Alcatel-Lucent 1643 AMS - NE timing

NE timing
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Introduction
For telephone exchanges or switches, accurate timing is critical. Therefore switches are
synchronized with each other. One way of synchronizing is through the network. In
this case all the SDH-network elements in the network are synchronized with one
master clock. All the switches in the network can synchronize with the network, and
consequently to the master clock.
Timing reference
The timing signal received by a network element is called the timing reference.
The 1643 AM or 1643 AMS can work in two different mode, the STM-1 and the
STM-4 mode.
If it is working in the STM-1 mode, the different ports that provide the input signals
that are available as timing references are the:
• line port
• tributary port.
If the 1643 AM or 1643 AMS is working in the STM-4 mode and if the STM-1 option
board is available, an extra tributary port is present as a timing reference.
Timing output
A network element can provide a synchronization signal to other equipment by sending
an output timing signal.
Different output timing sources that can be used are:
• station clock output
• line port
• tributary port.
External clock output
For synchronization of equipment that is not connected to the network element by
tributary or line signals, the network element can provide an external clock signal
(usually two Mhz). However, this equipment must be in close proximity to the network
element as the clock signal can only be carried a few hundred meters.
Timing sources and outputs
A schematic drawing of a network element with the timing sources and output is
shown. The dotted arrows indicate outgoing timing signals. The straight arrows indicate
the timing inputs on which the internal clock of the network element can be
synchronized.
Timing provisioning
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7-4
Alcatel-Lucent - Proprietary
See notice on first page
365-312-807R7.2
Issue 4, May 2007