Clock Associated Parameters (TDM Mode)

6/13/2014 Clock Associated Parameters (TDM Mode)

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Clock Associated Parameters (TDM Mode)

Contents

1 Clock Associated Parameters (TDM Mode)

1.1 Clock Source Priority Sequence (1 Is the Highest)

1.2 Protection Status

1.3 AIS Alarm Generated

1.4 B1 BER Threshold-Crossing Generated

1.5 B2-EXC Alarm Generated

1.6 Higher Priority Clock Source Reversion Mode

1.7 Clock Source WTR Time(min)

1.8 Switching Status (Clock)

1.9 Lock Status

1.10 Clock Source ID

1.11 Synchronous Source

1.12 S1 Byte Synchronization Quality Information

1.13 NE Clock Working Mode

1.14 Clock Source Quality

1.15 S1 Byte Received

1.16 Line Port (Clock)

1.17 Control Status (Clock)

1.18 Line Port (Clock ID)

1.19 Enabled Status (Clock ID)

1.20 Data Output Method in Holdover Mode

1.21 Manual Setting of 0 Quality Level

1.22 Retiming Mode

1 Clock Associated Parameters (TDM Mode)

To synchronize the clocks on a network, you need to set the parameters that are associated with clocks.

Clock Source Priority Sequence (1 Is the Highest)

Protection Status



AIS Alarm Generated

B1 BER Threshold-Crossing Generated

B2-EXC Alarm Generated

Higher Priority Clock Source Reversion Mode

Clock Source WTR Time(min)

Switching Status (Clock)

Lock Status

Clock Source ID

Synchronous Source

S1 Byte Synchronization Quality Information

NE Clock Working Mode

Clock Source Quality

S1 Byte Received

Line Port (Clock)

Control Status (Clock)

Line Port (Clock ID)

Enabled Status (Clock ID)

Data Output Method in Holdover Mode

Manual Setting of 0 Quality Level

Retiming Mode

Parent topic: List of Parameters

1.1 Clock Source Priority Sequence (1 Is the Highest)

Description

The Clock source priority sequence(1 is the highest) parameter specifies the priority level of a certain clock source in the system clock priority table.

Impact on the System



When the SSM protocol is disabled or the extended SSM protocol is enabled, the current trace clock source may be changed if the clock source

priority sequence is changed. As a result, bit errors may occur in the service or the service may be interrupted transiently.

Values

Value Range Default Value

1, 2, 3... 1

The following table lists the description of each value.

Value Description

1 Indicates that this clock source is at the highest priority level in the system clock priority table.

2 Indicates that this clock source is at the second highest priority level in the system clock priority

table.

3 Indicates that this clock source is at the third highest priority level in the system clock priority table.

... ...

Configuration Guidelines

This parameter specifies the priority level of a certain clock source in the system clock priority table. The value ranges from 1 to N. N represents the

total number of clock sources in the system clock priority table. Generally, the internal clock source is at the lowest priority level.

For example, there are four clock sources in the system clock priority table: one external clock source, one line clock source, one tributary clock

source, and one internal clock source. The priority level of the external clock source is set to 1, the priority level of the line clock source is set to 2, the

priority level of the tributary clock source is set to 3 (the priority levels of the external clock source, line clock source, and tributary clock source cannot

be the same), and the priority level of the internal clock source is always set to 4.

In the actual application, this parameter is set according to the specific networking situation.

Parent topic: Clock Associated Parameters (TDM Mode)

1.2 Protection Status

Description



The Protection Status parameter indicates the working mode of the clock protocol for a clock subnet.


The algorithm adopted by the system to select a clock source varies with the parameter value.

Values


Start Extended SSM Protocol, Start Standard SSM Protocol, Stop SSM Protocol Stop SSM Protocol


The protection status of the entire clock subnet should be consistent. To avoid a clock tracing loop on a ring or mesh network, it is recommended that

you set this parameter to Start Extended SSM Protocol.

