Testing at the T3 Layer

To enable testing at the T3 layer:

1. Change the clock source to internal.

   host1(config-controll)#clock source internal module

2. Configure one of the following tests:
   • Set the loopback to local to test the line without connecting to the network.

     host1(config-controll)#loopback local

   • Set the loopback to network to test the line connected to the network.

     host1(config-controll)#loopback network line

3. (Optional) Configure one of the following tests for remote loopback:
   • 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

4. Configure the line to run bit error rate tests.

   host1(config-controll)#bert pattern 2^15 time 20

bert

• Use to enable bit error rate tests using the specified pattern on a channelized T3 interface.
• Unlike other configuration commands, bert is not stored in NVRAM.
• Specify one of the following test patterns:
  • 0s—Repetitive test pattern of all zeros, 00000...
  • 1s—Repetitive test pattern of all ones, 11111...
  • 2^9—Pseudorandom test pattern, 511 bits in length
  • 2^11—Pseudorandom test pattern, 2047 bits in length
  • 2^15—Pseudorandom test pattern, 32,767 bits in length
  • 2^20—Pseudorandom test pattern, 1,048,575 bits in length
  • 2^20-QRSS—Pseudorandom QRSS test pattern, 1,048,575 bits in length
  • 2^23—Pseudorandom test pattern, 8,388,607 bits in length
  • alt-0-1—Repetitive alternating test pattern of zeros and ones, 01010101...
• Specify the duration of the test in the range 1–1440 minutes.
• Example

  host1(config-controll)#bert pattern 2^15 interval 20

• Use the no version to stop the test that is running.
• See bert.

equipment loopback

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

  Note: Remote loopback is available only on channelized 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 channelized 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.