JUNOSe 9.1.x Physical Layer Configuration Guide > Configuring T3 and E3 Interfaces > Testing Interfaces

Testing Interfaces

Testing interfaces allows you to troubleshoot problems and to check the quality of links at various layers in the interface stack. The router supports the following test options:

• Transmission of BERT patterns to remote devices
• Local loopback—Loops the data back toward the router; on supported line modules, also sends an alarm indication signal (AIS) out toward the network
• Network loopback—Loops the data toward the network before the data reaches the frame
• Payload loopback—Loops the data toward the network after the framer processes the data
• Remote loopback—Provides the ability to:

• Request that remote devices enter into loopback
• Be placed in loopback by remote devices

Sending BERT Patterns

The router can send BERT patterns from different layers in the interface stack on frame-based T3 interfaces.

For a list of the modules that support bit error rate tests, see ERX Module Guide, Appendix A, Module Protocol Support.

To send BERT patterns:

1. Select a controller.

host1(config)#controller t3 3/2

2. Configure a specific layer in the interface to generate BERT patterns.

host1(config-controll)#bert pattern 2^11 interval 10

For information about BERT patterns, see References.

bert

• Use to enable bit error rate tests using the specified pattern on a 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 2^11 interval 10

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

Enabling Local, Network, and Payload Loopback

To enable local, network, or payload loopback testing of a T3 or E3 line, use the clock source and loopback commands from Controller Configuration mode.

1. Change the clock source to internal.

host1(config-controll)#clock source internal module

2. Specify a loopback.

host1(config-controll)#loopback local

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.

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.