Relationship with Other Parameters

None.

Related Information

As a mechanism adopted by the synchronous network for synchronization management, the standard SSM protocol is loaded in the lower four bits of

the S1 byte. The standard SSM protocol allows nodes to exchange the quality information of clock sources. Hence, the SSM protocol enables the

system to automatically select the clock source with the highest priority and also avoids a clock inter-lock. The standard SSM protocol is applicable to

interconnection with the equipment of other suppliers.

Based on the standard SSM protocol, the extended SSM protocol presents a concept of clock source ID. The higher four bits of the S1 byte indicate a

unique clock source ID, which is transmitted with the SSM. When receiving the S1 byte, a node checks the clock source ID to see whether the clock

source derives from itself. If the clock source derives from the node, the node considers the clock source as unavailable. In this manner, a clock inter-

lock loop is avoided when the clock tracing path is configured as a ring. The extended SSM protocol is applicable to the interconnection of transmission

equipment from Huawei.

When the SSM protocol is disabled, the clock source is selected according to the priority table.


1.3 AIS Alarm Generated

Description



The AIS Alarm Generated parameter is used to specify whether an AIS alarm is a condition for triggering the switching of clock sources.


The system running is not affected.

Values


Yes, No No


Value Description

Yes Indicates that an AIS alarm is the sufficient condition to trigger clock source switching.

No Indicates that an AIS alarm is not a condition for triggering clock source switching.


It is recommended to set the AIS alarm as the condition for triggering clock source switching in actual application to ensure system performance.


None.

Related Information

None.


1.4 B1 BER Threshold-Crossing Generated

Description

The B1 BER Threshold-Crossing Generated parameter is used to specify whether a B1 BER threshold-crossing alarm is a condition for triggering

clock source switching. B1 BER Threshold-Crossing alarm is an index for measuring the performance of clock source signals.





Values


Yes, No No


Value Description

Yes Indicates that a B1 BER threshold-crossing alarm is the sufficient condition for triggering clock source switching.

No Indicates that a B1 BER threshold-crossing alarm is not the condition for triggering clock source switching.


A B1 BER threshold-crossing alarm indicates that the transmitted signal and the clock in the signal are being interfered. Therefore, this parameter can

be set as a condition for triggering clock source switching in actual application to ensure system performance.


None.

Related Information

None.


1.5 B2-EXC Alarm Generated

Description

The B2-EXC Alarm Generated parameter is used to specify whether a B2-EXC alarm is a condition for triggering clock source switching. B2-EXC alarm

is an index for measuring the performance of clock source signals.





Values


Yes, No No


Value Description

Yes Indicates that a B2-EXC alarm is the sufficient condition for triggering clock source switching.

No Indicates that a B2-EXC alarm is not the condition for triggering clock source switching.


A B2-EXC alarm indicates that the transmitted signal and the clock in the signal are being interfered. Therefore, this parameter can be set as a condition

for triggering clock source switching in actual application to ensure system performance.


None.

Related Information

None.


1.6 Higher Priority Clock Source Reversion Mode

Description

The Higher Priority Clock Source Reversion Mode parameter specifies whether to switch from the lower-priority clock source back to the higher-

priority clock source after the higher-priority clock source is restored to normal.




If the conditions for clock source switching are excessively strict, jitters may occur in the monitoring results of the clock status. If the auto-revertive

mode is selected, the frequent switching of clock sources may affect the service.

Values


Non-Revertive, Auto-Revertive Auto-Revertive


Value Description

Non-Revertive Indicates that the higher-priority clock source cannot be selected automatically after it is restored to normal.

Auto-Revertive Indicates that the higher-priority clock source is selected automatically after it is restored to normal.


If the conditions for clock source switching are properly set and the switching of clock sources can be guaranteed, the Auto-Revertive mode can be

selected to improve clock quality. Otherwise, the Non-Revertive mode is recommended to avoid clock jitters.


None.

Related Information

None.


