Priorities - Alcatel-Lucent 1643 AMS User's Operation Manual

Timing provisioning

Priorities

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Introduction
The timing reference signal is transported through a synchronized network by the
network elements. The path this timing signal will follow can be controlled by the
network operator.
Description
When only the quality level of the timing reference signal is used, more signals with
equal quality level can arrive at a network element. To determine the timing source
that the network element will choose in such a case, a priority is assigned to each
timing source.
In choosing a timing source, the network element first selects the timing source with
the highest quality level. When there are several timing sources available with this
highest quality level, the priority is taken into account.
Example
In this figure, notice how the priorities define the timing path when each node receives
two signals of PRC quality. The priority in the upper node is disabled since this input
signal depends on an output signal of this network element; this could cause a timing
loop, as explained in "Timing Loop".
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7-10 Alcatel-Lucent - Proprietary
See notice on first page
365-312-807R7.2
Issue 4, May 2007