l
On the traditional telecommunications network, the TDM service carried on the AN is
mainly the voice service. Cumulative inconsistency between the clocks at both ends of the
bearer network over a long time causes frame slip, which reduces the quality of the voice
service. Moreover, the wireless application has more rigorous requirements on the clock
frequency. The frequencies of different base stations must be synchronized within a
specified precision. Otherwise, re-sync occurs during the base station switching. Therefore,
clock synchronization is very important in the TDM voice service.
3.8.1 Configuring the Reference Source of the System Clock
This topic describes how to configure the clock reference sources so that the system clock can
select a reference source when needed.
Context
l
To ensure that the MA5616 and other devices on a network use the unified time, the clock
signals of a certain port must be specified as the reference source of the system clock. The
system clock is also used as the system output clock.
l
The system supports a maximum of ten clock reference sources. The system selects a
reference source according to the priority level of each reference source.
l
The reference sources of the system clock include the adaptive clock, and line clock.
–
The adaptive clock restores a clock from the PHS service at the upper layer as the
reference source of the system clock.
–
The line clocks supported by the system include the GE line clock, GPON line clock, .
That is, the system receives a line clock transferred by the upper-layer device through
the GE/GPONuplink interface, and restores the line clock as the reference source of the
system clock, thus implementing clock synchronization with the upper-layer device.
3.8.1.1 Configuring the Adaptive Clock Reference Source
The In the PHS service, the UA5000 sends a unidirectional E1 clock packet to the MA5616.
The MA5616 can use the clock in the packet as the clock reference source.
Procedure
Step 1
Run the
vlan
command to create the VLAN for carrying clock packets.
Step 2
Run the
ip address
command to set the IP address of the Layer 3 VLAN.
Step 3
Run the
port vlan
command to add an uplink port to the VLAN.
Step 4
Run the
acm-clock-ip
command to set the IP address of the Layer 3 interface for receiving
adaptive clock method (ACM) clock packets.
NOTE
The IP address of the Layer 3 interface configured to receive ACM clock packets cannot be used as the IP
address of the NMS interface.
Step 5
Run the
clock source
command to set the ACM clock as the clock source of the system.
----End
SmartAX MA5616 Multi-service Access Module
Configuration Guide
3 Basic Configuration
Issue 04 (2011-10-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
67
