Step 1: Create a Loopback
Purpose
You can create a physical loopback or configure a local loopback to help diagnose a suspected hardware problem. Creating a physical loopback is recommended because it allows you to test and verify the Channelized OC-12 or Channelized OC-12 IQ port. If a field engineer is not available to create the physical loopback, you can configure a local loopback for the interface. The local loopback creates a loopback internally in the Physical Interface Card (PIC).
NOTE: For a list of interface types associated with the Channelized OC-12 IQ interface, see Channelized Intelligent Queuing Interface Naming.