Configuring ACR
This part describes the configuration procedure of ACR.
Usage Scenario
Adaptive Clock Recovery (ACR) are two types of clock synchronization technologies. The clock accuracy of ACR is affected by the Packet Switched Network (PSN). If network clocks are asynchronous, ACR can be used to restore service clocks.According to the clock transparent transmission mode, clock synchronization technologies can be classified into CES and TOP. In CES mode, clock signals are transparently transmitted through TDM from the master clock to the slave clock; in TOP mode, clock signals are transmitted through a PW from the master clock to the slave clock. Currently, Huawei devices support CES-ACR for clock synchronization.
As shown in Figure 8-1, in ACR mode, the downstream slave clock recovers the clock signals from the upstream master clock. In this case, you need to configure a clock recovery domain.
Pre-configuration Tasks
Before configuring ACR, complete the following tasks:
When configuring ACR, ensure that the master and slave devices are equipped with the subcard supporting CES ACR.
Configuring link layer protocol parameters and IP addresses for interfaces to ensure that the link layer protocol on each interface is Up
Configuring static routes or an IGP to ensure reachable routes between nodes
Ensuring that the E1 card is installed in the device before configuring ACR
Procedure
- Run system-view
The system view is displayed.
- Configure a clock recovery domain on the slave device that
needs to restore clock signals.
# If the device is installed with the CPOS card, perform the following operations:
- (Optional) Configure the clock signal restored using ACR
as the system clock on the slave device that needs to restore clock
signals.
Checking the Configuration
# If the ACR function on the router works normally, you can run the display acr-dcr command to view the current ACR information.
<HUAWEI> display acr-dcr slot 1 card 1
# View ACR information of clock recovery domain 4 on subcard 1 of slot 1.
<HUAWEI> display acr-dcr slot 1 card 1 recovery-domain 4
Configuring CES ACR as the system clock
This part describes the configuration procedure of CES ACR.
Context
Configure the clock signal restored using ACR as the system clock on the slave device that needs to restore clock signals.
Procedure
- Run clock source cesacr slot slot-id card card-id recovery-domain domain-value ssm ssm-value, clock source cesacr slot slot-id card card-id recovery-domain domain-value clock-id clock-id, clock source cesacr slot slot-id card card-id recovery-domain domain-value priority priority-value
Clock source attributes are configured for the clock recovery domain, and the recovered clock signal is used as the system clock.
The SSM level for a CES ACR clock source is set.
The clock ID for a CES ACR clock source is set.
The priority for a CES ACR clock source is set.
- Run clock source
cesacr slot slot-id card card-number recovery-domain domain-value synchronization enable
The clock source synchronization for the clock recovery domain is enabled.
- (Optional) Run clock { manual | force } source cesacr slot slot-id card card-id recovery-domain domain-value
A clock selection mode is set and the master clock source is specified.
The clock selection mode can be either manual or automatic.
- Run commit
The configuration is committed.
