Configuring The Loopback Mode For A T3 Controller; Configuring A T3 Controller To Respond To Remote Loopback Commands - Cisco 10000 Series Troubleshooting Manual

Chapter 6 Troubleshooting Serial Lines

Configuring the Loopback Mode for a T3 Controller

You can configure the loopback modes for a T3 controller by using the loopback command:
loopback [local | network | remote]
The default loopback mode for the T3 controller is no loopback.
To return the T3 controller to its default condition, use the no form of the command.
Examples:
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Configuring a T3 Controller to Respond to Remote Loopback Commands

The equipment customer loopback command allows a port to respond to loopback commands from
remote T3 equipment. The equipment network loopback causes a controller to ignore remote T3
loopback commands.
Syntax:
equipment [customer | network] loopback
Example:
To enable the controller's ability to respond to remote loopback requests, type:
Router(config)# controller T3 1/0/0
Router(config-controller)# equipment customer loopback
To prevent a controller from responding to remote loopback commands, type:
Router(config)# controller T3 1/0/0
Router(config-controller)# equipment network loopback
Remote loopbacks are only available when you use c-bit parity framing.
Note
OL-0439-02
Configure a T3 controller for local loopback.
Router(config)# controller T3 1/0/0
Router(config-controller)# loopback local
Local loopback simultaneously loops all channels toward the router and transmits a T3 AIS to the
network. You can use local loopback to diagnose problems with the port when isolated from the
network cables.
Configure a T3 port for network loopback.
Router(config)# controller T3 1/0/0
Router(config-controller)# loopback network
Network loopback loops the T3 line back towards the network and can be used to diagnose problems
with cables from the central switching office to the port.
Configure a T3 port for remote loopback.
Router(config)# controller T3 1/0/0
Router(config-controller)# loopback remote
Remote loopback sends a command to loop the T3 line at the far end (central office). It can be used
to diagnose problems with cables from the port adapter to the switching office.
Cisco 10000 Series Router Troubleshooting Guide
Using Loopback Tests
6-7