Enabling Remote Loopback

You can enable remote loopback capability on frame-based T3 interfaces configured to use C-bit framing. Remote loopback is not supported on E3 ATM, E3 FRAME, and T3 ATM interfaces.

For a list of the modules that support remote loopback, see ERX Module Guide, Appendix A, Module Protocol Support.

To enable remote loopback:

1. Change the clock source to internal.

   host1(config-controll)#clock source internal module

2. Ensure that the line is configured to use C-bit framing, which is the default for frame-based T3 interfaces.

   host1(config-controll)#framing c-bit

3. Configure one of the following loopback tests:
   • Set the loopback to remote to request that a remote device connected on a T3 interface enter into a loopback.

     host1(config-controll)#loopback remote

   • Configure the T3 interface to enable or disable the ability to enter into a loopback initiated by a remote device, as follows:
     • Issue the equipment customer loopback command to enable the router to enter into loopback when it receives an appropriate signal from the remote device.

       host1(config-controll)#equipment customer loopback

     • Issue the equipment network loopback command to disable the ability to enter into loopback initiated by a remote device.

       host1(config-controll)#equipment network loopback

equipment loopback

• Use to enable or disable the router’s ability to enter into a loopback initiated by a remote device connected on a T3 interface.

  Note: Remote loopback is available only on frame-based T3 interfaces configured to use C-bit framing.

• Specify one of the following loopback options:
  • customer—Enables the router to enter into loopback when it receives an appropriate signal from the remote interface
  • network—Disables the router’s ability to enter into loopback when it receives an appropriate signal from the remote interface
• Examples

  host1(config-controll)#equipment customer loopback

  host1(config-controll)#equipment network loopback

• Use the no version to disable the router’s ability to be placed in loopback by the remote device.
• See equipment loopback.

loopback

• Use to configure a loopback.
• Specify one of the following loopback options:
  • local—Loops the data back toward the router; on supported line modules, also sends an alarm indication signal (AIS) out toward the network
  • network—Loops the data toward the network before the framer processes the data
  • payload—Loops the data toward the network after the framer processes the data
  • remote—Sends a far end alarm code in the C-bit framing, as defined in ANSI T1.404, to notify the remote end to activate or (when you use the no version) deactivate the line loopback

    Note: Remote loopback is available only on frame-based T3 interfaces configured to use C-bit framing.

• Example

  host1(config-controll)#loopback local

• Use the no version to restore the default configuration, no loopback.
• See loopback.

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