Cambium Networks PTP 820 Series User Manual page 589

Chapter 10: Synchronization
Configuring the Outgoing Clock and SSM Messages
In the Outgoing Clock page, you can view and configure the following synchronization settings per interface:
•
The interface's clock source (outgoing clock).
•
For radio interfaces, the synchronization radio channel (used for interoperability).
•
SSM message administration.
In order to provide topological resiliency for synchronization transfer, PTP 820G and PTP 820F implements the
passing of SSM messages over the radio interfaces. SSM timing in PTP 820G and PTP 820F complies with ITU-T
G.781.
In addition, the SSM mechanism provides reference source resiliency, since a network may have more than one
source clock. The following are the principles of operation:
•
At all times, each source interface has a "quality status" which is determined as follows:
o
If quality is configured as fixed, then the quality status becomes "failure" upon interface failure (such as
LOS, LOC, LOF).
o
If quality is automatic, then the quality is determined by the received SSMs. If no valid SSM messages are
received or in case of interface failure (such as LOS, LOC, LOF), the quality becomes "failure.
•
Each unit holds a parameter which indicates the quality of its reference clock. This is the quality of the current
synchronization source interface.
•
The reference source quality is transmitted through SSM messages to all relevant radio interfaces.
•
In order to prevent loops, an SSM with quality "Do Not Use" is sent from the active source interface (both
radio and Ethernet)
In order for an interface to transmit SSM messages, SSM must be enabled on the interface. By default, SSM is
disabled on all interfaces.
When configuring the outgoing clock and SSM administration, the Sync mode must be set to its default setting of
automatic. To display the current Sync mode, enter the following CLI command in root view:
root> platform sync mode show
If the Sync mode is set to pipe, you must set it to automatic by entering the following CLI command in root view:
root> platform sync mode set automatic
To configure the outgoing clock on an Ethernet interface, the Media Type of the interface must be RJ45 or SFP, not
Auto-Type. To view and configure the Media Type of an Ethernet interface, see Configuring Ethernet Interfaces.To
view and configure the synchronization parameters of the unit's interfaces:
1 Select Sync > Outgoing Clock. The Outgoing Clock page opens.
Configuring the Outgoing Clock and SSM Messages
phn-3965_006v002
Page 10-6