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<h1>Trunk Network Maintenance</h1>

<p>Functional disturbances in the trunk network are inconvenient
to the customers using the network and cause financial losses to the operator.
Therefore, it is important that the exchange can adapt itself even to very
serious malfunctions of the trunk network and provide reliable service with
the available resources.  In addition, the system supports fault-preventive
and corrective operations.</p>


<p>The DX 200 system provides real time supervision of the
trunk network. The trunk network and the exchange terminals are the objects
of the supervision. If a disturbance occurs, the system isolates the faulty
connection from traffic until the connection is back in order. The maintenance
personnel are informed of the situation through the alarm system, and new
traffic is routed to the correctly working connections. The DX 200 system
is able to provide high-quality trunk service even in situations where the
disturbances are very serious.</p>


<p>In many cases, it is possible to predict the faults appearing
in a trunk circuit days in advance, based on an increasing number of short
disturbances. For this purpose, the system records daily statistics about
the disturbances and the availability characteristics of all trunk circuits.</p>


<p>To support repair work, short measurements on disturbance
characteristics found in the trunk circuits are performed. The measurements
are controlled with the MML commands.</p>
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