Configure a Local Loopback

Purpose

Because ATM interfaces can be either SONET or T3, you use the sonet-options or t3-options statements to configure a local loopback. Figure 9 illustrates a local loopback configured for an ATM interface.

Figure 9: Local Loopback

Action

To configure a local loopback without physically connecting the transmit port to the receive port, follow these steps:

1. In configuration mode, go to the following hierarchy level:

[edit]

user@host# edit interfaces interface-name (sonet-options | t3-options)

2. Configure the loopback:

[edit interfaces interface-name (sonet-options | t3-options)]

user@host# set loopback local

3. Verify the configuration:

user@host# show

For example:

[edit interfaces (t3-1/0/0 t3-options)]

user@host# show

loopback local;

4. Commit the change:

user@host# commit 

For example:

[edit interfaces t3-1/0/0 t3-options]

user@host# commit 

commit complete

What It Means

When you create a local loopback, you create an internal loop on the interface being tested. A local loopback loops the traffic internally on that PIC. A local loopback tests the interconnection of the PIC but does not test the transmit and receive ports.

NOTE: Remember to delete the loopback statement after completing the test.