Example for Selecting the Clock Source Based on the SSM Quality Level
Networking Requirements
On a ring network, the clock of a switch is configured as the primary reference clock. You can set the priorities of clock sources so that the clock source is selected based on the SSM quality level. Timing loops must be prevented.
As shown in Figure 7-8, three switches form a ring network. The clock of SwitchA is the primary reference clock. The switches obtain clock signals from the LPUs and select the clock source based on the SSM quality level. The normal clock synchronization direction is shown by the red arrows. If the clock signal fails to be transmitted in this direction, the switches can quickly change the clock synchronization direction, as shown by the blue arrows.
Configuration Roadmap
- Configure the routing protocol to make the IP routes between the nodes reachable.
- Configure the BITS0 interface of SwitchA to use the BITS clock as the input primary reference clock. (The SSM quality level of the BITS0 clock is PRC.)
- Set the mode of clock source selection on SwitchA, SwitchB and SwitchC.
Procedure
- Verify that the clock of SwitchA is the primary reference
clock and enable the SSM quality level to be used in clock source
selection.
# On SwitchA, enable the SSM quality level to be used in clock source selection and set the priority of the BITS0 clock to 1.
<HUAWEI> system-view [HUAWEI] sysname SwitchA [SwitchA] clock ql-enable [SwitchA] clock priority 1 source 1 system
# View the clock information on SwitchA, and you can see that the inner clock and system clock provide clock signals normally.
[SwitchA] display clock source Reference Clock Source Signal Fail S1 Byte ID SSM --------------------------------------------------------------------- 0 Inner Clock No -- - SEC 1 BITS0 No -- - PRC 2 BITS1 Yes -- - DNU 3 Slave Board BITS0 Yes -- - DNU 4 Slave Board BITS1 Yes -- - DNU 5 Left Frame Clock Yes -- - DNU 6 Right Frame Clock Yes -- - DNU 7 System Clock No -- - PRC
# Verify that the SSM quality level is used in clock source selection.
[SwitchA] display clock mode QL-Enable : Yes. Freq-Check : No. Retrieve : Yes. Hold Type : Hold 24 hours. Run Mode : Free. Bits0 : Locked. Bits1 : Locked. System mode: Auto select clock source 1: BITS0. Bits0 mode : Auto select clock source 9: System Clock. Bits1 mode : Auto select clock source 9: System Clock. Clock time : Free-run
# Verify that the system clock selects the BITS0 clock as the clock source and that the system clock sends clock signal to the LPUs as the output clock signal.
[SwitchA] display clock selection Type Clock Source Selected --------------------------------------------------------------------- system 1. BITS0 bits0 9. System Clock bits1 9. System Clock
- Set the mode of clock source selection on SwitchB.
# On SwitchB, set the priority of the clock signal that GigabitEthernet5/0/7 sends from the right side of the frame to 10, and set priority of the clock signal that GigabitEthernet5/0/3 sends from the right side of the frame to 20. Retain the default WTR time. Set the priority of the clock signal sent from the right side of the frame to 6.
If you want to see the clock source switching result during debugging, set the WTR time to 0.
<HUAWEI> system-view [HUAWEI] sysname SwitchB [SwitchB] clock ql-enable [SwitchB] interface gigabitethernet 5/0/7 [SwitchB-GigabitEthernet5/0/7] clock right-frame 10 [SwitchB-GigabitEthernet5/0/7] quit [SwitchB] interface gigabitethernet 5/0/3 [SwitchB-GigabitEthernet5/0/3] clock right-frame 20 [SwitchB-GigabitEthernet5/0/3] quit [SwitchB] clock priority 6 source 6 system
# View information about the clock sources sent from the right side of the frame. You can see that the clock source of GigabitEthernet5/0/7 is sent to the clock board, and the clock synchronization direction is shown by the red arrows in Figure 7-8.[SwitchB] display clock right-frame Interface Priority Clock Signal Selected --------------------------------------------------------------------- GigabitEthernet5/0/3 20 N GigabitEthernet5/0/7 10 Y
# View the clock information on SwitchB, and you can see that the inner clock, Right Frame Clock, and system clock provide clock signals normally.
