ECS4660-28F_Management Guide-R03

C HAPTER 24 | System Management Commands
Synchronous Ethernet
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synce ssm ethernet This command configures a port to receive/send Synchronization Status
Messages (SSM), and sets the priority used for this port in clock source
port selection. Use the no form to stop using clock selection based on SSM.
SYNTAX
synce ssm ethernet unit/port [priority priority]
no synce ssm [ethernet unit/port]
unit - Unit identifier. (Range: 1)
port - Port number. (Range: 25-28)
priority - The priority used for clock source selection.
(Range: 1-65535)
DEFAULT SETTING
Disabled
COMMAND MODE
Global Configuration
COMMAND USAGE
General Information
◆ SSM provides a mechanism for downstream SyncE devices to
synchronize with the Primary Reference Clock or the highest quality
clock available. If an upstream network failure breaks this link, the
synchronization function can take appropriate action based on SSM and
pre-set priorities to select an alternate source of synchronization.
◆ This command only enables a port to send/receive SSM. It does not
designate a specific port to be used as the clock source port. Use the
synce clk-src-ssm command to configure the clock source.
◆ Only SSM will be extracted from the Ethernet Synchronization Message
Channel (ESMC). No other information from the ESMC will be
forwarded. SSM will be sent out of the specified port indicating the
clock source selected by SSM or the manually configured clock source.
◆ The clock source port will not itself send out SSM. The other SSM-
enabled ports will only send out SSM if received on the clock source
port. SSM will be sent out of the other SSM-enabled ports once a
second. If SSM has not been received on the clock source port after five
seconds, the other SSM-enabled ports will stop sending SSM until a
new clock source is selected.
◆ If SSM is disabled for a port, the priority level will be restored to the
default value.
Mode Changes
◆ The switch can only be configured to use SSM for dynamic clock source
selection when the current selection mode is set to Manual. The mode
cannot be changed directly from SSM mode to Auto mode, or from Auto
mode to SSM mode.