SEC
An SDH network element has its own internal oscillator, called the SDH equipment
clock (SEC). The accuracy of a SEC is lower than the accuracy of both the SSU and
the PRC.
Network example
The next figure gives an example of a network. Four network elements (NEs) of a
large network are drawn, plus a master clock (PRC) and a SSU.
SDH
Network
SDH
Network
Working Synchronization
Stand-by Synchronization
SSU
NE
NE
NE
NE PRC
Line A
Line A
Line A
Line A
Line B
Line B
Line B
Line B
Station clock
input
Station clock
input
Station clock
output
Master
Clock
Timing provisioning
Network synchronization
....................................................................................................................................................................................................................................
7-8
Alcatel-Lucent - Proprietary
See notice on first page
365-312-807R7.2
Issue 4, May 2007
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