[SwitchB] display clock source Reference Clock Source Signal Fail S1 Byte ID SSM --------------------------------------------------------------------- 0 Inner Clock No -- - SEC 1 BITS0 Yes -- - DNU 2 BITS1 Yes -- - DNU 3 Slave Board BITS0 Yes -- - DNU 4 Slave Board BITS1 Yes -- - DNU 5 Left Frame Clock Yes -- - DNU 6 Right Frame Clock No 02 - PRC 7 System Clock No -- - PRC
# Verify that the SSM quality level is used in clock source selection.
[SwitchB] display clock mode QL-Enable : Yes. Freq-Check : No. Retrieve : Yes. Hold Type : Hold 24 hours. Run Mode : Trace.(SyncOK, Locked) Bits0 : Locked. Bits1 : Locked. System mode: Auto select clock source 6: Right Frame Clock. Bits0 mode : Auto select clock source 9: System Clock. Bits1 mode : Auto select clock source 9: System Clock. Clock time : Free-run
# Ensure that the system clock selects the clock source sent from the right side of the frame as the clock source and that the system clock sends clock signal to the LPUs as the output clock signal.
[SwitchB] display clock selection Type Clock Source Selected --------------------------------------------------------------------- system 6. Right Frame Clock bits0 9. System Clock bits1 9. System Clock
- Set the mode of clock source selection on SwitchC.
# On SwitchC, set the priority of the clock signal that GigabitEthernet2/0/3 sends from the left side of the frame to 30, and set priority of the clock signal that GigabitEthernet2/0/0 sends from the left side of the frame to 40. Retain the default WTR time. Set the priority of the clock signal sent from the left side of the frame to 5.
If you want to see the clock source switching result during debugging, set the WTR time to 0.
<HUAWEI> system-view [HUAWEI] sysname SwitchC [SwitchC] clock ql-enable [SwitchC] interface gigabitethernet 2/0/3 [SwitchC-GigabitEthernet2/0/3] clock left-frame 30 [SwitchC-GigabitEthernet2/0/3] quit [SwitchC] interface gigabitethernet 2/0/0 [SwitchC-GigabitEthernet2/0/0] clock left-frame 40 [SwitchC-GigabitEthernet2/0/0] quit [SwitchC] clock priority 5 source 5 system
# View information about the clock sources sent from the left side of the frame. You can see that the clock source of GigabitEthernet 2/0/3 is sent to the clock board, and the clock synchronization direction is shown by the red arrows in Figure 7-8.[SwitchC] display clock left-frame Interface Priority Clock Signal Selected --------------------------------------------------------------------- GigabitEthernet2/0/0 40 N GigabitEthernet2/0/3 30 Y
# View the clock information on SwitchC, and you can see that the inner clock, Left Frame Clock, and system clock provide clock signals normally.
[SwitchC] display clock source Reference Clock Source Signal Fail S1 Byte ID SSM --------------------------------------------------------------------- 0 Inner Clock No -- - SEC 1 BITS0 Yes -- - DNU 2 BITS1 Yes -- - DNU 3 Slave Board BITS0 Yes -- - DNU 4 Slave Board BITS1 Yes -- - DNU 5 Left Frame Clock No 02 - PRC 6 Right Frame Clock Yes -- - DNU 7 System Clock No -- - PRC
# Verify that the SSM quality level is used in clock source selection.
[SwitchC] display clock mode QL-Enable : Yes. Freq-Check : No. Retrieve : Yes. Hold Type : Hold 24 hours. Run Mode : Trace.(SyncOK, Locked) Bits0 : Locked. Bits1 : Locked. System mode: Auto select clock source 5: Left Frame Clock. Bits0 mode : Auto select clock source 9: System Clock. Bits1 mode : Auto select clock source 9: System Clock. Clock time : Free-run
# Ensure that the system clock selects the clock source sent from the left side of the frame as the clock source and that the system clock sends clock signal to the LPUs as the output clock signal.
[SwitchC] display clock selection Type Clock Source Selected --------------------------------------------------------------------- system 5. Left Frame Clock bits0 9. System Clock bits1 9. System Clock
- Verify the configuration.
The commands used to verify the configuration result are included in the preceding steps.
Configuration Files
SwitchA configuration file
# sysname SwitchA # clock ql-enable clock priority 1 source 1 system #
SwitchB configuration file
# sysname SwitchB # clock ql-enable clock priority 6 source 6 system # interface GigabitEthernet5/0/3 clock right-frame 20 # interface GigabitEthernet5/0/7 clock right-frame 10 #
SwitchC configuration file
# sysname SwitchC # clock ql-enable clock priority 5 source 5 system # interface GigabitEthernet2/0/0 clock left-frame 40 # interface GigabitEthernet2/0/3 clock left-frame 30 #