Example for Configuring Synchronous Ethernet

Networking Requirements

In Figure 1, devices on the clock synchronization network are connected to each other, forming a ring topology. To ensure reliability on the clock synchronization network, Device1 and Device3 each are connected to an external clock source to import clock signals. During network deployment, each device preferentially traces clock signals sent from Device1. When the clock source connected to Device1 is faulty, devices trace clock signals sent from Device3.

To ensure that devices can trace clock signals with the best quality, each device is configured with an SSM quality level that is used for clock source selection.

Figure 1 Ring networking of clock synchronization

In this example, interface1, interface2, and interface3 are XGigabitEthernet0/0/1, XGigabitEthernet0/0/2, and XGigabitEthernet0/0/3.

An example of the devices that support external clock interfaces is S12700.

**Table 1** Clock source priorities and SSM quality levels of different devices
Device	Current Clock Source	Priority	SSM Quality Level
Device1	XGigabitEthernet0/0/1	2	-
	XGigabitEthernet0/0/2	-	-
	XGigabitEthernet0/0/3	1	ssua
Device2	XGigabitEthernet0/0/1	1	-
Device2	XGigabitEthernet0/0/2	2	-
Device3	XGigabitEthernet0/0/1	-	-
	XGigabitEthernet0/0/2	3	-
	XGigabitEthernet0/0/3	1	ssub
Device4	XGigabitEthernet0/0/1	1	-
Device4	XGigabitEthernet0/0/2	2	-

Configuration Roadmap

The configuration roadmap is as follows:

Configure a clock source.
Configure automatic clock source selection and enable the use of SSM quality level to participate in clock source selection.
Simulate a fault of the external clock connected to Device1 to check clock switching of the devices.

Procedure

Configure a clock source.

# Configure Device1 to connect to the line clock source through Ethernet interfaces.

<HUAWEI> system-view
[HUAWEI] sysname Device1
[Device1] clock ethernet-synchronization enable
[Device1] interface XGigabitEthernet 0/0/1
[Device1-XGigabitEthernet0/0/1] clock synchronization enable
[Device1-XGigabitEthernet0/0/1] clock priority 2
[Device1-XGigabitEthernet0/0/1] quit
[Device1] interface XGigabitEthernet 0/0/2
[Device1-XGigabitEthernet0/0/2] clock synchronization enable
[Device1-XGigabitEthernet0/0/2] quit
[Device1] interface XGigabitEthernet 0/0/3
[Device1-XGigabitEthernet0/0/3] clock synchronization enable
[Device1-XGigabitEthernet0/0/3] clock ssm ssua
[Device1-XGigabitEthernet0/0/3] clock priority 1
[Device1-XGigabitEthernet0/0/3] quit

# Configure Device2 to connect to a line clock source through Ethernet interfaces. The configuration of Device4 is similar to the configuration of Device2, and is not mentioned here.

<HUAWEI> system-view
[HUAWEI] sysname Device2
[Device2] clock ethernet-synchronization enable
[Device2] interface XGigabitEthernet 0/0/1
[Device2-XGigabitEthernet0/0/1] clock synchronization enable
[Device2-XGigabitEthernet0/0/1] clock priority 1
[Device2-XGigabitEthernet0/0/1] quit
[Device2] interface XGigabitEthernet 0/0/2
[Device2-XGigabitEthernet0/0/2] clock synchronization enable
[Device2-XGigabitEthernet0/0/2] clock priority 2
[Device2-XGigabitEthernet0/0/2] quit

# Configure Device3.

<HUAWEI> system-view
[HUAWEI] sysname Device3
[Device3] clock ethernet-synchronization enable
[Device3] interface XGigabitEthernet 0/0/1
[Device3-XGigabitEthernet0/0/1] clock synchronization enable
[Device3-XGigabitEthernet0/0/1] quit
[Device3] interface XGigabitEthernet 0/0/2
[Device3-XGigabitEthernet0/0/2] clock synchronization enable
[Device3-XGigabitEthernet0/0/2] clock priority 3
[Device3-XGigabitEthernet0/0/2] quit
[Device3] interface XGigabitEthernet 0/0/3
[Device3-XGigabitEthernet0/0/3] clock synchronization enable
[Device3-XGigabitEthernet0/0/3] clock ssm ssub
[Device3-XGigabitEthernet0/0/3] clock priority 1
[Device3-XGigabitEthernet0/0/3] quit

Configure automatic clock source selection and enable the use of SSM quality level to participate in clock source selection.

# Configure Device1. The configurations of other devices are similar to the configuration of Device1, and are not mentioned here.

[Device1] clock clear slot 0         //If a clock source has been manually or forcibly specified, running this command will restore automatic clock source selection. Otherwise, this step is not required.
[Device1] clock ssm-control on
[Device1] clock run-mode normal slot 0

Verify the configuration.

Run the display clock source command on Device1, Device2, Device3, and Device4 to check the clock sources traced by each device and the status of these clock sources.

