8.1 Performing a Loopback on an E1 Line
The E1 line loopback is also called the 2M link physical loopback. When the services carried
on an E1 port are abnormal, you can perform a loopback on the E1 line to check whether the E1
port is normal and whether the internal communication of the system is normal.
Prerequisites
The services carried on the E1 port must run normally before a fault occurs. That is, the tested
loop must carry service streams.
Tools, Meters, and Materials
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E1 self-loop line (When an accurate test for the signal quality is not required, use the E1
self-loop line to perform the loopback on the E1 line.)
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Bit error meter (When an accurate test for the signal quality is required, use the bit error
meter to perform the loopback on the E1 line.)
Impact on the System
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Performing a loopback on the E1 line requires the disconnection of the E1 line. In this case,
all the services carried on the E1 port are interrupted. Therefore, perform the loopback
when the E1 line carries the minimum traffic.
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After the loopback is performed on the E1 line, the broadcast storm may occur if the E1
port is not isolated. Therefore, it is recommended that you cancel the loopback in time after
the loopback test is complete.
Precautions
None
Procedure
Step 1
Connect the transmit and receive ends of the tested E1 line to the E1 self-loop line or the
corresponding ports on the bit error meter, and ensure that they are in good contact.
Step 2
Verify the loopback result.
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When you use the E1 self-loop line to perform the loopback, run the
display port state
command to query the status of the port involved in the loopback. If the port is in the normal
state, it indicates that the E1 port works in the normal state and the internal communication
of the system is also normal.
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When you use the bit error meter to perform the loopback, you can determine whether the
E1 port and the internal communication of the system are normal through the indication
(whether there is a signal stream or not) on the bit error meter. In addition, you can determine
the signal quality of the line according to the indication on the bit error meter.
----End
SmartAX MA5612 Multi-service Access Module
Maintenance Guide
8 Common Operation
Issue 01 (2012-07-25)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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