Clock Subnet

In this interface, you can query, set or activate clock subnets, clock source IDs, the SSM protocol and the S1 byte of an NE.

Navigation Path

In the NE Explorer, select Configuration > Clock > Physical Layer Clock > Clock Subnet Configuration. Click Clock Subnet tab.
In the NE Explorer, select Configuration > Clock > Physical Layer Clock > Physical Clock Subnet Configuration. Click Clock Subnet tab.
In the NE Explorer, select an board and then select Clock > Physical Clock > Clock Subnet Configuration. Click Clock Subnet tab.

NOTE:

You must divide NEs that have SSM clock protection to clock protection subnets. If you do not divide the NEs to clock protection subnets, SSM is not enabled for the NEs that are not divided to the subnets. This results in incorrect traced clock switching.

Parameters

Field	Value	Description
Affiliated Subnet	0 to 255 Default: 0	Sets the clock subnet number of the NE.
Protection Status	Start Extended SSM Protocol, Start Standard SSM Protocol, Stop SSM Protocol	The same SSM protection protocol must be used within the same clock protection subnet. The standard SSM is a mechanism used for the synchronization management in an SDH network. It is loaded in the lower four bits of the S1 byte in SDH overheads. By allowing for the exchange of the quality information of clock source among nodes, SSM ensures that the equipment automatically chooses the clock source of the highest quality and priority to prevent clock mutual tracing. The SSM protocol can be used in the interconnection with other vendors' equipment. The extended SSM brings forward the concept of clock source ID based on the standard SSM. It uses the higher four bits of the S1 byte to define a unique ID for the clock trace, and is transmitted with the standard SSM together. When a node receives the S1 byte, it checks whether the clock source ID defined in the higher four bits originates from this station. If so, the clock source is unavailable. This scheme prevents the clock from mutual tracing when the clock tracing trail is configured as a ring. The extended SSM protocol is primarily used in the interconnection between Huawei equipment.
Clock Source	For example: Internal Clock Source	Displays the configured clock source of the NE. You can set whether to add or delete a clock source in the clock source priority list.
Clock Source ID	(None), 1 to 15 Default: (None)	Only the four low bits of the S1 byte are defined by ITU-T. Huawei defines the four high bits as the clock ID to identify various clock sources for fear that the NE traces a clock sent out by itself when the network fails, which is called mutual clock trace.