Ceragon FibeAir IP-20 All-Outdoor Series, User Manual

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User Guide for FibeAir® IP-20 All-Outdoor Products, CeraOS 10.5
Page 364 of 825
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9.2.3 Editing a Sync Source
To edit a synchronization source:
1 In the Sync Source page (
Figure 279 ), click Edit . The Sync Source – Edit page
opens.
2 Edit the parameters, as defined above. You can edit all the parameters except
Sync Interface , which is read-only.
3 Click Apply , then Close .
9.2.4 Deleting a Sync Source
To delete a synchronization source:
1 Select the synchronization source in the Sync Source page (
Figure 279 ).
2 Click Delete . The synchronization source is deleted.
9.3 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, IP-20
implements the passing of SSM messages over the radio interfaces. SSM timing in
IP-20 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:
◦
If quality is configured as fixed, then the quality status becomes “failure”
upon interface failure (such as LOS, LOC, LOF).
◦
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.