Use N2 to turn Near End loopback on or off for port 2.

The Near End loop is also called a DTE loop, it is a loopback test that takes place in the DIU and is bidirectional. On the DIU the Near End Loop LED will come on for the port which is in loopback.

If the customer equipment is capable of reporting a loopback, as most routers and time division multiplexers are, it should indicate a loopback exists while the Near End loopback is on. This would verify the local DTE to DIU port cabling.

If the customer equipment at the far end location reports a loopback during a Near End Loop at the local site, and no test is in progress at the Far End site; this would indicate that the far end CSU/DSU, the T1 circuit and the local CSU/DSU all have continuity at least (if not error free).