1.7 Clock Source WTR Time(min)

Description

The Clock Source WTR Time(min) parameter is used to specify the wait-to-restore (WTR) time when the Higher Priority Clock Source Reversion

Mode parameter is set to Auto-Revertive. When a clock source is restored to its valid status, the system does not regard it as a valid source



immediately but verifies the validity of the clock source in a specific period of time. The system regards the clock source as a valid source only if the

clock source remains valid during the specific period of time. This specific period of time is called the WTR time of the clock source.


Insufficient WTR time may result in wrong judgments on clock source restoration and clock status jitters, which may interrupt the service.

Values


0-12 5


The WRT time is counted in minutes. The shorter the WTR time is, the faster the clock is recovered, and the higher the average clock quality is. On the

other hand, the shorter the WTR time is, the more likely the clock jitters are caused due to unstable clock signals. Therefore, do not set the WTR time

to 0 in actual application.


The setting of the WTR time is valid only when the Higher Priority Clock Source Reversion Mode parameter is set to Auto-Revertive.

Related Information

None.


1.8 Switching Status (Clock)

Description

The Switching Status (Clock) parameter indicates the current switching status of a clock source in the clock priority table.



Values




Normal, Forced Switching, Manual Switching Normal


Value Description

Normal Indicates that the clock source in the clock priority table is in the normal trace status.

Forced Switching Indicates that the clock source in the clock priority table is in the forced switching status.

Manual Switching Indicates that the clock source in the clock priority table is in the manual switching status.


None.


None.

Related Information

None.


1.9 Lock Status

Description

The Lock Status parameter indicates the lock status of a clock source in the priority table.



Values




Lock, Unlock Unlock


Value Description

Lock Indicates that a certain channel of clock source in the priority table is in the lock status where the switching of clock sources is not allowed.

Unlock Indicates that a certain channel of clock source in the priority table is in the unlock status where the switching of clock sources is allowed.


None.


None.

Related Information

None.


1.10 Clock Source ID

Description

The Clock Source ID parameter specifies the clock source ID information that is transmitted in the four most significant bits of the overhead S1 byte to

avoid timing loops. This parameter works in the extended SSM protocol mode.



Values




1-15, None None


In actual application where the extended SSM protocol is enabled, the clock source IDs should be set as required by network planning to ensure that

the ID is networkwide unique.


This parameter is valid only when the extended SSM protocol is enabled.

Related Information

None.


1.11 Synchronous Source

Description

The Synchronous Source parameter indicates the synchronous clock source that is being traced. The synchronous clock source here refers to a

certain clock source contained in the system clock priority table.



Values


Clock Source in System Clock Priority Table None


Value Description

Clock Source in System Clock

Priority Table

Indicates that the system clock priority table contains the tributary clock sources, line clock sources, external

clock sources, and internal clock sources.




The OptiX OSN 550 does not support External Clock Source.


None.

Related Information

None.


1.12 S1 Byte Synchronization Quality Information

Description

The S1 Byte Synchronization Quality Information parameter indicates the synchronization quality information in the S1 byte that is output by the

current traced synchronous source. The S1 byte defined by the ITUT is used to transmit the quality information about the clock sources. It indicates the

quality information of 16 types of synchronous sources with bits 5-8 of the S1 byte in the section overhead. With this quality information and certain

switching protocols, the automatic protection switching of the synchronization clock can be realized in the synchronous network.



Values

Value Range Default

Value

Synchronous Source Unavailable, Quality Unknown, G.811 Reference Clock, G.812 Transit Clock, G.812 Local Clock, SDH equipment

timing source (SETS) signal

-


Value Description



Synchronous Source

Unavailable

Indicates that the SSM protocol is disabled and the S1 byte synchronization quality information output by the

synchronous source is not available.

Quality Unknown Indicates that the SSM protocol is started but the S1 byte synchronization quality information output by the synchronous

source is unknown.

