Switching Of Reference Clock - Zte ZXA10 S300 Technical Manual

ZXA10 S300 (V1.1) Integrated Access Service Dispatching Unit Technical Manual
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Recover timing from the signals of other tributaries like the
POS optical interface.

Switching of Reference Clock

The time for triggering the timing switching is within 10 second
after the loss of timing reference signal is detected or after AIS
signals occur at the timing interface.
The timing reference can be recovered both automatically and
manually. If there is a valid timing signal, the timing reference
will be recovered automatically within 10 ∼ 20 seconds.
The ZXA10 S300 can identify the label of the timing signal in the
SOH of the STM-N frame structure. It also supports the SSM
switching. Recommendation G.707 defines the SSM in the S1
byte of the multiplex section in the STM-N frame structure. In
the S1 byte, the 16 codes in Bit 5 ∼ Bit 8 stand for different
information, and indicates the quality level of the clock. See
Table 23.
2 3 − S
T
A B L E Y N C H R O N I Z A T I O N
Bit 5 ∼ Bit 8 of the
Serial
No. SOHS1 Byte
0 0000
1 0001
2 0010
3 0011
4 0100
5 0101
6 0110
7 0111
8 1000
9 1001
10 1010
11 1011
12 1100
13 1101
14 1110
15 1111
Q S M
U A L I T Y T A T U S E S S A G E
Type of SDH Synchronization
Quality Grade
Quality unknown (current
synchronization network)
Reserved
Reference clock (G.811)
Reserved
Enhanced Grade-2 clock (G.812)
Reserved
Reserved
Reserved
Enhanced Grade-3 clock (G.812)
Reserved
Reserved
SDH Equipment Clock (G.813)
Reserved
Reserved
Reserved
Not to be used for synchronization