Use F2 to turn Far End loopback on or off for port 2.
The Far End loop is also called a remote DTE loop, it is a loopback test that takes place in the DIU and is bidirectional. A loopup or loopdown code is sent from the near site to the far site through the T1. On the DIU at this site the Far End Loop LED will come on for the port which is in loopback. On the DIU at the far site the Near End Loop LED will come on for the port which is in loopback.