Chapter 6. Diagnostics6-2 MX2800 STS-1 User Manual 61200659L1-1VT/PORT LOOPBACKSAfter you select the number that corresponds with the line you wantto test, the menu in Figure 6-2 appears. The number selected(1-28) refers to the VT number. The Port (T1/E1) that will be testedis the port mapped to the selected VT number. The sectionsfollowing the figure provide descriptions and illustrations of thetesting options. Select 1-D ATA M ODE to end a test in progress.Figure 6-2. VT/Port Diagnostics MenuTributaryA T RIBUTARY loopback loops the selected VT/Port back to thenetwork (STS-1). The T1/E1 is looped back through the STS-1mapper. During this loopback, the corresponding DSX-1/E1 inputis overwritten by the outgoing DSX-1/E1 signal. See Figure 6-3 onpage 6-3 for an illustration of this test.
