Looping Back the Interface Board Port Timeslot

This describes how to query the mode, status, and remaining time of the timeslot loopback, and how to start or stop the timeslot loopback on the basis of the query result.

Prerequisites

The LMT runs normally.
The communication between the LMT and the BSC is normal.
All the interface boards are functional.

Context

Timeslot loopback is used to loop back the data carried by the timeslot. You can determine the loopback direction by selecting a loopback mode. Through the timeslot loopback, you can determine whether the transmission on a speech channel is normal or not.
Timeslot loopback is of two modes: remote loopback and local loopback.
- Remote Loopback: The signals received on a timeslot are sent out without being processed.
- Local Loopback: The signals that should be placed in the sending direction are placed in the receiving direction as the received data.
Different interfaces use different timeslots. The A interface uses 64 kbit/s timeslots. The Pb interface uses 16 kbit/s timeslots. The Abis interface uses 8 kbit/s or 6 kbit/s timeslots. The Ater interface uses 16 kbit/s timeslots.
In the case of the loopback in the unit of 64K, other users in the same unit of 64K may be affected.
When the timeslot loopback of the Abis/Ater interface board is performed, the timeslot of the loopback needs to be set properly. The E1 timeslot (setting to X) can be calculated through the timeslot queried in the function of querying the single user calling resources. The calculation method is: X = Y/8.

Procedure

Through GUI
1. On the LMT, choose BSC Maintenance > Maintain Transmission and Signaling > Interface Board Port Timeslot Loopback. The Interface Board Port Timeslot Loopback dialog box is displayed.
2. As shown in Figure 1, set parameters in the Timeslot Location area, and then click Query. The query results are displayed, as shown in Figure 1.
  Figure 1 Query result
3. Set Loopback Mode and select query results.
  - Select one or several check boxes in the list.
  - Double-click the list to select all the query results.
4. Click Start. A dialog box is displayed.
5. Click Yes. The results are displayed, as shown in Figure 2.
  Figure 2 Starting the timeslot loopback
  
  NOTE:
  You cannot start loopback for the port timeslot that is already in loopback state or whose status fails to be queried.
6. Click Stop to end the timeslot loopback.
Through MML
1. You can run the following commands on the Local Maintenance Terminal to loop the interface board timeslots.
  - Run the DSP E1T1TS command to query the loop attributes of electrical interface ports.
  - Run the DSP OPTTS command to query the loop attributes of electrical interface ports.
  - Run the SET E1T1LOP command to set the loop mode of the electrical interface board port timeslots.
  - Run the SET OPTLOP command to set the loop mode of the optical interface board port timeslots.
  - Run the SET OPTSUBBRDLOP command to set the loop mode of the sub-boards of optical interface board port timeslots.