
Yellow Alarm Generation is disabled
Then retry the remote loopback command. When diagnosis is complete, remember to re-enable the
LOF indication (yellow alarm).
You can also loopback all the T1 channels by using the loopback (CT3IP) interface configuration
command.
Example
The following example configures T1 channel 5 for a local loopback:
interface serial 3/0/0:5
loopback local