G.811 Reference Clock Indicates that the SSM protocol is started and the S1 byte synchronization quality information output by the

synchronous source is the G.811 reference clock.

G.812 Transit Clock Indicates that the SSM protocol is started and the S1 byte synchronization quality information output by the

synchronous source is the G.812 transit clock.

G.812 Local Clock Indicates that the SSM protocol is started and the S1 byte synchronization quality information output by the

synchronous source is the G.812 local clock.

SDH equipment timing

source (SETS) signal

Indicates that the SSM protocol is enabled and the S1 byte synchronization quality information output by the

synchronous source is the synchronous equipment timing source (SETS) clock.


None.


None.

Related Information

None.


1.13 NE Clock Working Mode

Description

The NE Clock Working Mode parameter is used to set the current working mode of the system clock to the normal, holdover or free-run mode.





Values


Normal Mode, Holdover Mode, Free-Run Mode -


Value Description

Normal

Mode

Indicates that the NE clock works in the tracing mode. That is, the NE clock traces and locks the working mode of its upper-level clock.

Holdover

Mode

Indicates that the NE clock works in the holdover mode. That is, in this mode, the NE clock uses the frequency information that is stored

before all timing reference signals are lost as its timing reference.

Free-Run

Mode

Indicates that the NE clock works in the free-run mode. That is, the internal oscillator works in this mode when all external timing reference

signals are lost.


None.


None.

Related Information

None.


1.14 Clock Source Quality

Description

The Clock Source Quality parameter specifies the clock source quality information. Such information is extracted from the S1 byte of individual clock

sources according to the SSM encoding rules after the SSM protocol is enabled. If the clock quality information cannot be extracted, this parameter

needs to be set manually.





Values


Automatic Extraction, G.811 Clock Signal, G.812 Transit Clock Signal, G.812 Local Clock Signal, G.813 SDH Equipment Timing

source (SETS) Signal, Unknown Synchronization Quality

Automatic

Extraction


Value Description

Automatic Extraction Indicates that the clock quality information is extracted automatically according to the encoding rules

compliant with the SSM protocol.

G.811 Clock Signal Indicates that the clock source quality is manually set to the G.811 clock signal.

G.812 Transit Clock Signal Indicates that the clock source quality is manually set to the G.812 transit clock signal.

G.812 Local Clock Signal Indicates that the clock source quality is manually set to the G.812 local clock signal.

G.813 SDH Equipment Timing source

(SETS) Signal

Indicates that the clock source quality is manually set to the SETS clock signal.

Unknown Synchronization Quality Indicates a message that is set in the negative direction of the selected synchronization source to avoid direct

mutual locking of two adjacent NEs.


This parameter is usually set to Automatic Extraction. When the equipment is interconnected to an NE from another manufacturer that complies with

a different protocol, the clock source quality can be specified manually.


The clock quality information is valid only when the SSM protocol is enabled.

Related Information



None.


1.15 S1 Byte Received

Description

The S1 Byte Received parameter indicates the value of the S1 byte of the current traced source in the system clock priority table.



Values


SDH equipment timing source (SETS) signal, G.812 Local Clock, G.812 Transit Clock, G.811 Reference Clock,

Synchronous Source Unavailable

Synchronous Source

Unavailable


Value Description

SDH equipment timing source (SETS) signal Indicates that the clock quality of the current traced source is 0x0b.

G.812 Local Clock Indicates that the clock quality of the current traced source is 0x08.

G.812 Transit Clock Indicates that the clock quality of the current traced source is 0x04.

G.811 Reference Clock Indicates that the clock quality of the current traced source is 0x02.

Synchronous Source Unavailable Indicates that the clock quality of the current traced source is 0x0f.


None.




None.

Related Information

None.


1.16 Line Port (Clock)

Description

The Line Port (Clock) parameter is used to specify the output port of SSM quality information about the line clock source and external clock source

available in the existing system. This output port can transmit the quality information about the clock source by sending the S1 byte to the downstream

NE.



