Classification Of Clock Sources; Reference Source Level - H3C S9500 Series Operation Manual

Operation Manual – Clock Monitoring
H3C S9500 Series Routing Switches
S9502 S9502
S9505 S9505
S9508 S9508
S9512 S9512
Figure 1-1 Relationship between reference source and slot

1.1.2 Classification of Clock Sources

Clock sources can be classified into three categories according to different sources of
the clock source of the clock monitoring module:
Local clock source: 38.88 MHz clock signals generated by a crystal oscillator
inside the clock monitoring module.
Bits clock source: clock signals generated by a Bits clock device. The signals are
sent to the clock monitoring module through a specific interface on the SRPU
(switch and router processing unit) and then sent to all interface cards by the clock
monitoring module.
Line clock source: clock signals provided by the upper level device. Its precision is
lower than Bits clock source. The signals are derived from the specific WAN
interface and then sent to the clock monitoring module, which sends the signals to
all interface cards in turn.

1.1.3 Reference Source Level

The reference source level is decided together by the priority and the synchronization
status marker (SSM) level of the reference source.
I. Priority of the reference source
You can set a high priority for the reference source with high-precision and
high-reliability to make it be selected as the clock source with precedence.
II. SSM level of the reference source
SSM, also known as synchronization quality marker, is used to indicate the
synchronization timing signal level on a synchronization timing transmission link.
The priority of SSM level of the reference source, ranging from high to low includes:
PRC: G.811 clock signal
TNC: G.812 transit node clock signal
LNC: G.812 local node clock signal
SETS: SDH device clock source signal
unknown: Unknown synchronization quality
Chapter 1 Clock Monitoring Configuration
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