Hello, everyone!
Although the E1 service can provide only a 2.048 Mbit/s channel rate and is almost obsolete in carrier networks, it is still widely used in enterprise networks. This article will share some tips on how to test the availability of E1 services.
In actual transport networks, the network topology is complex. The following figure shows the signal flow of E1 services in point-to-point topology mode：
Note that the preceding figure shows the E1 services provided by the SDH+PDH boards. In actual applications, the E1 channels can also be provided by packet boards configured with CES services.
As long as we understand the signal flow, it is easier for us to check the performance of the E1 channel.
Mode 1: check it by NMS alarm
1. Loop back signals on the DDF at both ends of the E1 path.
2. In the NE Panel, right-click an EI service processing board (such as PQ1) and choose Browse SDH Trails from the shortcut menu.
3. In the Manage SDH Trail window, if the alarm status of an EI trail is No alarm, the performance of the E1 channel is normal.
Method 2: check it by PRBS test
1. Double-click the EI service processing board (for example, PQ1) in the peer NE panel. In the Path-View-NE window, right-click the corresponding PPI module and choose Tributary Loopback > Inloop.
2. In the dialog box that is displayed, click Yes. The loopback icon is displayed on the board and the corresponding channel module.
3. In the NE Explorer, select the PQ1 board and choose Configuration > PRBS Test from the Function Tree. Select the E1 channel to be tested and set parameters to perform a PRBS test.
If the axis diagram displays a green bar chart, it indicates that the equipment works normally. If the axis diagram displays a yellow bar chart, it indicates that the transmission line is interrupted and completely fails. If the axis diagram displays a red bar chart, it indicates that bit errors exist on the transmission line. For details, click Performing a PRBS Test
Mode 3: check it by instrument test
The BER tester or SDH analyzer can be used.
Online test
1. Connect the receive port of the E1 tester to the test port of the Y-shaped port, as shown in the following figure.
2. Perform an online test on the E1 tester. If the tester displays an out-of-frame alarm, (LOF: Generally, the meter does not match the signals sent by the customer equipment. Therefore, the LOF alarm is generated.) The E1 link is normal. If the meter displays other alarms, such as bit error alarms, the E1 link is abnormal.
Offline test
The method of using the meter is simple. That is, perform a loopback on the DDF at one end of the path, and then use the E1 BER tester to perform the test at the other end.
Note that the preceding figure shows the E1 services provided by the SDH+PDH boards. In actual applications, the E1 channels can also be provided by packet boards configured with CES services.
The test period is usually 15 minutes or 24 hours. If no errored second is generated, the EI channel is of good quality.
Summary
1. Services are not interrupted only when the meter is used to perform the online test.
2. The first and second methods can be performed only on the NMS.
3. The third and first methods need to be performed onsite. However, they can test whether the line between the SDH equipment and the DDF is normal. Therefore, the coverage is wider.That's all, welcome everyone to leave a message and exchange in the comment area!
Thank you！
Extended information:
How to test the availability of Ethernet services