Values


Line Clock Source Port, External Clock Source Port -


Value Description

Line Clock

Source Port

Indicates that only the port on the line board where both physical board and logical board have been configured properly can be

used as the output port of SSM quality information.

External Clock

Source Port

Indicates that only the port on the board with external clock interfaces where both physical board and logical board have been

configured properly can be used as the output port of SSM quality information.


None.




None.

Related Information

The standard SSM protocol mode, also called as QL_ENABLE mode in the Recommendation G.781, is a universal switching mode of clock source. In

this standard SSM protocol mode, when a clock source becomes invalid, the system automatically traces the clock source of the highest quality in the

clock priority table according to the quality information contained in the SSM protocol. If two clock sources are both of the highest quality, the clock

source of a higher priority is selected.


1.17 Control Status (Clock)

Description

The Control Status (Clock) parameter is used to specify whether the line port can transmit the quality information about the clock source by sending

the S1 byte to the downstream NE. By setting this parameter, the transmission of the S1 byte through the ports of the clock source can be enabled or

disabled.


Modifying the Control Status (Clock) parameter may cause loss of clock quality information transmitted to the downstream NE. Therefore, the clock of

the downstream NE may be asynchronous with the clocks of other NEs in the synchronous network.

Values


Enable, Disabled Enable


Value Description

Enable Indicates that the transmission of the S1 byte through the corresponding line port is enabled.

Disabled Indicates that the transmission of the S1 byte through the corresponding line port is disabled.




The Control Status (Clock) parameter can be set to an enabled or disabled status as required. The status is enabled by default. In actual application, if

the output clock source on the line board is valid, the transmission of the S1 byte through line port is allowed so that the clocks of the NEs in the entire

synchronous network are synchronous.


None.

Related Information

The standard SSM protocol mode, also called QL_ENABLE mode in the G.781, is a universal switching mode of the clock source. In this standard SSM

protocol mode, when a clock source becomes invalid, the system automatically traces the clock source of the highest quality in the clock priority table

according to the quality information contained in the SSM protocol. If two clock sources are both of the highest quality, the clock source of a higher

priority is selected.


1.18 Line Port (Clock ID)

Description

The Line Port (Clock ID) parameter is used to set clock source ID in the S1 byte for the interconnection and isolation between different clock subnets.

In the extended SSM protocol mode, the four most significant bits of the S1 byte are used for identifying the clock source ID to improve the clock

protection performance in the SDH network and to effectively avoid the timing loop. The clock source ID is output by the line port only. The external

clock cannot output the clock source ID.



Values


Line Clock Source Port -




Value Description

Line Clock

Source Port

Indicates that only the port on the line board where both physical board and logical board have been configured properly can be

used as the output port of the clock source ID.


None.


None.

Related Information

None.


1.19 Enabled Status (Clock ID)

Description

Then Enabled Status (Clock ID) parameter is used to enable or disable the output of the clock source ID for the interconnection and isolation between

different subnets. In the extended SSM protocol mode, the four most significant bits of the S1 byte are used for identifying the clock source ID to

improve the clock protection performance in the SDH network and to effectively avoid the timing loop. This parameter is used to enable or disable the

output of the clock source ID. The output of the clock source ID by internal clock source cannot be disabled. This parameter cannot be set for external

clock, because the external clock cannot output the clock source ID.


In a system where the extended SSM protocol is adopted, modifying the Enable Status (Clock ID) parameter may result in clock tracing loop, which

may make the originally synchronous clock sources asynchronous.

Values


Enabled, Disabled Enabled




Value Description

Enabled Indicates that the output of clock source ID through corresponding line ports is allowed.

Disabled. Indicates that the output of clock source ID through corresponding line ports is forbidden.


The Enabled Status (Clock ID) parameter can be set to an enable of disabled status as required. The status is enabled by default. In actual

application, as long as the extended SSM protocol is started and the output clock source on the line board is valid, it is allowed to output clock source

ID in the four most-significant bits of the S1 byte through line ports. This can ensure clock synchronization among the NEs in the entire synchronous

network and prevent the occurrence of timing loops.


