Configuration Examples; Example For Selecting The Clock Source Based On The Priority - Huawei Quidway S9300 Configuration Manual

Quidway S9300 Terabit Routing Switch
Configuration Guide - Device Management
Step 9 Run the display clock { left-frame | right-frame } command to view the priorities of the clock
signals that different interfaces send from the left side or right side of the frame.
Step 10 Run the display clock lockout command to view the locked clock sources.
Step 11 Run the display clock priority command to view the priorities of clock sources.
Step 12 Run the display clock ql-unknown command to view the SSM quality level mapping the
unknown level.
Step 13 Run the display clock selection command to view the clock source selected by each external
clock.
Step 14 Run the display clock ssm-config command to view the SSM quality levels of clock sources.
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11.8 Configuration Examples

This section provides several configuration examples of Ethernet clock syntonization.

11.8.1 Example for Selecting the Clock Source Based on the Priority

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 priorities. In
addition, timing loops must be prevented. A timing loop occurs when the device where the
primary reference clock is located receives clock signals from a clock source with higher priority
and the clock source of the primary reference clock is re-selected.
As shown in
primary reference clock. In this example, the primary reference clock on the ring network is
generated by the local oscillator. In the actual networking, the primary reference clock may be
obtained from the BITS interface of Switch A. The Switches obtain clock signals from the LPUs
and select clock sources based on priorities. Normally, the clock syntonization 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 syntonization direction, as shown by the blue arrows. Switch A is
always the reference clock source.
Issue 03 (2011-12-29)
Figure 11-1, three Switches form a ring network. The clock of Switch A is the
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11 Ethernet Clock Syntonization Configuration
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