Testing Interfaces

If you want to run loopback tests or bit error rate tests on channelized T3 interfaces, you must enable testing at the T3 or T1 layer. See Interface Stack for a description of the layers.

For a list of the modules that support bit error rate tests (BERTs) and remote loopback, see ERX Module Guide, Appendix A, Module Protocol Support.

Note: BERTs are supported on frame-based channelized T3 interfaces, with the exception of the CT3/T3 line module used with the 3-port CT3/T3 I/O module.

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

equipment loopback

loopback

Testing at the T1 Layer

The T1 channel testing commands enable you to specify testing parameters for a single channel, multiple individual channels, ranges of channels, or any combination of the three types of specifications. For example:

host1(config-controll)#t1 3,6-15,22,25-27 loopback local

To enable testing at the T1 layer:

  1. Configure one of the following loopback tests.
    • Set the loopback to local to test the line without connecting to the network.
      host1(config-controll)#t1 2 loopback local
    • Set the loopback to network to test the line connected to the network.
      host1(config-controll)#t1 2 loopback network line
    • Set the loopback to remote-loopback to enable acceptance of loopback commands issued from a remote router.
      host1(config-controll)#t1 2 remote-loopback
  2. Configure the line to run bit error rate tests.
    host1(config-controll)#t1 2 bert pattern 2^11 time 10 unframed

t1 bert

t1 loopback

t1 remote-loopback