Specifications

52
Channelized and Electrical Interface Line Card Installation and Configuration
78-16417-02
Configuring and Troubleshooting Line Card Interfaces
• Remote loopback sends a command to loop the T3 line at the far end. It can be used to diagnose
problems with cables. The following example shows how to configure the T3 controller for remote
loopback. The T3 controller is on a 6-port channelized T3 (T1) line card in slot 6 and port 0 of the
Cisco 12000 Series Router.
Router(config)# controller T3 6/0
Router(config-controller)# loopback remote
Figure 20 shows examples of how data is transmitted and received in each loopback mode.
Figure 20 6CT3-SMB Line Card Loopback Modes
Shutting Down the T3 Controller
You can shut down the T3 controller on the 6CT3-SMB line card with the shutdown controller
configuration command. This command sends a DS3 idle signal toward the network. You can bring the
T3 controller back up with the no shutdown controller configuration command.
The following example is for a 6-port channelized T3 (T1) line card in slot 6/port 0 of a Cisco 12000
Series Router:
Router(config)# controller T3 6/0
Router(config-controller)# shutdown
Router(config-controller)#
Tx/Rx
HDLC
Tx DS1 framer
Rx x DS1 framer
38667
No loopback
LIU
Tx DS3 framer
Rx x DS3 framer
Tx/Rx
HDLC
Tx DS1 framer
Rx x DS1 framer
LIU
Tx DS3 framer
Rx x DS3 framer
Local loopback
Tx/Rx
HDLC
Tx DS1 framer
Rx x DS1 framer
LIU
Tx DS3 framer
Rx x DS3 framer
Line loopback
Tx/Rx
HDLC
Tx DS1 framer
Rx x DS1 framer
LIU
Tx DS3 framer
Rx x DS3 framer
Payload loopback
Tx DS1 framer
Rx x DS1 framer
Remote
host
Tx DS3 framer
Rx x DS3 framer
Remote loopback
Cable
LIU