# Check result on Device1

[Device1] display clock source
  System trace source State:   lock mode                                        
                               into pull-in range                               
  Current system trace source: XGE0/0/3                                         
  Frequency lock success:      yes                                      
                                                                                
  Slot 0                                                                        
  Source        Pri(sys) In-SSM   Out-SSM     State        Ref Source           
  XGE0/0/1       2         dnu      sec       initial        Yes                
  XGE0/0/2       ---       dnu      sec       initial        No                 
  XGE0/0/3       1         ssua     sec       initial        Yes

# Check result on Device2

[Device2] display clock source
  System trace source State:   lock mode            
                               into pull-in range   
  Current system trace source: XGE0/0/1             
  Frequency lock success:      yes                  
                                                                                
  Slot 0                                                                        
  Source        Pri(sys)   In-SSM   Out-SSM   State          Ref Source
  ------------------------------------------------------------------------------
  XGE0/0/1       1          ssua     dnu       normal         Yes
  XGE0/0/2       2          dnu      ssua      normal         Yes

# Check result on Device3

[Device3] display clock source
  System trace source State:   lock mode            
                               into pull-in range   
  Current system trace source: XGE0/0/2            
  Frequency lock success:      yes                  
                                                                                
  Slot 0                                                                        
  Source        Pri(sys)   In-SSM   Out-SSM   State          Ref Source
  ------------------------------------------------------------------------------
  XGE0/0/1       ---        dnu      ssua      normal         No 
  XGE0/0/2       3          ssua     dnu       normal         Yes
  XGE0/0/3       1          ssub     ssua      normal         Yes

# Check result on Device4

[Device4] display clock source
  System trace source State:   lock mode            
                               into pull-in range   
  Current system trace source: XGE0/0/1             
  Frequency lock success:      yes                  
                                                                                
  Slot 0                                                                        
  Source        Pri(sys)   In-SSM   Out-SSM   State          Ref Source
  ------------------------------------------------------------------------------
  XGE0/0/1       1          ssua     dnu       normal         Yes
  XGE0/0/2       2          dnu      ssua      normal         Yes

Change the SSM quality level of the external clock connected to Device1. Run the display clock source command on Device1, Device2, Device3, and Device4 to check the clock sources traced by each device and the status of these clock sources.

[Device1] interface XGigabitEthernet 0/0/3
[Device1-XGigabitEthernet0/0/3] clock ssm sec

# On Device1, run the display clock source command to check that Device1 traces clock signals transmitted from Device3.

[Device1] display clock source
  System trace source State:   lock mode            
                               into pull-in range   
  Current system trace source: XGE0/0/1             
  Frequency lock success:      yes                  
                                                                                
  Slot 0                                                                        
  Source        Pri(sys)   In-SSM   Out-SSM   State          Ref Source
  ------------------------------------------------------------------------------
  XGE0/0/1       2          ssub     dnu       normal         Yes
  XGE0/0/3       1          sec      --        normal         Yes

# On Device2, run the display clock source command to check that Device2 traces clock signals transmitted from Device3.

[Device2] display clock source
  System trace source State:   lock mode            
                               into pull-in range   
  Current system trace source: XGE0/0/2             
  Frequency lock success:      yes                  
                                                                                
  Slot 0                                                                        
  Source        Pri(sys)   In-SSM   Out-SSM   State          Ref Source
  ------------------------------------------------------------------------------
  XGE0/0/1       1          dnu      ssub      normal         Yes
  XGE0/0/2       2          ssub     dnu       normal         Yes

# On Device3, run the display clock source command to check that Device3 traces clock signals transmitted from the external BITS source.

[Device3] display clock source
  System trace source State:   lock mode            
                               into pull-in range   
  Current system trace source: XGE0/0/3             
  Frequency lock success:      yes                  
                                                                                
  Slot 0                                                                        
  Source        Pri(sys)   In-SSM   Out-SSM   State          Ref Source
  ------------------------------------------------------------------------------
  XGE0/0/1       ---        dnu      ssub      normal         No 
  XGE0/0/2       3          dnu      ssub      normal         Yes
  XGE0/0/3       1          ssub     dnu       normal         Yes

# On Device4, run the display clock source command to check that Device4 traces clock signals transmitted from Device3.

[Device4] display clock source
  System trace source State:   lock mode            
                               into pull-in range   
  Current system trace source: XGE0/0/1             
  Frequency lock success:      yes                  
                                                                                
  Slot 0                                                                        
  Source        Pri(sys)   In-SSM   Out-SSM   State          Ref Source
  ------------------------------------------------------------------------------
  XGE0/0/1       1          ssub     dnu       normal         Yes
  XGE0/0/2       2          dnu      ssub      normal         Yes

Configuration Files

Device1 configuration file

#
sysname Device1
#
clock ethernet-synchronization enable
#
interface XGigabitEthernet0/0/1
 clock priority 2
 clock synchronization enable
#
interface XGigabitEthernet0/0/2
 clock synchronization enable
#
interface XGigabitEthernet0/0/3
 clock ssm ssua 
 clock priority 1
 clock synchronization enable
#
return

Device2 configuration file

#
sysname Device2
#
clock ethernet-synchronization enable
#
interface XGigabitEthernet0/0/1
 clock priority 1
 clock synchronization enable
#
interface XGigabitEthernet0/0/2
 clock priority 2
 clock synchronization enable
#
return

Device3 configuration file

#
sysname Device3
#
clock ethernet-synchronization enable
#
interface XGigabitEthernet0/0/1
 clock synchronization enable
#
interface XGigabitEthernet0/0/2
 clock priority 3
 clock synchronization enable
#
interface XGigabitEthernet0/0/3
 clock ssm ssub 
 clock priority 1
 clock synchronization enable
#
return

Device4 configuration file

#
sysname Device4
#
clock ethernet-synchronization enable
#
interface XGigabitEthernet0/0/1
 clock priority 1
 clock synchronization enable
#
interface XGigabitEthernet0/0/2
 clock priority 2
 clock synchronization enable
#
return