There are three working modes of the SSM protocol: the disabled, standard and extended SSM protocol modes. This parameter is valid only when the

extended SSM protocol mode is adopted by the current clock of the NEs.

Related Information

None.


1.20 Data Output Method in Holdover Mode

Description

The Data Output Method in Holdover Mode parameter is used to specify whether the data is output normally or the latest data is kept when the NE

clock is in the holdover mode.



Values




Normal Data Output Mode, Keep the Latest Data Normal Data Output Mode


Value Description

Normal Data

Output Mode

Indicates the normal data output mode. The duration of this output mode is determined by the phase lock. This data output mode

can continue for a maximum of 24 hours.

Keep the Latest

Data

Indicates that the latest phase-locked data is kept. This data output mode is a forced holdover mode.


The Keep the Latest Data mode is a forced holdover mode. Therefore, the clock accuracy is not high. In actual application, the Normal Data Output

mode is recommended.


The NE clock can work in three modes: the trace, holdover, and free-run modes. This parameter is valid only when the NE clock is working in the

holdover mode.

Related Information

None.


1.21 Manual Setting of 0 Quality Level

Description

The Manual Setting of 0 Quality Level parameter is used to specify the 0 quality level that is not provided in the SSM protocol. Users can add this

parsing rule to specify the quality level represented by 0.



Values




Do Not Use For Synchronization, G.811 Reference Clock, G.812 Transit Clock, G.812 Local Clock, SETS Clock, Between G.811

Reference Clock and G.812 Transit Clock, Between G.812 Transit Clock and G.812 Local Clock, Between G.812 Local Clock and

synchronous equipment timing source (SETS)

Do Not Use For

Synchronization


Value Description

Do Not Use For Synchronization Indicates a message that is set in the negative direction of the selected synchronization source to avoid

direct mutual locking of two adjacent NEs.

G.811 Reference Clock Indicates that the clock signal complies with the G.811 protocol.

G.812 Transit Clock Indicates that the transit exchange clock signal complies with the G.812 protocol.

G.812 Local Clock Indicates that the local office signal complies with the G.812 protocol.

SETS Clock Indicates the synchronous equipment timing source (SETS).

Between G.811 Reference Clock and

G.812 Transit Clock

Indicates that the specified quality level is inferior to the quality level of the G.811 reference clock signal

but is superior to the quality level of the G.812 transit clock signal.

Between G.812 Transit Clock and G.812

Local Clock

Indicates that the specified quality level is inferior to the quality level of the G.812 transit clock signal but is

superior to the quality level of the G.812 local clock signal.

Between G.812 Local Clock and

synchronous equipment timing source

(SETS)

Indicates that the specified quality level is inferior to the quality level of the G.812 local clock signal but is

superior to the quality level of the synchronous equipment timing source (SETS) clock signal.


In actual application, this parameter can be set according to the quality information about specific NE clocks.


The setting of this parameter is valid only when the SSM protocol is enabled.

Related Information



None.


1.22 Retiming Mode

Description

The Retiming Mode parameter specifies whether the retiming clock, tributary clock, or cross-connect (external) clock is used.


If the downstream board that corresponds to this board provides the clock source for the downstream NE, the selection of the user affects the precision

of the downstream NE.

Values


Normal, Retiming Mode of Tributary Clock, Retiming Mode of Cross-Connect Clock Normal

The following table provides the description of each value.

Value Description

Normal Indicates that the retiming clock is not used.

Retiming Mode of Tributary Clock Indicates that the tributary clock is used as the retiming clock.

Retiming Mode of Cross-Connect Clock Indicates that the cross-connect (external) clock is used as the retiming clock.


Select the proper clock according to the actual networking planning of the user.


Clock Associated Parameters (TDM Mode)

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