Raisecom Technology Co., Ltd
13
OPCOM3100-155 can organize ring topology network at STM-1speed with
flexible service configuration and high reliability, it also can realize 2F
SNC-P function.
E1 electrical
signal/Ethernet
signal
STM-1 ring
ADM
ADM
ADM
ADM
E1 electrical
signal/Ethernet
signal
E1 electrical signal/Ethernet signal
E1 electrical signal/Ethernet signal
Figure 5-5 ring topology
5.3. Clock
Clock of OPCOM3100-155 is compliant with G.813 standard.
1
．
Clock
mode
●
Locking: clock is locked with outside input clock signal.
●
Holding: clock module will work at the last input signal frequency when
the input clock signal reference is lost.
●
Free running: clock module will work at the inside oscillator frequency.
2
．
Clock source select
The clock mode of OPCOM3100 is related to master/slave station. Master
station uses free running mode and slave station uses recovered clock. For
slave station, there are two recovered clock references: the first optical line
(primary reference clock) and the second optical line (standby reference
clock). OPCOM3100 will switch the reference clock from the first optical line to
the second if the primary reference clock is not available (including there is
LOS and the frequency offset is more than 4.6ppm), and if the primary
reference clock has recovered it will switch back.
3
．
Clock source switching
There won’t be error code and too much jitter if OPCOM3100 is forced to
switch from master station to slave station or from slave station to master
